Microbiology Exam I

Front 1

Microbiology

Back 1

-The branch of biology that deals with microorganisms and their effects on living organisms
-includes bacteriology, mycology, and virology

Front 2

Bacteria

Back 2

-cellular organisms
-Prokaryotic cell structure
-Single celled organisms
-Enormous diversity
--morphology, metabolic properties, lifestyle
-Account for at least half of the biomass on earth
-Occupy almost every possible ecological niche
--high heat, low heat, dessication, other planets
-Ability to occupy niches depends on structures

Front 3

Classification of Organisms

Back 3

-Based on cell type, rRNA, membrane lipid structure, tRNA, and sensitivity to antibiotics
-All organisms evolved from cells that formed over 3 billion years ago
-DNA has been conserved

1. Bacteria
2. Archea
3. Eukarya
--plants, fungi, mammals

Front 4

Prokaryote

Back 4

-no nucleus, nucleoid region
-Cell wall
-Singular, circular chromosome, haploid
-Cytoplasm is rich in ribosomes
-Smaller in size, 0.1-10 microns
-No organelles or specialized structures
-No Actin to stabilize cell structure
-Specialized surface appendages
-Cannot phagocytose or ingest large particles
-No sexual reproduction, divide via binary fission

Front 5

Eukaryote

Back 5

-Has a membrane-bound nucleus with multiple chromosomes, diploid or polyploid
-Mitochondria and other organelles, specialized structures
-No cell wall
-Tend to be larger, 10-100 microns
-Use actin to stabilize cell structure
-No surface appendages for motility

Front 6

Bacterial classification

Back 6

1. Cell morphology and shape
2. Growth characteristics

Front 7

Morphological shapes of bacteria

Back 7

-Rods (bacilli)
-Cocci (spherical)
-Spiral (spirillum, Spirochete)

-Can be individual, or in groups
--chains, clusters, pairs

Front 8

Gram positive bacteria

Back 8

-Single cell wall with large peptidoglycan layer on the exterior
--peptidoglycan layer is VERY thick, 80% of cell wall
-Rods
-Cocci (spheres)

Front 9

Gram negative bacteria

Back 9

-Much more complex cell wall than gram positive
-inner and outer cell membranes with thin peptidoglycan layer in between
-Outer membrane has specialized phospholipid
-Double membranes make treatments ineffective
-peptidoglycan layer is thin, 5-20% of cell wall
-Rods
-Cocci
-Spiral

Front 10

Growth characteristics of bacteria

Back 10

1. O2 requirement
--aerobic, needs O2
--Anaerobic, no O2
--Faculative
2. Spore formation
3. Intracellular/extracellular existence
4. Fastidious/Non-fastidious (specialized environment vs. non specialized)

Front 11

Types of hemolysis

Back 11

1. alpha: incomplete lysis
2. Beta: exotoxin and hemolysin
--completely lyses RBCs
--Staph
3. Gamma: no lysis

Front 12

Viruses

Back 12

-Non-cellular
-Infectious agents
--parasite that gets into cell and replicates
-Contain both protein and nucleic acid
-Can have DNA or RNA as genetic material
-highly variable genome size
-Have capsid to protect DNA
-May have lipid envelope

Front 13

Virus capsid

Back 13

-Internal part of virus particle
-Viral proteins
-Structural
-Protect genetic material of virus
-Icosahedral capsid= DNA
-Helical capsid= RNA

Front 14

Virus envelope

Back 14

-Lipid cell layer can become protective coating for virus

Front 15

RNA virus morphology

Back 15

-Many different shapes
-Thread-like= ebola
-Rod/Bullet shape= rabies
-Corona viruses have large surface proteins

Front 16

Virus replication cycle

Back 16

1. Attachment
2. Uptake/penetration
3. Uncoating
4. Replication of Viral Nucleic Acid and Synthesis of Viral Proteins
5. Assembly and Maturation
6. Release

Front 17

Eclipse period

Back 17

-In viral replication cycle
-Time from the end of penetration to the beginning of release
-What a virus does while it is inside the cell

Front 18

Viral Replication Cycle:
Attachment

Back 18

-First step
-Viron surface proteins bind to specific host cell receptors
--surface proteins are often glycoproteins
-May be a multi-step event
-Determines tropism of the virus

Front 19

Virus Replication Cycle:
Uptake/Penetration

Back 19

-Receptor mediated endocytosis
--viron is endocytosed into low pH endosomes
-Fusion
--virus fuses with the plasma membrane of the cell at neutral pH

Front 20

Virus Replication Cycle:
Uncoating

Back 20

-Viron must be uncoated for viral genes to be expressed
-Can be complete or partial uncoating
--complete= picornaviruses
--incomplete= reoviruses
-Virus disassembles and genetic information is freed into cell

Front 21

Virus Replication Cycle:
Replication

Back 21

-Replication of viral nucleic acid and synthesis of viral proteins
-Virus machinery or host cell machinery copies genetic info

Front 22

Virus replication cycle:
Assembly and maturation

Back 22

-Viral proteins are assembled at the appropriate site within the cell
-Usually self-assemble

Front 23

Virus Replication Cycle:
Release

Back 23

-Newly-made virons are released via budding or exocytosis
--buds from cellular membranes
-Viral DNA is put back out into the environment

Front 24

Basic Virus Structure

Back 24

-DNA/RNA is encased in capsid proteins
--DNA/RNA+ Capsid proteins= nucleocapsid
-Nucleocapsid with a lipid membrane and glycolipids= enveloped virus

Front 25

Helical RNA capsid

Back 25

-RNA is the string
-Proteins are the pearls
-Form a helical structure

Front 26

Infection

Back 26

-A condition in which pathogenic microbes penetrate host defenses
-Microbes enter tissues and multiply

Front 27

Disease

Back 27

-Any deviation from health
-Disruption of a tissue or organ
-Caused by microbes or their products

Front 28

True Pathogens

Back 28

-Capable of causing disease in healthy persons with normal immune defenses
-Viruses, bacteria, protozoa

Front 29

Opportunistic Pathogens

Back 29

-cause disease when the host's defenses are compromised
-thrive in immunocompromised hosts

Front 30

Localized infection

Back 30

-Microbes enter body and remain confined to specific tissue
-Do not spread to entire system

Front 31

Systemic Infection

Back 31

-Infection spreads to several sites and tissues
-Usually via bloodstream
-Usually a more severe infection

Front 32

Mixed infection

Back 32

-Several microbes simultaneously at site of infection

Front 33

Primary infection

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-Initial infection

Front 34

Secondary infection

Back 34

-Another infection caused by a different microbe
-Can be more severe than the primary infection

Front 35

Sequelae

Back 35

-Long-term or permanent damage to tissues or organs

Front 36

Mortality rate

Back 36

-Total number of deaths in a population due to a certain disease

Front 37

Morbidity rate

Back 37

-Number of animals afflicted with a certain disease

Front 38

Endemic

Back 38

-Disease that exhibits a relatively steady frequency over a long period of time
-Usually in a particular geographic locale

Front 39

Sporadic

Back 39

-When occasional cases are reported at irregular intervals

Front 40

Epidemic

Back 40

-When prevalence of a disease is increasing beyond what is expected

Front 41

Pandemic

Back 41

-Epidemic across continents
-Disease is spreading and more prevalent than what was expected across continents

Front 42

Reservoirs of Infection

Back 42

-Primary habitat in the natural world from which a pathogen originates

Front 43

Living Reservoirs

Non-living reservoirs

Back 43

-May or may not have symptoms
-Asymptomatic carriers
-Vectors: live animals or insects that transmit infectious disease

-Non-living reservoirs= soil, water, abiotic medium

Front 44

Vectors

Back 44

-Live animals or insects that transmit infectious disease

Front 45

Observing Bacteria

Back 45

-Staining allows more visual info, but no context

Front 46

Gram Staining bacteria

Back 46

1. Fix sample
2. Add crystal violet, turn sample blue
3. Wash off sample
--turns sample purple
4. Iodine treatment
5. Wash off
6. Decolorization
--gram + stays purple
--gram - turns clear
7. Counter stain, gram - turns pink

Front 47

Streptococcus Equi

Back 47

-Gram positive cocci bacteria
-Occurs in chains
-Causes equine strangles

Front 48

Staphylococcus pseudintermedius

Back 48

-Gram positive cocci bacteria
-Forms in clusters
-Causes canopyoderma

Front 49

Streptococcus pneumoniae

Back 49

-Gram positive bocci bacteria
-forms in pairs, diplococcus

Front 50

Bacteroides fragilis

Back 50

-Gram negative rod bacteria

Front 51

Corynebacterium pseudotuberculosis

Back 51

-Gram positive rod bacteria
-Pleiomorphic rods, clump together on a slide
-Causes caseous lymphatitis in ruminants

Front 52

Clostridium Sordelli

Back 52

-Gram positive rod and endospore bacteria
-Location of endospore on rod is diagnostic for clostridial infections

Front 53

Campylobacter jejuni

Back 53

-Gram negative spiral bacteria
-Gull-wing shaped spiral on a slide
-Causes diarrhea disease
-True pathogen
--presence on a fecal smear is diagnostic

Front 54

Borrelia burgdorferi

Back 54

-Spirochete bacteria
-Causes Lyme

Front 55

Flagella

Back 55

-Used for locomotion
-Highly antigenic, important for immune recognition (PAMP)
-Come in a variety of forms
-Can be polar, bipolar, multiple, or all over cell surface
--monotrichous= single flagellum
--lophotrichous= multiple flagella
--amphitrichous= bipolar, multiple flagella
--Peritrichous= flagella all around surface of bacteria

Front 56

Bacterial Growth

Back 56

-Orderly increase in all components of an organism
-Based more on time of growth, growth curve is based on time
-Growth curve has characteristic bell shape
--lag phase, exponential growth, stationary phase, death and decline
-Populations decline when nutrient depletion and waste build-up occurs
-In real life growth is not necessarily limited by nutrient depletion and waste build up on a predictable time scale

Front 57

Factors affecting bacterial growth

Back 57

1. Temperature
--thermophiles: heat-loving
--psychrophiles: cold loving
2. pH
--pH range between 6 and 9 is ideal, range of 3-4 units
--during rapid growth, pH range may be reduced
--Pathogens usually have a narrow pH range
3. Nutrients
--Essential elements need to be present in required chemical form
--pattern of growth or no growth in certain environments can be diagnostic
4. Oxygen

Front 58

Oxygen and bacterial growth

Back 58

-Obligate aerobes: need O2
-Obligate anaerobes: need no O2
-Facultative organisms: can grow in O2 or low O2
-Aerotolerant anaerobes: prefer no O2, but can grow in areas with small amounts of O2
-Microaerophilic organisms

Front 59

Microbes

Back 59

-Critical for life on earth as we know it
-Contribute to oxygen and other gasses to environment
--via respiration
-All animals are in constant contact with microbes
--mitochondria in cells
--endogenous microbial flora
--more bacteria cells than human cells on body

Front 60

Commonalities between Prokaryotes and Eukaryotes

Back 60

-Contain nucleic acids (DNA/RNA)
-Contain proteins, lipids, and carbohydrates
-Use similar chemistry to metabolize food, build macromolecules, and store energy
-Clear evolutionary relationship between prokaryotes and eukaryotes

Front 61

Bacterial Cytoplasm

Back 61

-Full of metabolic machinery and macromolecules
--30% stuff, 70% water, MUCH more concentrated that eukaryotic cells
-Allows bacterial to survive on many different surfaces
-20,000-100,000 ribosomes
--powerful protein synthesis machines
--20 AA/second, very fast!
-Viscous environment

Front 62

Cell plasma membrane

Back 62

-Defines the inside of the cell vs. outside environment
-Critical structure for life!
-Acts as osmotic and solute barrier
-All cells have cell membrane
-Composed of proteins, lipids, carbohydrates
-Lipids are asymmetrically distributed into inner and outer leaflets
-Integral membrane proteins, glycoproteins, and peripheral proteins are all important
-Protein complexes allow for passage of specific molecules and electron transport in prok
-Lipid composition varies and gives membrane fluidity

Front 63

Bacterial Plasma Membrane

Back 63

-One membrane has many functions
-Takes on role of organelles in eukaryotic cells
-Antibiotics target bacterial cell walls
-Acts as:
--osmotic barrier
--transport of solutes
--Respiration and electron transport
--Lipid synthesis
--Protein secretion
--photosynthesis

Front 64

Cell functions
Prokaryote vs. Eukaryote

Back 64

1. Osmotic Barrier:
--plasma membrane for both
2. Solute transport
--plasma membrane for both
3. Respiration and Electron transport
--Plasma membrane (prok)
--mitochondrial membrane (euk)
4. Lipid synthesis
--plasma membrane (prok)
--smooth ER/golgi (euk)
5. Protein secretion
--Plasma membrane (prok)
--ER/vesicles (euk)
6. Photosynthesis
--various, including PM (prok)
--chloroplast membrane (euk)

Front 65

Passive Transport

Back 65

-Simple Diffusion
-No energy input needed
-Membrane-permeable molecules O2 and CO2
-Facilitated diffusion: transport along chemical gradient
--need protein channels

Front 66

Active transport of molecules across membranes

Back 66

-Requires input of energy
-Uses breakdown of ATP
--coupled to the inport/export of biologically important molecules
-ATP can be used to modify molecules that enter cells
--ex: glucose → glucose6-P

Front 67

Bacterial protection of the cell wall

Back 67

-PM is critical for bacterial life, must protect
-Protects and prevents cell from rupturing due to osmotic changes
--bacterial are more susceptible to osmotic changes
-Architectural solutions
--gram +
--gram -
--acid fast
--crystalline surface layers (S-layers)

Front 68

Gram + vs Gram - bacteria

Back 68

-Defined by selective staining method
--crystal violet
-Gram + cells stain purple
-Gram - cells do not stain, or stain pink
-Have similar cell wall components that are organized in different ways

Front 69

Peptidoglycan

Back 69

-Made of Murein, unique to bacteria
-Provides protection from high internal turgor pressure
-Linked to cell wall by specialized proteins
-Composed to disaccharide sub-units
--N-acetylmuramic acid and N-acetylglucosamine

Front 70

N-acetylmuramic Acid

Back 70

-Component of bacterial peptidoglycan cell wall layer
-Linked to N-acetylglucosamine
-Cross-linked to form a small tetrapeptide

Front 71

Periplasm
Periplasmic Space

Back 71

-In gram negative bacteria
-Contains peptidoglycan layer

Front 72

Lipid A

Back 72

-In outer leaflet of gram - bacteria
--ONLY in gram - bacteria
-Specialized phospholipid
-Potent inflammatory molecule
-Endotoxin, responsible for endotoxic shock
--rapidly recognized by receptors of the innate immune system
--PAMP
-Composed of 2 linked glucose molecules with 4,6,8 acyl chains

Front 73

Pathogen Associated Molecular Pattern
PAMP

Back 73

-Present in bacteria
-Not present in mammalian cells
-Structure is uniquely present in bacteria
--conserved bacterial structural features
--essential for bacterial viability or lifestyle, absent from host
-Recognized by Pattern Recognition Receptors (PRRs)

Front 74

Mycobacterial envelope

Back 74

-Different from gram+ or gram- bacteria
-Contains mycolic acids
--specialized structures
-Contains lipo-arabino-mannnans
-"Acid-fast" bacteria, need special stain

Front 75

Bacterial cell wall and Antibiotics

Back 75

-Unique structure of cell wall allows targeting by antibiotic therapy
-Bacteria can develop resistance to antibiotics
-Antibiotics target bacterial cell wall, interfere with cell wall assembly
--cause cell wall to become unstable
-

Front 76

S-layer

Back 76

-Surface layer
-Crystalline exterior shell
-Found in archaea and some bacteria
-Protects bacteria from environmental insults
-Protects against bacteriophages and phagocytosis
-Resistance to low pH
-barrier against lytic enzymes
-Allows for adhesion to solid surfaces
-provides bacteria with a way to stabilize the plasma membrane

Front 77

Glycocalyxes

Back 77

-Capsules or slime layers
-Polysaccharides secreted by bacteria
-Attached loosely or firmly to the outside of the bacteria
--loose= slime layer
--firm attachment= capsule
-Important for virulencve
--protects bacteria against phagocytosis and immune-mediated defenses from host
-Allow for bacteria to form biofilms

Front 78

Biofilms

Back 78

-Grow in biotic and abiotic surfaces exposed to fluids
-All over in the environment
-Areas of bacterial colonization
-Colonize medical surfaces and medical devices
--have to coat with antibacterial substances to prevent biofilms
-Teeth and contact lenses are common areas of accumulation

Front 79

Biofilm formation

Back 79

-Follows defined steps
-Needs specific structure

1. Fluid environment with bacteria swimming around
2. Bacteria become loosely attached
3. Irreversible attachment: Bacteria become more firmly attached
4. Maturation: biofilm grows as a result of new bacteria adhering and attached bacteria multiplying
5. Release from colony into fluid environment

Front 80

Biofilm Structures

Back 80

-Defined structures
-Can be composed of multiple bacterial species
-100 different bacterial species can colonize a specific surface
-Mushroom-shaped structures with areas for waterflow
--allows nutrient acquisition

Front 81

Biofilm Attachment and Dispersion

Back 81

-Controlled by distinct bacterial surface structures
-Flagella and Pili
-Pili= important for adhesion
-Flagella= motility

Front 82

Flagella Structure

Back 82

-Basically a little molecular machine
-Protein plates insert into the bacterial membrane
-Proteins form a ring inside the plasma membrane
-Hook formed outside the plasma membrane
-Hook-Associated Proteins connect hook to filament
-Filament is composed by many flagellin proteins
-Direction of swimming is determined by direction of rotation of flagellum

Front 83

Flagella Motility

Back 83

-Proton motive force causes rotation of flagella
--electron transport chain allows rotation and movement
--Proton buildup used to do work, flow down concentration gradient and turn flagellar motor
-Directional swimming is determined by the direction of rotation of flagellum
--Counterclockwise= forward
--clockwise= "tumbling"

Front 84

Gram+ flagella

Gram- flagella

Back 84

-Gram+: portion that spans cell wall does not contain additional proteins

-Gram-: double membrane requires additional proteins to span inner and outer membrane

Front 85

Pili

Back 85

-Long polymeric structures found on bacterial surface
-Used for conjugation, attachment, and protein secretion

1. Conjugative Pili: used for bacterial mating, transfer DNA to other bacteria
2. Pili Attachment: used to attach bacteria to surfaces
--important for biofilm formation
3. Pili and protein secretion: secrete via molecular ratchet
--protein units are inserted, pilus extends past plasma membrane, molecule is placed into environment

Front 86

Conjugative Pili

Back 86

-Direct transfer of mobile DNA elements
-Important mechanism for spread of antibiotic resistance
-Bacteria with specialized mobile plasmids can encode Pili and mechanisms for plasmids to be transferred to bacteria without plasmid
-Allows for bacteria to acquire conjugated plasmids with antibiotic resistance mechanisms

Front 87

Agrobacterium tumefaciens

Back 87

-Bacteria that colonizes plants
-Transfer of bacterial DNA to eukaryotic cells
-Causes Crown gall tumors

Front 88

Bacterial Secretion systems

Back 88

-Allow interaction between bacteria and outside environment
-Types I-VI

Front 89

Type III secretion system

Back 89

-Bacterial injection machine
-Present in gram- bacteria ONLY
-allow bacteria to deliver proteins from cytoplasm to exterior environment
-Closely evolutionarily related to flagellar machinery systems
-Inject virulence proteins into infected cells
--from bacterial cell into mammalian cells
-Form pore in host cell plasma membrane
-Used by many pathogens (Salmonella, Shigella, E. coli, Yersinia)

Front 90

Bacterial Spore

Back 90

-Defined developmental stage of metabolic inactivity
-Enables survival in a harsh environment
-Evolutionary strategy for dealing with extreme environmental stress
-Resistant to extreme temp, pH, dehydration, lack of nutrients
-Forms an endospore via sporulation

Front 91

Endospore

Back 91

-Product of sporulation
-Resistant to many environmental stresses
-Can survive for 1,000s of years as spores
-When exposed to right conditions, will germinate and start growing again
-Allows bacteria to "hide out" until ready
-Bacteria have evolved to form endospores

Front 92

Sporulation

Back 92

-Process of forming an endospore

Front 93

Mutualism

Back 93

-State of infection whereby both the host and the microbe benefit

Front 94

Commensalism

Back 94

-State of host-microbe interaction that does not result in host damage

Front 95

Pathogenicity

Back 95

-Capacity of a microbe to cause damage
-Occurs when host's innate and adaptive immune/defense responses are insufficient
-Level of pathogenicity depends on the pathogen AND the host

Front 96

Virulence

Back 96

-Defines the level of pathogenicity
-Quantity thing

Front 97

Microbial Infection

Back 97

-Colonization of a host by a pathogenic microbe

Front 98

Primary Pathogen

Back 98

-Can colonize the host with a normal innate immune response

Front 99

Secondary pathogen

Back 99

-Opportunistic pathogen
-Can only colonize a host with a reduced innate immune response
-Primary pathogen or other factor must reduce immune system first, then secondary pathogen can come in and F-**** up

Front 100

Infectious Disease

Back 100

-Clinical outcome of host damage by a pathogen
-Occurs after a threshold amount of damage has occurred

Front 101

Persistent Infection

Back 101

-Infection without disease symptoms
-Occurs in an immuno-competent host, host is resistant to the pathogen
-Temporal carrier may or may not have symptoms and shedding
-May be due to a poorly accessible loci of infection for host's defenses
-Temporally or spatially contained until reactivation
-Microbes are non-cultivable, dormant

Front 102

Carrier Stage

Back 102

-Continuous, intermittent, or no shedding into the environment

Front 103

latent infections

Back 103

-persistent infections associated with more or less cellular damage in absence of symptoms
-Not a chronic infection
-Flares up when host is immunocompromised

Front 104

Chronic infection

Back 104

-Longer term infection
-Can have symptoms or not

Front 105

Etiology

Back 105

-Cause leads to effect is proven
-Same organism must be present in every clinical case
-organism must be isolated as a pure culture
-Isolated organism must be able to produce the disease
-Same organism must be reisolated from the reproduced disease

Front 106

Saprophyte

Back 106

-Pathogens live in dead organic material
-Necrotic tissue

Front 107

Host barriers against pathogens

Back 107

1. Mechanical:
--epithelial cells joined by tight junctions
--flow of air or fluid
--movement of mucus by cilia
2. Chemical:
--fatty acids
--low pH
--Enzymes
--antibacterial peptides
3. Microbiological:
--normal flora

Front 108

Voyage of a pathogen leading to Sepsis

Back 108

1. Adhesion: contact with the host
-must be productive contact, must adhere
-mediated by ligand-receptor interaction
2. Invasion: uptake by epithelial cells
-bind to receptors that induce uptake
3. Multiplication: colonization
4. Translocation: spreading in sub-epithelial layers
-can multiply here
-can be taken up by macrophages
5. Dissemination to local lymph node
6. Dissemination to reticulo-endothelial organs
-can multiply and go into the blood in much larger amounts
7. Sepsis!

Front 109

Dendritic cells

Back 109

-Take up pathogens
-Express new receptors on cell surface based on pathogen
-Carry pathogen into lymph node
-Try to kill the pathogen by presenting it to the immune system
-Some pathogens use dendritic cells as "trojan horse" to get into lymph node

Front 110

Host Defense Systems

Back 110

1. Innate immunity: infection recognized by non-specific receptors
2. Early induced response: infection leads to recognition by microbial-associated molecular patterns and inflammation
-infectious agent is removed by effector cells
3. Adaptive immune response: Infection leads to transport of antigen to lymphoid organs and recognition by naive B and T cells
-clonal expansion and differentiation causes removal of infectious agents

Front 111

Virulence Factors

Back 111

-Microbial molecules that support pathogen survival, multiplication, and spreading in the host
-Are responsible for disease symptoms

Front 112

Colonization factors

Back 112

-Molecules on the surface of the pathogen
-Bind to receptors and allow uptake
-can be fimbral or non-fimbral adhesins
--bridge the surfaces of the bacterium and epithelial cells

Front 113

Toxins

Back 113

1. Ligands: recognize specific host receptors and activate or repress cellular signaling pathways
-induce signaling in the host cell
2. Pore-forming: increase cell membrane permeability
-leads to cell-lysis
3. Enzymes: can be secreted by the pathogen or injected by the pathogen
-proteases, glycosiidases, lipases, nucleases, kinases, phosphatases

Front 114

Types of Toxins

Back 114

1. Surface-acting Toxins: bind to receptor on the cell surface and signal something in the cell
-signal over-reaction of T-cells, can end in toxic shock (toxemia)\
2. Pore-forming toxins: assemble in groups to make a pore
-some bind to cholesterol
3. A/B toxins: A= active, B= binding
-Induce endosome formation and can go into golgi and ER or right out into the cytoplasm
4. Syringe system: bacteria have type III or IV secretion system
-secrete and translocate
-Direct injection from bacterial cytoplasm to host cytoplasm, molecule never sees "outside world"

Front 115

Exotoxins

Back 115

-Composed of protein
-DNA genetic material in a phage, plasmid, or pathogenicity island
-Originate from environment
-Target host cell surface, cell membrane, or DNA
-Activity is intracellular or on cell membrane and in DNA
-Highly antigenic, very good antigens

Front 116

Endotoxins

Back 116

-Composed of lipipolysaccharides, are heat stable
-DNA is in a chromosome
-Originate in outer membrane via vesicle blebbing
-Target host cell surface and CD14/TLR4 receptors
--activate signaling responses
-Activity is lipid A or cell signal induction
--pyrogenic, will increase host temperature
-Mildly antigenic, "O-antigen" is the antigenic portion of LPS
--sugars are not very good antigens

Front 117

Host-Microbe interactions

Back 117

-encounter between host and microbe is exceptionally important
-Microbe has to travel through many different tissues to get to target tissue

Front 118

Microbe transmission

Back 118

-Microbe can travel to place it can infect
-Environmental conditions will contribute to pathogenicity
-Transmission can be aerosol (most common), fecal-oral, venereal, vectors (ticks, lice, mosquitos), trans-plancental, ovarian

Front 119

Productive Interaction of Microbe

Back 119

-Microbial adhesion to host cell surface molecules
-Microbe ligand has to be corrext
-Host has to have the right receptor for the pathogen
-Certain factors of host contribute to pathogenicity, something dangerous in one animal might be totally benign in another

Front 120

Microbe progression

Back 120

-Colonization of the host surface
--local multiplication
-Environment on the host bust benefit the microbe
-Need correct nutrients or alternative metabolic pathways
-resistance to the new environment
--proteases or competition, predators in new location

Front 121

Invasion of epithelial barriers

Back 121

-Need a productive ligand-receptor interaction
-Must induce uptake or something in the microbe to be able to inject something into the cell and signal the cell to take it up

Front 122

Invasion of sub-epithelial tissue

Back 122

-Leads to inflammatory response in host
-Polar movements to basolateral side of the epithelium
-Microbe must adapt to the new environment
-Must have extracellular resistance to complement and poly-morphonuclear degranulation products of the host
--have to resist attack form the host
-Inhibition of phagocytic uptake

Front 123

Bacteria and Fe

Back 123

-Most bacteria need iron to survive
-have developed mechanisms to "steal" the iron away from the host
--molecules have higher affinity for the iron than human molecules

Front 124

Microbe inhibition of phagocytic uptake

Back 124

-Inhibition of chemotaxis
-Inhibition of opsonization
--capsule and biofilm contribute
-Binding of surface molecules that do not trigger the uptake
-Cytocidal, aggressive mechanisms to prevent phagocytosis

Front 125

Intraphagocytic survival

Back 125

-Microbe is taken up by macrophage and can grow in macrophage environment
-Can stop phagosomal maturation, no decrease in pH in phagosome
--inhibit proton pump
-Inhibit degranulation, no vacuolar fusion
-Divert lysosomal vacuoles to the cytoplasm
-Resist lysosomal products and oxidative burst
-Have resistance to NO and reactive nitrogen molecules
-Escape phagosome or use phagosomal vacuole to get into cytoplasm

Front 126

Local or Directed Dissemination

Back 126

-Some bacteria are not taken up by phagocytic cells
-Produce spreading factors on own cell surface or via secretion
--Activates plasmogenic plasmids
-Can move quickly in interstitial environment
-Have tissue tropism, be able to move along specific tissues
--Ex: rabies moving along nerve cells

Front 127

Dissemination of microbes to and via lymphatic system

Back 127

-Have to have strong anti-phagocytic activity for extracellular survival
--get to lymphatics on own
-Can act as a "trojan horse" and hide within the phagocyte and be transported to lymphatic system
--intraphagocytic hiding and survival

Front 128

Primary Bacteremia

Back 128

-Microbes have entered blood vessels
-Enter via lymphatic system or subepithelial vessels
-Can enter directly via bite or trauma

Front 129

Uptake of microbes by reticuloendothelial cells

Back 129

-Reticuloendothelial cells= liver, spleen
-Leads to secondary bacteremia (septicemia)
-Microbes must resist clearance by reticuloendothelial cells
-Resist specific immune responses

Front 130

Microbe resistance to specific immune responses

Back 130

-Have high microbial multiplication rate
-High tolerance, be a poor antigen or a prion
-Microbial mimicry of host antigens to induce immune problems
-Result in immunosuppression
-Inhibit cytokine or receptor synthesis/activity
-Inhibit antigen presentation by MHC
-Induce a non-protective response, non-productive antibodies
-Release a soluble "decoy" antigen
-Antigenic variation
-Interfere with normal host cell function

Front 131

Microbe damage to tissues

Back 131

-Multiplication can result in competition and apoptosis
-Microbial toxins can be cytotoxic (damaging) or cytotonic (changing normal physiology)

Front 132

extracellular Toxins

Back 132

-Catabolic enzymes
--proteases
--glycosidases
--lipases
--activation of host enzymes
-Pore-forming toxins (hemolysins)
-Mitogens

Front 133

Intracellular Toxins

Back 133

-Can be A (active) or B (binding) toxins
-Site-specific modifying enzymes

Front 134

Cholera Toxin

Back 134

-Prevents dephosphorylation of G-protein coupled receptor
-alpha-G-protein remains active when toxin is present
-Activates adenylate cyclase in the gut\
-Results in diarrhea

Front 135

Botulism Toxin mechanism

Back 135

-Clostridium botulinum
-blocks actin polymerization
-Deaminates or glycosylates the rho protein of GTPases

Front 136

Rho GTPases

Back 136

-Function as "molecular switches"
-Are inactive when bound to GDP
--kept inactive by a guanine nucleotide dissociation inhibitor
-Activated by Guanine-nucleotide-exchange factors (GEFs)
--interact with variety of downstream effector proteins
-Inactivated by hydrolysis of bound GTP by GTPase-activating proteins (GAPs)
-Rho proteins are attached to the membrane by isoprenylated tails

Front 137

Damage mechanisms of cells

Back 137

-Can be an intracellular microbe that activates a "too-strong" immmune reaction
--causes apoptosis, necrosis
--Uncontrolled immune boost
-Synergism
-Cell-associated toxins
-Inflammatory response from the host
-Immunopathological reactions
-Secondary damage due to coagulation

Front 138

Microbe exit from the host

Back 138

-Has to come out to infect another host!
-Can exit via feces or respiratory tract
-Can be secreted via vesicles
-Can be transplacental
-Come microbes stay in host until it dies, are transferred when another organism eats the dead host

Front 139

Genetic recombination

Back 139

-Process by which genetic elements contained in 2 separate genomes are brought together into 1 unit
-2 genomes become 1 unit
-New genotypes can arise without mutations
-Rare event

Front 140

Horizontal gene Transfer

Back 140

-transfer of genes between organisms without one organism being the offspring of the other
-Common in bacteria
-Major factor in accelerating evolution of bacteria
--important for resistance
-Marked by presence of same gene in organisms that are very distantly related to each other
-3 mechanisms: transformation, transudction, and conjugation

Front 141

Hallmark of Horizontal gene transfer

Back 141

-Presence of same gene in organisms that are only very distantly related to each other
-very common occurrence

Front 142

Transformation

Back 142

-Genetic alteration of a cell resulting from introduction, uptake, and expression of foreign genetic material
-Insertion of DNA directly into a competent recipient cell
-Uptake of DNA from the environment
-Common form of horizontal transfer in bacteria, not so common in eukaryotes
-Only competent strains of bacteria are transformable

Front 143

Vertical gene transfer

Back 143

-Organism receives genetic material from an ancestor
-Parent or species it has evolved from

Front 144

Griffith's 1928 experiment

Back 144

-Injected a mouse with heat-killed S cells and variable R cells
-Caused fatal infection from dead S cells
-Something "transformed" R cells into S cells
-Transformed live organisms into virulent strains by injecting dead organisms
--live organisms were able to take in dead organism DNA
-Basis of molecular genetics

Front 145

Transduction

Back 145

-Process by which bacterial DNA is moved from one bacterium to another by bacteriophage
-Bacteriophage-mediated transfer of bacterial DNA to another bacteria
-Phage coat protects DNA in environment against nucleases
-Usually between members of the same bacterial species, can also occur between species

Front 146

Generalized Transduction

Back 146

-Bacteriophage picks up a piece of DNA from one cell and sticks it in another
-Any genetic marker can be transferred from donor to recipient
-Host DNA is broken down by lytic phage, pieces can be incorporated into replicating phage genome
--breakdown occurs during eclipse period of lytic phase
-Lysate is a mixture of normal and transducing phage
-Transducing phage can infect a new host, recombination can occur
-Usually only pieces of gene is transferred, not full gene
-Rare genetic event, completely random

Front 147

Generalized transduction steps

Back 147

1. Bacteriophage injects DNA into bacterial host cell
2. Phage enzymes degrade host DNA via restriction endonucleases
3. Cell synthesizes new phages that incorporate phage DNA and some host DNA, DNA is packaged into new phages
4. Transducing phages inject new DNA into new host cell
5. DNA is incorporated into host chromosome via recombination
--site-specific recombination at insertion sequences

Front 148

Specialized transduction

Back 148

-Phage transfers a specific set of host genes
-Occurs with temperate phage, virus that does not cause lysis but is integrated
-Only occurs in certain temperate phages
-Specific host genes are integrated directly into virus genome
--transferred during lysogenization
-Bacterial DNA near site of virus inclusion can be transferred only
-If transferred genes are beneficial, host will out-compete other bacteria

Front 149

Temperate phage

Back 149

-A virus that infects host cell but does not necessarily cause lysis
-Can become integrated into host genetic material
-Lysogenization

Front 150

Transduction Summary

Back 150

-Occurs when newly forming phages acquire host genes and transfer them to bacterial cells
-Generalized transduction can transfer any host gene
--occurs with accidental incorporation of host DNA into phage
-Specialized transduction is due to faulty separation of prophage from bacterial chromosome
--New phage includes phage and bacterial genes
--only transfers specific host genes

Front 151

Conjugation

Back 151

-Bacterial mating
-Phenotype marker move from one organism to another
-Involves DNA transfer by actual cell-cell contact
-genetic material transferred may be plasmid or portion of chromosomes mobilized by a plasmid
-Donor transmits genetic information to recipient
-Can occur across species

Front 152

F-plasmid

Back 152

-Episome, can integrate itself into bacterial chromosome via homologous recombination
-100kb plasmid
-Promotes own transfer and replication
-Carries own origin of replication and origin of transfer
-Only one copy exists in each bacterium
-F+ have plasmid, act as donor cells
-F- do not have plasmid, act as recipient cells

Front 153

F-plasmid pilin gene

Back 153

-tra and trb locus
-forms a pili on surface of cell
-Also includes genes for proteins that attach to surface of F- cell and initiate conjugation

Front 154

Conjugation steps

Back 154

1. Donor cell attaches to recipient cell with pilus
-Pilus draws cells together
2. Cells contact each other
3. One strand of the plasmid DNA transfers to the recipient
4. Recipient synthesizes complementary strand fo DNA
-becomes F+ cell
-Donor synthesizes complementary strand to restore its complete plasmid

Ultimately get a population of F+ cells

Front 155

Hfr plasmid

Back 155

-F+ plasmid is inserted directly into host chromosome
-Process is responsible for pathogenicity islands

Front 156

Potential DNA dissemination

Back 156

-lots of "junk" DNA out in the world
-Recipient can acquire any combination of DNA
-Potential for subsequent dissemination fo plasmids and transposons to other recipients is huge
-MAJOR potential for transfer
-Clinically important for multi-drug resistance

Front 157

Importance of Horizontal Gene Transfer

Back 157

-HUGE deal in antimicrobial resistance
-allows for many many connections between different species
-Events don't just occur with bacteria, occur all of the time
-ESSENTIAL for EVOLUTION

Front 158

Evolutionary selection

Back 158

-Selective agents kill exposed or vulnerable populations
-Non-resistant populations die
-Resistant populations survive and proliferate

Front 159

Emergence of Resistance

Back 159

-Organisms with an advantage in environments with severe pressure
-Will thrive where other susceptible organisms will die

Front 160

Bacterial evolution

Back 160

-Ability of bacteria to adapt to new environments
-Results from acquisition of new genes
--via horizontal transfer
-NOT alteration of gene functions via point mutations

Front 161

Plasmids

Back 161

-Molecule of DNA that can replicate autonomously
-Commonly dispensable to the cell
-Distinct from chromosomal DNA
-Found in many types of prokaryotic cells
-Occur in gram+ and gram- cells
-1.5 kb-300kb+, can be big or small pieces of DNA
-Most bacterial plasmids are covalently closed circular DNA molecules
--supercoiled

Front 162

Plasmid Functions

Back 162

-Encode products or functions that modify the phenotype of the cell
-Antibiotic resistance
-heavy metal resistance
-Synthesis of bacteriocins (bacterial toxins)
-Contains restriction endonucleases
-Toxins
-Virulence factors not essential to cellular metabolism

Front 163

Plasmid Transfer Studies

Back 163

-in 1940's and 1950's, studies of recombination in E.coli
-Found unidirectional transfer of genetic information between cells
-Attributed transfer to a transmissible factor F (Fertility Factor)
-F+ cells are donors
-F- cells are recipients
-1961: F factor found to be DNA

Front 164

Conjugation

Back 164

-Transfer of genetic material between bacterial cells by direct cell-to-cell contact or by bridge-like connection between cells
-Method for horizontal gene transfer
-Donor cell provides plasmid or transposon genetic material
-Conjugative plasmids contain transfer genes in an operon
-Some plasmids can also mobilize host cell chromosome for intercellular transfer of info
-Dynamic evolutionary process

Front 165

Bacteriophage

Back 165

-AKA "Phage"
-Any virus that has a bacterial host
-Most/all bacteria can be infected by a phage
-Any given phage can infect one or a few strains or species of bacteria
--specific phages interact with specific bacteria species
--Helpful for experimentation and research
-Majority of nucleic acid composition on the planet is in bacteriophages
-Highly diverse group
-Morphologically can be small and simple or complex

Front 166

Bacteriophage morphology

Back 166

-Filamentous
-Icosahedral
-Head and tail: tail is contractile and fibers recognize certain proteins on cell surface

Front 167

Phage genome

Back 167

-Nucleic acid in phage can be DNA or RNA, not both
-Nucleic acids often contain unusual or modified bases
--protect phage nucleic acid from nucleases
--harder to break down during phage infection, avoids restriction enzymes
-Size of nucleic acid varies by phage
-Codes for protein coat, DNA replication, and integration into the host cell

Front 168

Phage replication

Back 168

-Replication cycle begins when virion adsorbs to host at specific cell surface sites, ATTACHMENT
--sites= components of cell wall, flagellum, sex pilus, etc.

Front 169

Virion

Back 169

-Complete virus particle with DNA or RNA core and protein coat as it exists outside of the cell
-AKA viral particle

Front 170

Phage Infection

Back 170

-Severity of infection depends on phage, host, environmental conditions
--some conditions are not conducive to phage infection
-Virulent phages will induce lytic cycle in host cell
-Temperate phages establish non-lytic relationship (lysogeny)

Front 171

Plaque assay

Back 171

-Assay for lytic phage
-Plaque is clear area that results from lysis of bacteria
-Each plaque arises from a single infectious phage
-Infectious particle that gives rise to plaques = "Plaque forming Unit"
-Can count plaque units, size of plaque is characteristic of the organism

Front 172

Lysogeny

Back 172

-Stable, non-lytic relationship between temperate phage and living host
-Does not produce progeny virions
-Virus integrates into bacterial chromosome and is replicated each time a cell divides
-Lysogenic host cell continues to grow and divide
-Replication of the prophage (phage genome) is coordinate with host replication

Front 173

Prophage

Back 173

-Nucleic acid from virus incorporated into bacterial DNA
-In lysogenic stage, viral DNA just sits there and replicates each time the host cell replicates

Front 174

Transposable Elements

Back 174

-"Jumping Genes"
-Normal components of chromosomes that can translocate to another target site in same replicon or to a target site in another replicon in the same cell
-Found in prokaryotes and eukaryotes
-Can move from one site in the chromosone to another

Front 175

Replicon

Back 175

-DNA or RNA molecule or region of DNA/RNA
-Replicates from a single origin of replication

Front 176

Insertion Element

Back 176

-Allows organism DNA to come into contact with compatible DNA regions in other DNA
-Long strands of similar base sequences that allow matching
-Sit on either site of a specific gene
-Central region encodes 1-2 enzymes for transposition
--flanked by inverted repeats
-5' and 3' ends are short direct repeats generated from target site DNA
--length of repeats is constant for a given IS element, sequence depends on site of insertion
-IR-IS-IR-bacterial gene-IR-IS-IR
-IR-IS-IR= insertion sequence

Front 177

Transposon

Back 177

-Transposable element
-Encodes functions necessary for transposition and also unrelated functions
--antibiotic resistance, heavy metal resistance, restriction endonucleases, toxins, virulence factors
-Critical elements for bacterial gene transfer
-Can jump around a chromosome and cause mutations
-Flanked by copies of same insertion sequence element
-Contain 1 or more protein-coding genes along with genes required for transposition
-Can be introduced to plasmids or viral genomes
-Can act as mutagens

Front 178

Composite transposon

Back 178

-Most common type of transposon
-Contain a sequence containing structural genes flanked on both sides by same insertion sequence
-Transposase snips DNA and allows transposing to occur

Front 179

General Transposon Structure

Back 179

-Insertion sequence---protein coding region---Insertion sequence

Front 180

Gram Positive Cocci

Back 180

-divided into 2 groups based on production of catalase
-Catalase+: Micrococcus, Staphylococcus, Rothia
-Catalase-: Streptococcus, Enterococcus, Eremococcus, Gemella, Globicatella, Helococcus, Vagococcus

Front 181

Catalase

Back 181

-Extracellular enzyme
-Inactivates hydrogen peroxide and free radicals in macrophages
-Leads to intracellular survival of bacteria

Front 182

Staphylococcus

Back 182

-Gram+ bacteria
-Occurs in clusters of pairs and short chains
-30 species of veterinary importance, 3-4 really important

Front 183

Coagulase

Back 183

-Clumping factor that binds to fibrinogen
--get agglutination-type effect in plasma
-Can exist free or cell-bound to prothrombin
-Catalyzes the conversion of fibrinogen to fibrin
--coats bacterial cells with fibrin, makes them more resistant to opsonization and phagocytosis
--Defense mechanism to ensure survival of bacteria in host
-Production of coagulase is a test to determine pathogenicity of staphylococci

Front 184

Staphylococci of Veterinary Significance

Back 184

-Staphylococcus intermedius (dogs, mink, horses, cats, birds)
--Staphylococcus pseudointermedius (dogs)
-Staphylococcus aureus (cows, birds, pets)
-Staphylococcus hyicus (pigs, cows)
-Staphylococcus schleiferi (dogs)
-Staphylococcus delphini (dolphins)
-Staphylococcus felis (cats)
-Staphylococcus lutrae (sea otters)

Front 185

Staphylococus pseudointermedius in cats and dogs

Back 185

-Canine pyoderma
-Osteomyelitis
-Arthritis (in systemic infections)
-Mastitis
-Otitis externa
-Triple Phosphate urolithiasis

Front 186

Staphylococcus schleiferi in dogs and cats

Back 186

-Otitis externa
-Otitis media
-Pyoderma
-Can lead to sever ear disease!

Front 187

Staphylococcus Aureus in Ruminants

Back 187

-mastitis
--acute in sheep and goats
--Chronic in cows
--Leading cause of mastitis
-Tick pyemia of lambs, associated with tick-borne fever
-Abscess disease in sheep

Front 188

Staphylococcus aureus in Horses

Back 188

-Mastitis
-Pectoral abscesses
-Spermatic cord abscesses following castration
-MRSA, transmitted between infected animals and humans

Front 189

Methicillin-resistant Staphylococcus aureus

Back 189

-Common in horses
-Have hostpital-associated MRSA in companion animals
-Animals can have MRSA and give it to humans
--act as reservoir for infection or re-infection
-infects humans and animals
-Is exceptionally hard to treat
-Causes minor SSTIs, can cause serious wound infection post-surgery
-Causes endocarditis, hospital-acquired pneumonia

Front 190

Staphylococcus hyicus in Pigs

Back 190

-Exudative epidermitis
-Affects young pigs, 7 weeks old
-Systemic and rapidly fatal
-Affects lungs, lymph nodes, kidneys, brain
-Skin lesions have thick grey-brown exudate around face and ears
-Exfoliative toxin
-Can move through a herd very quickly
-Is usually treatable

Front 191

Staphylococcus aureus and birds

Back 191

-Bumblefoot
-Chronic pyogranulomatous process in subcutaneous tissues of foot
-Superficial invaders that can spread deeper

Front 192

Pathogenicity

Back 192

-Ability of an organism to cause a pathological process

Front 193

Virulence

Back 193

-Factors that contribute to a pathological process

Front 194

Virulence factors

Back 194

-Adhesins
-MSCRAMMs
-Viral capsule
-Cell wall
-Protein A
-Enterotoxins and Pyrogenic toxin
-Hemolysins

Front 195

Adhesins

Back 195

-Bacterial Surface proteins
-Bind ECM proteins of host
--fibronectin, fibrinogen, collagen, vitronectin, laminin
-Virulence factor

Front 196

MSCRAMMs

Back 196

-Microbial surface components recognizing adhesive matrix molecules
-Can be tissue specific
-Give certain strains affinity to different tissue types
-MSCRAMMs that bind fibrinogen give cell anti-phagocytic properties
--act as host-mimicry and allows organism to avoid phagocytosis

Front 197

Viral capsule

Back 197

-Virulence factor
-S. aureus produces 11 serologically different capsules\
-Genes for capsules are located on Staphylococcal Cassette Chromosome pathogenicity element
-Prevents phagocytosis, allows macrophage avoidance

Front 198

Cell wall of gram+ bacteria

Back 198

-Contains teichoic acids and peptidoglycan
--interact with macrophages to release proinflammatory cytokines
-Promote adherence to mucosal surfaces

Front 199

Protein A of Staphylococcus aureus

Back 199

-Has ability to bind to Fc fragment of immunoglobulins
-Prevents phagocytosis
-interferes with opsonization and ingestion of organism by PMNs (neutrophils)
-Important virulence factor

Front 200

Enterotoxins and Pyrogenic toxin

Back 200

-Superantigens, can stimulate T-cells regardless of antigenic specificity
-Exotoxins include 11 enterotoxins (A-M)
-Cause TSS
-Cause cytokine storm due to interaction with T-lymphocyte cell receptors and macrophages

Front 201

Hemolysins

Back 201

-Toxins that have important role in pathogenesis of Staphylococcal infections
-Act on cell membranes and cause leaky cells
-Alpha, beta, gamma, and delta toxins
--all 4 lyse RBCs, ONLY on blood agar plate (not in real life)
-Hemolysis is NOT observed during disease process

Front 202

Streptococcus

Back 202

-Gram+ cocci, pairs, or chains (chains are very common)
-Facultative anerobes
-55 different species
-Considerable ecologic and genetic diversity

Front 203

Facultative anaerobe

Back 203

-Organism that makes ATP by aerobic respiration of oxygen is present
-Is capable of switching to fermentation if necessary
-Concentration of O2 and fermentable material in the environment influence organism's use of aerobic respiration vs. fermentation

Front 204

Morphology of Streptococcus

Back 204

-Spherical to short rod-shaped cells
-1 micrometer diameter
-Cell division occurs in one plane, produces pairs and chains
-Some species consistently produce chains
-Young cultures are gram+
-Exudates and old cultures are gram variable
-All are catalase negative (opposite of staph)

Front 205

Hemolysis

Back 205

-Breakdown of RBCs
-Ability of bacterial colonies to induce hemolysis on blood agar is used to classify microorganisms
-Useful especially with streptococcal species
-Diagnostic tool only for streptococci

Front 206

Alpha streptococcus hemolysis

Back 206

-Not true hemolysis
-Produces methemoglobin
-Produces green discoloration around colony
-Caused by hydrogen peroxide produced by bacterium, oxidizes hemoglobin to methemoblobin
-Most commensal streptococci

Front 207

Beta hemolysis

Back 207

-Pathogenic
-"complete hemolysis"
-Officially lyses RBCs, complete cleavage of RBCs
-Produces a clear zone of hemolysis, area underneath is clear and transparent
-Most beta-streptococci are pathogenic
--S. pyrogens, S. canis, S. equi, S. zooepidemicus, S. agalactiae

Front 208

Gamma hemolysis

Back 208

-no hemolysis, agar around colony is unchanged
-Most are non-pathogenic organisms or opportunistic
-Enterococcus faecalis

Front 209

Serogrouping

Back 209

-20 serogroups, A - H and K-V
-Animal pathogens are groups A,B,C,D,E,G,L,V
-Identification of streptococci depends on serologic reactivity of "cell wall" polysaccharids antigens
-Some groups are shared by more than one species
-Use anti-serum to test against isolated serum
-S. uberis, S. parauberis, and S. pneumoniae do not have a group, not groupable

Front 210

Pathogenesis factors for Bacteria

Back 210

-Bacteria have major success as pathogens due to ability to colonize, rapidly multiply, and spread in host wile evading phagocytosis
-Rapidly colonize and multiply populations
-Spread in the host
-Evade phagocytosis: coat in proteins that are normally host associated
--avoid immune system

Front 211

Acute diseases accociated with Streptococcus pyogenes

Back 211

-Occur mostly in respiratory tract, bloodstream, or skin
-Most often respiratory infection or skin infection
-Certain strains have preference for specific areas

Front 212

Streptococcus pyogenes

Back 212

-Leading cause of uncomplicated bacterial pharyngitis and tonsillitis (strep throat)
-Can also cause sinusitis, otitis, and pneumonia
-Cell surface is complex and chemically diverse
-Antigenic components on cell surface:
--capsular polysaccharide (C-substance)
--cell wall peptidoglycan and lipoteichoic acid
--Variety of surface proteins (M-protein, fimbral proteins, fibronectin-binding proteins)
--cell-bound streptokinase

Front 213

Streptococcus pyogenes adhesins

Back 213

-Surface proteins that bind to host ECM
-Lipoteichoic acids anchored to proteins on bacterial surface
-M-protein
-fibronectin-binding proteins (Protein F)
--mediates streptococcal adherence to amino terminus of fibronectin on mucosal surface

Front 214

Hyaluronic acid capsule

Back 214

-Produced by Streptococcus pyogenes
-Constituent of human connective tissue
-Poorly immunogenic, does not bind to complement
-Anti-phagocytic
-Capsule acts as an adhesin with affinity for human epithelial cells via CD44 (HA binding glycoprotein)
-Allows organism to effectively evade the immune system

Front 215

Cell wall as a virulence factor

Back 215

-Gram+ cell wall contains lipoteichoic acids and peptidoglycan
--interact with macrophages, results in release of pro-inflammatory cytokines

Front 216

M-protein

Back 216

-Cell wall protein
-Associated with colonization and resistance to phagocytosis
-Imparts anti-phagocytic properties to bacterial cells
-Binds to fibrinogen, blocks binding of complement to peptidoglycan
-Anchored in cell wall membrane, extend through the peptidoglycan layer and projects from the surface of the cell
-Strains rich in M-protein resist phagocytosis and intracellular killing by PMNs
-Allows for host mimicry, inhibits phagocytosis

Front 217

Pneumococcal surface antigen

Back 217

-Lipoprotein found on Streptococcus pneumoniae, Streptococcus equi equi and Streptococcus equi zooepidemicus
-Cause respiratory diseases
-Responsible for binding to cells that line upper and lower airways

Front 218

Pyrogenic Exotoxins

Back 218

-Toxins that act as superantigens
-Do not require processing by antigen-presenting cells
-Stimulate T-cells by binding to class II MHC molecules directly and non-specifically
-20% of T cells can be stimulated
-Results in massive detrimental cytokine release

Front 219

Toxins that may or may not play a role in disease

Back 219

-Might be species dependent?
-Streptolysin O (oxygen labile)
-Streptolysin S (oxygen stable)
-Hyaluronidase
-DNAases
-Proteases
-Streptokinases

Front 220

Transmission of Streptococci

Back 220

-Most are commensuals of upper respiratory, alimentary, and lower genital tracts, or deep penetrating wounds
-Transmitted by:
--inhalation/ingestion
--sexually
--congenitally
--indirectly via hands or fomites
-Can be VERY contagious

Front 221

Group A Streptococci

Back 221

-Streptococcus pyogenes
-Strep throat
-Pyoderma
-Puerperal fever
-Scarlet fever
-Rheumatic fever
-Streptococcal toxic shock syndrome
-Necrotizing fasciitis (flesh-eating disease)

Front 222

Group B Streptococci

Back 222

-Streptococcus agalactiae
-neonatal sepsis, leading cause of neonatal sepsis
-mastitis

Front 223

CAMP test

Back 223

-test to identify group B streptococci
-Organism will form CAMP factor, enlarges area of hemolysis formed by b-hemolysin from staphylococcus aureus
-Used to identify Streptococcus agalactiae
-Presents with a wedge-shape in presence of Staphylococcus aureus

Front 224

Group C Streptococci

Back 224

-Streptococcus dysgalactiae- dysgalactiae (mastitis)
-Streptococcus dysgalactiae- equisimilis (supprative conditions)
-Streptococcus equi- equi (strangles)
-Streptococcus equi- zooepidemicus (pneumonia

Front 225

Group D Streptococci

Back 225

-Enterococcus
-Streptococcus bovis
-Streptococcus equinus

Front 226

Group D Streptococci

Back 226

-Streptococcus canis
-Infects carnivores
-Feline lymphadenitis
-Pyrogenic conditions of dogs, cats, humans
-Secondary pneumonia in dogs and cats
-Septicemia in puppies
-Associated with TSS and necrotizing fasciitis in dogs

Front 227

Group E Streptococcus

Back 227

-Streptococcus porcinus
-Causes lymphadenitis (jowl abscesses)
--contagious in pigs

Front 228

Group R, S, RS, T Streptococccus

Back 228

-Streptococcus suis
-Encephalitis, meningitis, arthritis, septicemia, abortion, endocarditis in pigs
-Occasional cause of septicemia in birds
-Some strains will cross-react with group D antiserum
-Palatine tonsilar carrier state can approach 100%
--piglets can be infected at birth

Front 229

Ungroupable Streptococcus

Back 229

-Streptococcus uberis (bovine mastitis)
-Streptococcus pneumoniae
--pneumonia, septicemia, mastitis, calf septicemia, meningitis
--leading cause of pneumonia in primates
--Type III infection common in horses

NOT susceptible to penicillin

Front 230

Enterococcus

Back 230

-Previously group D Streptococcus
-Genus of lactic acid bacteria
-Gram+ cocci, often occur in pairs or short chains
--difficult to distinguish from Streptococci
-Facultative anaerobic organisms, do not require oxygen for metabolism but can survive in O2 rich environments
-Exhibit gamma hemolysis
-28 species
-Mostly opportunistic pathogens
-Cause enteritis, septicemia, mastitis, respiratory disease, and UTI

Front 231

Enterococcus diagnosis

Back 231

-Colonies are small, gray, smooth, round
-Usually alpha or gamma hemolytic
-80%belong to group D
-All grow in presence of 6.5% NaCL
-Bile esculin positive

Front 232

Vancomycin Resistant Enterococcus faecium
VRE

Back 232

-Important nosocomial pathogen (acquired from hospitals)
-Emerging disease in veterinary medicine
-Found in digestive and urinary tract of some humans
-Enhanced ability to pass resistant genes to other bacteria

Front 233

Bacillus

Back 233

-Gram+ bacteria
-Rod-shaped
-Spore forming
-Obligate aerobes or Facultative anaerobes
-Catalase positive
-Free-living and pathogenic species
-Ex: Bacillus cereus and Bacillus anthracis

Front 234

Bacillus anthracis history

Back 234

-First bacterium shown to be the casue of a disease
-Formed endospores and injected it into animals

Front 235

Koch's postulates

Back 235

-1877
-Used to determine whether a particular micro-organism is the causative agent of a disease
-Useful start, but ended up not being true all the time
-Turns out disease is contextual, depends on host, strain of bacteria, environment, etc.

1. Parasite occurs in every case of the disease in question
--occurs under circumstances which can account for the pathological changes and clinical course of the disease
2. parasite occurs in no other disease as a non-pathogenic parasite
3. After isolation from body, repeated growth in pure culture, parasite an induce the disease again

Front 236

Molecular Kock's Postulates

Back 236

-1988
-Used to determine whether a particular gene is responsible doe a virulence phenotype
1. Phenotype or property under investigation should be associated with apthogenic members of a genus or pathogenic strains of a species
2. Inactivation fo genes associated with the suspected virulence train should lead to a measurable loss of pathogenicity
-specific inactivation or deletion of genes should lead to loss of function in the clone
3. Reversion or allelic replacement of the mutated gene should lead to restoration of pathogenicity
-Restoration of pathogenicity should accompany the reintroduction of the wild-type genes

Front 237

Bacillus anthracis

Back 237

-Gram+ spore-forming bacteria
-Large block-shaped rods
-Central spores develop under all conditions except in the living body
-Polypeptide capsule and exotoxins as virulence factors
--capsule is antiphagocytic
-3 types, depend on route of infection
--cutaneous, pulmonary, gastrointestinal
-Once animal is dead, bacteria turns back into spores

Front 238

3 types of Bacillus anthracis

Back 238

1. Cutaneous: spores enter through skin
-least dangerous, 20% mortality
-Most common, 95% of infections
-have more time to administer antibiotics
2. Pulmonary: inhalation of spores
-Most deadly, 100% mortality
3. GI: ingested spores via contaminated food or water
-high mortality

Front 239

Inhaled Anthrax

Back 239

-particularly deadly
-Lungs are the ideal environment
-Spores are dormant when breathed in, germinate when exposed to warm, moist lung environment
-Small particles spread into alveoli and multiply
--eventually spread to lymphatic system
-Spores germinate in lymph nodes and toxins are released
-Anthrax can live for a LONG time in the environment

Front 240

Anthrax Geography

Back 240

-naturally-occuring areas are tropical, subtropical
--india/pakistan
--Africa, south america
-Regions with alkaline soils (high N) due to decaying vegetation
--Alternating periods of ran and drought
--temperatures more than 15C/60F
-Distribution depends on conditions allowing sporulation in carcass discharges and vegetative multiplication in the soil

Front 241

Anthrax disease in ruminants

Back 241

-Disease is similar in most ruminants
-Septicemia is typical presentation
-Sudden onset of high fever and bleeding from body openings
-Edema

Front 242

Anthrax symptoms in horses

Back 242

-Colic
-Edematous swellings of the throat, beck, and shoulders

Front 243

Bacillus anthracis Cycle

Back 243

1. spores in soil ingested/inhaled
2. Spores germinate and multiply
--release toxins, capsule, S-layer, stress factors
3. Bacilli released into the environment
--sporulate in contact with air

Front 244

Anthrax prevention

Back 244

1. Vaccine: yearly vaccine
2. Dispose of animal carcasses
-disinfect with oil, burn, bury deep, cover with quicklime
3. Spores will not form inside carcass
-putrefaction kills bacillus
-FLIES feeding on blood may be issue
4. Industrial protection
5. Education
6. Reporting of incidences

Front 245

Diagnosis of inhalation anthrax

Back 245

-Sudden onset of respiratory distress
-Mediastinal widening on X-ray
-Small number of patients may also have GI or cutaneous anthrax
-Definitive diagnosis: Gran stain of blood and blood cultures
--may be late findings in course of illness
-ELISA and immunohistology testing

Front 246

Inhalation anthrax treatment

Back 246

-Usually futile, esp. in severe patients
-Ciprofloxacin
-Doxycycline
-Post-exposure oral prophylaxis
-FDA licensed anthrax vaccine

Front 247

Anthrax treatment and prevention in Animals

Back 247

-Penicillin
-Tetrcycline/chloramphenicol
-Erythromycine, Clindamicine
-Vaccine animal herds
-Proper disposal of carcasses
-Active immunization with spores of live attenuated bacilli
--made by colorado serum

Front 248

Virulence factors of Anthrax

Back 248

-Virulence resides in 2 different plasmids
-Complex toxin composed of:
--protective antigen
--edema factor
--lethal factor
-S-layer increases resistance to attack from complement
-Outer capsule is the critical virulence factor (encoded on a plasmid)
-Expression of virulence factors is regulated by host temperature and CO2 concentration

Front 249

Anthrax edema factor

Back 249

-Enzyme that inhibits immune response
-Evades phagocytosis by macrophages
-increases cAMP

Front 250

Anthrax lethal factor

Back 250

-Enzyme that inhibits critical macrophage signaling pathways
-Induces rapid pro-inflammatory cell death

Front 251

Bacillus cereus

Back 251

-related to anthrax
-Does not cause disease in animals but can in humans
-Common airborne and dust borne bacteria
-Large, motile, saprophytic bacteria
-Grows in foods
-Spores survive cooking and reheating
-Ingestion of food containing toxin causes nausea, vomiting, abdominal cramps, diarrhea
--symptoms depend on specific toxins present
-Lasts for 24 hours
-No treatment
-tends to be self-limiting

Front 252

Bacillus cereus Emetic Form

Back 252

-Pre-formed heat and acid stable toxin
-Causes rapid violent vomiting
-Incubation period is less than 6 months
-Lasts 8-10 hours

Front 253

Bacillus cereus diarrheal form

Back 253

-Gastroenteritis
-Heat labile enterotoxin
-Incubation period is more than 6 hours
-Causes diarrhea
-Lasts 20-36 hours

Front 254

Corynebacteria

Back 254

-Corynebacteria diptheriae
-Causes diptheria in humans
-Bacterial toxin causes formation of double membranes in upper respiratory tract
--leads to suffocation
-DPT vaccine largely eliminated diptheria in developed countries
-HIGHLY contagious, 100,000-200,000 cases per year in 1920's
-Iditarod race based on run of vaccine to Nome

Front 255

Corynebacterium in Animals

Back 255

-Mostly opportunistic pathogens
-Corynebacterium bovis
-Corynebacterium renale
-Corynebacterium ulcerans
-Corynebacterium pseudotuberculosis

Front 256

Corynebacterium bovis

Back 256

-Infects cattle
-Causes subclinical mastitis
-Commensal bacterium in bovine udder
-Reduces milk production
-Spread from cow to cow during milking due to poor hygiene

Front 257

Corynebacterium renale

Back 257

-Infects cattle
-Causes cystitis and pyelonephritis in cattle

Front 258

Corynebacterium ulcerans

Back 258

-Infects cattle
-Causes mastitis
-Produces toxin

Front 259

Corynebacterium pseudotuberculosis

Back 259

-Infects sheep and goats
--causes caseous lymphadenitis
--results in enlargement of superficial or internal lymph nodes
-Causes equine lymphangitis
-Causes ulcerative lymphangitis in cattle

Front 260

Corynebacterium pseudotuberculosis
"Pigeon Fever"

Back 260

-In horses
-Abscesses and sores along pectoral muscles of chest
-caseous lymphadenitis
-Internal abscesses in spleen, liver, kidneys, lungs
--mid-line of the belly and groin area also affected
-More common in dry, hot climates in late summer and early fall
-bacterial live in soil
--enter through wounds, broken skin, mucous membranes
-Flies are transmission vectors

Front 261

Caseous Lymphadenitis

Back 261

-Internal abscesses on liver and lungs
-Severe economic impact on sheep and goat industries
--reduction of wool, meat, and milk production
-Results in condemnation of carcasses and skins
-bacterial lesions are resistant to antibiotics
-Vaccines have poor efficacy, are not licensed for all species or in all countries
--require multiple injections

Front 262

Treatment for corynebacterium pseudotuberculosis

Back 262

-Formation of abscesses limits penetration and effectiveness of antibiotics
--abscesses are walled off from body and antibiotics
-Prophylactic and therapeutic treatment does not eliminate corynebacterium pseudotuberculosis from infected flocks/herds
-Abscesses frequently recur regardless of draining or surgical removal
-Cull affected animals and isolate young unaffected animals from older animals

Front 263

Rhodococcus equi

Back 263

-Gram+ aerobic coccobacillus
-Non-motile
-Facultative intracellular bacteria, can grow inside cells and also survive in environment
-Partially acid-fast
-In horses and foals, pigs, cattle, cats

Front 264

Rhodococcus equi transmission

Back 264

-Bacteria has simple nutritional requirements, easily filled by manure
-Organism reaches lung via inhalation
-Dusty manure-contaminated environments are lethal sources of infection
-Can multiply to extremely high numbers in intestine of young foals
-Are shed into environment, 10,000 organisms per gram of manure
-Mostly in young horses, younger thn 12 weeks

Front 265

Disease incidence of Rhodococcus equi

Back 265

-Incidence peaks in foals 6-12 weeks of age
--Maternal antibodies are declining, antibody production in foal is not yet developed
-Accounts for 10% of all foals sent for necropsy
-45% of all foals with pneumonia
-Important in young foals!!

Front 266

Rhodococcus equi treatment

Back 266

-Rifampin and erythromycin
-Long trearment course and high rate of disease recurrence
-Bacteria in granulomas are resistant to antibiotics
--resist killing by macrophages
-Treatment is lengthy, expensive, and has many side-effects
-MASSIVE tissue destruction caused by bacteria

Front 267

Rhodococcus equi virulence mechanisms

Back 267

-Resist macrophage degradation
-Capsule, polysaccharide is anti-phagocytic
- Virulence plasmid in vapA genes
-Causes abscesses and granulomas to form
-Tissue necrosis and damage

Front 268

Rhodococcus equi pathogenesis

Back 268

-Creates abscesses and granulomas
-Pyogranulamatous pneumonia
--insidious disease course
-MASSIVE tissue destruction caused by bacteria
-Immune-mediated synovitis
-Septic arthritis
-Mesenteric lymphadenitis
-Ulcerative typhlocolitis
-Vertebral osteomyelitis
-Uveitis
-Cutaneous absecesses

Front 269

Erysipelothrix rhusiopathie

Back 269

-Small gram+ slender rods
-can appear filamentous if rough colonies are stained
-Usually grows as a small clear alpha-hemolytic
-Coagulase positive (differentiates from listeria and corynebacterium)

Front 270

Erysipelothrix rhusiopathiae Habitat

Back 270

-Mostly pathogenic to swine and poultry
-30-50% of swine can be carriers, source of infection to susceptible swine
-Infections can be endogenous
-Infected animals shed bacterium in urine, feces, saliva, and vomitus
-Bacterium can survive in alkaline soil
--soil can be source of exogenous infection
-Fresh and salt water fish harbor bacterium on scales

Front 271

Erysipelothrix rhusiopathiae Virulence and Pathogenesis

Back 271

-Organism enters host via oral, cutaneous, or respiratory route
--oral is most common
-Contaminated semen can be source in turkeys
-Virulent strains are more adherent than non-virulent strains
-Virulence is associated with hemoagglutination and neuraminidase activity

Front 272

Neuraminidase in Erysipelothrix rhusiopathiae

Back 272

-Removes NANA from mucin, fibrinogen, RBCs
-Increases viscosity of blood
-Activates complement mediated hemolysis and extensive coagulopathy
--as seen in acute infection

Front 273

Erysipelothrix rhusiopathie disease in Swine

Back 273

-Piglets 3-18 months most susceptible
-Can be more than one form in an outbreak
-types:
--acute septicemic
--subacute septicemic
--chronic
-Chronic form can be classic vegetative endocarditis with or without non-supprative erosive arthritis

Front 274

Acite septicemic erysipelothrix rhusiopathie in Swine

Back 274

-Sudden occurrence of high fever
-Associated with endotoxin and peptidoglycan
-Clinical signs: inappetence, depression, conjunctivitis, vomiting
-Can lead to coma and death
-Hemorrhagic ulcers of stomach and small intestine mucosa are common

Front 275

Subacute septicemic Erysipelothrix rhusiopathie

Back 275

-Most characteristic form of the disease
-Can develop pathognomonic urticarial lesions
--rhomboidal or diamond pattern skin disease
-Necrosis of defined areas of skin
--peel off and leave ulcer

Front 276

Erysipelothrix rhusiopathie in other animals

Back 276

-Birds: Turkeys susceptible to infection leading to sudden death
--high mortality
--Diarrhea, massive petechial hemorrhages, gut is filled with blood
-Lab mice and pigeons: highly susceptible
--septicemia is commonly seen
-Calves and lambs: polyarthritis in 2-3 month old animals
--wound infection is mode of transmission

Front 277

Diagnosis of Erysipelothrix rhusiopathie

Back 277

-Clinical signs
-Isolation and identification is essential for infection diagnosis
-Pathognomonic lesions (rhomboidal/diamond)

Front 278

Treatment and control of Erysipelothrix rhusiopathie

Back 278

-Antibiotics: penicillins, tetracycline, streptomycin
--resistant to kanamycin and sulfadimethoxazine
--Antiserum is effective prophylactically and therapeutically
-Vaccine can also be effective

Front 279

Listeria monocytogenes background

Back 279

-Major food-borne disease due to severity
-Causes meningitis, septicemia, abortion
-NOT in the gut
-high fatality rate (20-30%)
-First reported during WWI

Front 280

Listeria monocytogenes Morphology

Back 280

-gram+ short rods (appear and cocci)
-Motile
-Non-sporing
-Non-capsulated
-Aerobic/facultative anaerobic
-Resistant to low pH and high NaCl environments
-Facultative intracellular organism

Front 281

Listeria monocytogenes virulence factors

Back 281

-Internalin: allows attachment to host epithelial cells
-Listeriolysin O: enables listeriae to escape from host cell phagosome, allows bacteria to escape
-Act A: allows recruitment of host cell actin filaments
-Siderophores: allow scavenging of iron from transferrin

Front 282

Listeria pathogenesis

Back 282

-Surface protein internalin interacts with E-cadherin on epithelial cells
-Induces phagocytosis
-Epithelial cells do not usually undergo phagocytosis
-Listeriolysin O lyses phagolysosomal membrane, bacteria escapes into cytoplasm and avoids intracellular killing
--lysosome fusion does not occur
-Bacteria divides in cytoplasm, doubles in 1 hour
-Virulence factor Act A induces host cell actin polymerization
--Actin filaments propel bacteria to host cell membrane
-Listeria hijacks contractile system of the host cell for cell-cell migration

Front 283

Listeria mechanism of action

Back 283

-Causes epithelial cells to take in bacteria
-phagolysosomal membrane is broken by bacteria and bacteria leaks into cytoplasm
--bacteria divides and multiplies
-Uses host cell actin to polymerize bacteria
-Bacteria has actin filaments to move around within the cell and between cells
-Moves between cells without being exposed to antigens, antibodies, complement, or neutrophils
-Life cycle begins again in the new cell

Front 284

Stages in Listeria monocytogenes life cycle

Back 284

1. enters host epithelial cell
2. breaks out of phagolysosome
3. multiplies within cell
4. takes over actin of host cell, develops actin-based motility
5. Spreads to adjacent cells

Front 285

Listeria and Iron

Back 285

-Siderophores allow scavenging of iron from transferrin
-Transferrin is taken from the host cell and turned into iron
-Iron enhances growth of listeria organisms
-Will have increased lethality with iron supplements, iron feeds bacteria

Front 286

Pathophysiology of Listeria infection

Back 286

1. Listeria from fecal shedding or soil enters GI tract
-Causes febrile gastroenteritis
2. Listeria translocates to liver
-causes sub-clinical pyogranulomatous hepatitis
-initiates immune response
3. Bacteremia spreads to brain (meningioencephalitis), placenta (placentitis, abortion, and neonatal septicemia), and body (septicemia

Front 287

Clinical implications of Listeria pathogenesis

Back 287

-Listeria invades GI tract without erosive lesions
-Negative gram stain in cerebral spinal fluid
-Invades cerebral cortex and placenta
-Causes persistent infection despite antibiotic treatment
-Increased incidence in host with defective cell-mediated immunity
--cell immunity is important for killing pathogens

Front 288

Listeria clinical signs in Humans

Back 288

-Adults can be asymptomatic
-Mild influenza-like illness
-GI symptoms
-Meningitis in immunocompromised patients and pregnant women
-Bacteremia, fever, chills
-Can be deadly in immunocompromised individuals and neonates

Front 289

Listeria disease in Animals

Back 289

-Worldwide occurrence
-Almost all domestic and wild animals are susceptible
-Sheep, goats, and cattle are most severely affected
-Can cause encephalitis, meningoencephalitis, abortion, fetal damage, or stillbirths
-Animal will walk aimlessly in circles due to lesions in brainstem
--Can eventually result in cranial nerve paralysis

Front 290

Listeric Mastitis

Back 290

-bacterial organisms are shed in milk in somatic cells
-4% of raw milk samples contain Listeria monocytogenes

Front 291

Laboratory diagnosis of Listeria monocytogenes

Back 291

-Culture blood or CSF on conventional media
-Can use selective media or cold enrichment if other organisms outgrow listeria
-Can use enrichment broth
-Selective agents
-Beta hemolysis on sheep agar
-Tumbling motility

Front 292

Listeria treatment, prevention, and cure

Back 292

-Penicillin or Ampicillin
--either alone or in combination with gentamycin
-POTENT antibiotics
-No vaccine available
--bacteria is transmitted directly from cell-cell, never exposed to antibodies
--humoral immune reaction would not have an effect

Front 293

Listeria epidemiology

Back 293

-Important cause of zoonoses, especially in herd animals
-Only Listeria monocytogenes affects humans
-Common in soil, decaying vegetation, fecal flora of many mammals
--includes 15% of healthy adults
-Found in food
--raw vegetables, raw milk, fish, poultry, meats (deli meats)
-2nd most common cause of death due to food-borne pathogens

Front 294

Foodborne bacterial pathogens in the U.S.

Back 294

1. Salmonella (eggs, poultry, meat)
2. Listeria monocytogenes (ready-to-eat foods)
3. parasitic
4. viral
5. Campylobacter jejuni (poultry, raw milk)

Front 295

Seven questions about Phagocytosis

Back 295

1. How is the host alerted to the presence of bacteria
2. What cells are involved in phagocytosis
3. What directs phagocytes to site of infection
4. How is phagocyte recognition of bacteria amplified
5. How do phagocytes kill microbes
6. How do microbes avoid being killed
7. How can the immune response to bacteria be pathogenic

Front 296

Danger hypothesis

Back 296

-Danger in cells is sensed by Pattern Recognition Receptors (PRR)
--recognize Pathogen-Associated molecular patterns (PAMPS)
-Immune system has to decide whether to respond
-Allows discrimination between self and non-self
-Immune system decides how to respond
-Damage to site of infection is important for rapid initiation of an immune response

Front 297

PAMPS

Back 297

-Pathogen-associated molecular patterns
-Molecules on surface of antigen
-Peptidoglycan lipoproteins, mycoplasma lipoprotein, lipopolysaccharide, flagellin, CpG DNA

Front 298

Receptors and responses of phagocytic cells

Back 298

1. 7 alpha helical tmr
-cause increased integrin avidity and cytoskeletal changes
-Allows macrophages to migrate into tissues
2. Toll-like receptors
-produce cytokines and reactive oxygen intermediates
-Kills microbes
3. Mannose receptor
-produces cytokines and ROI
-Allows phagocytosis of microbe into phagosome
-Kills microbes

Front 299

Fc Receptors

Back 299

-Only macrophages have Fc receptors
-Also have C' receptors
--CR1 binds to C3b
--CR2 binds to iC3b

Front 300

Toll-like receptors

Back 300

-Key role in defense system of plants, insects, and vertebrates
-Recognition and signaling system originally discovered in fruit-fly
-Recognize PAMPs and activate MyD88
-9 TLRs in mammals
--bind to different molecules associated with microbes
-Transmit signal to the cell via NF-kB
-Leads to cell activation and production of cytokines

Front 301

Monokines

Back 301

-IL1
-IL8
-TNF-a
-IL6
-IL12

Front 302

IL-1

Back 302

-Activates vascular endothelium
-Activates lymphocytes
-Causes local tissue destruction
-Increases access of effector cells
-Causes fever and production of IL-6

Front 303

IL-8

Back 303

-Chemotacticc factor for leukocytes
-Increases access of effector cells

Front 304

TNF-a

Back 304

-Activates vascular endothelium
-Increases vascular permeability
-Leads to increased entry of IgG, complement, and cells
-Increases fluid drainage to lymph nodes
-Causes fever, mobilization of metabolites, and shock

Front 305

IL-6 and IL-12

Back 305

-Lymphocyte activation
-Increased antibody production
-Cause fever
-Induce acute phase protein production

Front 306

Phagocytes

Back 306

1. neutrophils: circulate in blood
--invade sites of inflammation
--short life span
2. Macrophages: monocytes in blood, mature to macrophages in tissue
--long life span
--Slightly larger

Front 307

Types of macrophages

Back 307

-Alveolar macrophages (lung)
-Histiocytes (connective tissue)
-Kupffer cells (liver)
-Mesangial cells (kidney)
-Microglial cells (brain)
-Tissue macrophages
-A cells (synovial fluid)
-Monocytes (blood)

Front 308

Trout phagocytic B-cells

Back 308

-Large, nucleated, with small cytoplasm

Front 309

Trout granulocytes

Back 309

-large cytoplasm
-Small nucleus

Front 310

Murine phagocytic B-cells

Back 310

-2 types of B-cells
-B-cells of mammals are highly phagocytic
-Present antigen better than macrophages
-B-cells are conserved throughout evolution
--fish and sharks also have B-cells

Front 311

Factors directing macrophages to site of infection

Back 311

-Anaphylotoxins (C3a, C5a)
-Macrophage derived cytokines
--IL-1, IL-8
-Adhesion molecules
-Chemokines

Front 312

Anaphylotoxin C5a

Back 312

-Most potent anaphylotoxin
-Chemotactic function
-Attracts phagocytes

Front 313

Cell migration into inflammatory sites

Back 313

1. rolling adhesion
-E-selectin expressed on vascular endothelium, activated by TNF
2. tight binding
-ICAM-I on endothelium binds to monocyte in the blood
3. diapedesis
-Monocyte migrates into the tissue through fenestrations and becomes a macrophage
4. Migration
-Chemokines bind to IL-8 receptor and C5a receptor on macrophage
-Macrophage moves down chemotactic gradient to site if inflammation

Front 314

Adhesion molecules

Back 314

-Selectins
-Carbohydrate ligands for selectins
-Integrins
-Immunoglobulin superfamily

Front 315

Selectins

Back 315

-Bind to cell surface carbohydrates
--mucin-like molecules (vascular addressins)
-P and E selectins expressed on activated vascullar endothelium
--activated by TNF
--bind to sialyl Lewisx on lymphocytes

Front 316

Integrins

Back 316

-Mediate adhesion between cells and between cells and ECM
-Composed of alpha and beta chains that pair non-covalently
--loose connection
-LFA-1 on cell binds to ICAM on endothelium
-VLA-4 on cell binds to VCAM on endothelial surface

Front 317

LFA-1

Back 317

-Leukocyte function associated agent-1
-Found on most leukocytes
-Binds to ICAM (intracellular cell adhesion molecule)
-Covalent interaction, tight binding

Front 318

VLA-1

Back 318

-Very late activation agent
-Found on most leukocytes
-Binds to VCAM on endothelial surface
-Tight binding, covalent interaction

Front 319

Immunoglobulin Superfamily

Back 319

-ICAM: intracellular adhesion molecules, expressed on endothelium
--Bind to integrin LFA-1

-VCAM: expressed on activated vascular endothelium
--binds to integrin VLA-4 on leukocyte

Front 320

Chemokines

Back 320

-Large family of proteins
-Can be produced by many different cell types, all with related amino acid sequence
-CC group:
--2 adjacent cysteines
--promote migration of monocytes
-CXC group:
--cysteines separated by another amino acid
--promote migration of neutrophils

Front 321

Chemokines

Back 321

-IL-8
-MIP-beta
-MC-1
-Rante

-Induce stable binding between cells in the bloodstream and endothelium
-Activates lymphocytes
-Anti-angiogenic or angiogenic

Front 322

IL-8

Back 322

-CXC cytokine
-produced by monocytes, macrophages, fibroblasts
-Acts on neutrophils

Front 323

MIP-beta

Back 323

-CC chemokine
-Produced by monocytes, macrophages, neutrophils, and vascular endothelium
-Acts on CD-8 T-cells

Front 324

MC-1

Back 324

-CC chemokine
-Produced by monocytes, macrophages, and fibroblasts
-Acts on T-cells and monocytes

Front 325

RANTE

Back 325

-CC chemokine
-Produced by T-cells
-Acts on other T-cells and monocytes

Front 326

Amplification of phagocyte activation and recognition

Back 326

-Opsonins
-Acute phase proteins

Front 327

Opsonins

Back 327

-Amplify phagocyte recognition and activation
-coat pathogens
-Allows pathogens to be taken up by receptors

Front 328

Acute Phase Response

Back 328

-Shift in proteins secreted by the liver into the blood
-Shift occurs due to action of IL-1, IL-6, and TNF on hepatocytes
-C-reactive protein
-Mannose binding protein
-Serum amyloid protein
-Fibrinogen

Front 329

Acute phase response step-by-step

Back 329

1. bacteria induce macrophages to produce IL-6
2. IL-6 acts on liver to induce production of acute-phase proteins
3. Serum amyloid protein, C-reative protein, fibrinogen, and mannose-binding protein produced
4. Acute phase proteins activate complement and opsonize bacteria

Front 330

Phagocyte killing of macrophages

Back 330

-Ingestion of microbe
-Production of enzymes (peroxidase, phosphatases, nucleases, lysozymes, cathepsins, etc.)
-Production of defensins
-Acidification in phagolysosome, low pH
-Activation of respiratory burst
-Release of nitric oxide

Front 331

Enzymes in phagocytes

Back 331

-Peroxidase
-Phosphatases
-Nucleases
-Lysozyme
-Cathepsins

Front 332

Defensins

Back 332

-Cationic peptides
-30-35 aa long
-Rich in cysteine, arginine
-Have antibiotic activity
-Form pores in cell membranes

Front 333

Phagocytosis

Back 333

-infloding of plasma membrane with bacteria attached
-Occurs due to contraction of actin and myosin filaments
-Triggered by attachment of bacteria to the cell surface
-Depends on recognition of receptors, needs receptors in order to recognize and bind to bacteria
-Microbes are killed by fusion of phagosome with lysosome
--forms phagolysosome
-Killed by lysosomal enzymes, NO, or ROI

Front 334

Respiratory burst

Back 334

-Phagocytosis of bacteria by neutrophils and macrophages leads to cascade of reactions, end result is production of toxic oxygen radicals

Front 335

Nitric Oxide production

Back 335

-Produced in a series of reactions
-Requires inducible nitric oxide synthase (enzyme)

Front 336

Microbe avoidance of destruction

Back 336

-Kill phagocyte first
-Inhibit phagocyte activity
-Inhibit lysosomal fusion with phagosome
-Escape from phagosome
-Develop mechanisms to survive inside phagolysosome

Front 337

Microbes killing phagocytes

Back 337

-Release hemolysins
-Lyse RBCs and are toxic for macrophages and PMNs
-Streptococci
-Causes cell to explode

Front 338

Microbe inhibition of Phagocytosis

Back 338

-M-proteins on Sterptococci
-Polysaccharide capsules on pneumococci
-Capsule is very important for long-term survival of bacteria
-Unencapsulated bacteria are coated with C3b

Front 339

Microbe inhibition of lysosomal fusion

Back 339

-Mycobacterium and Salmonella can inhibit fusion between phagosome and lysosome
-Mechanisms are not totally clear

Front 340

Microbe escape from the phagosome

Back 340

-Listeria monocytogenes: bacteria taken up by macrophages into phagosomes
--many bacteria are killed
-After acidification of phagolysosome listeriolysin enzyme is activated
--leads to lysis of phagolysosomal membrane
-Bacteria is able to get into cytoplasm

Bacteria lyses phagolysosomal membrane and gets into the cytoplasm

Front 341

Microbe resistance to killing

Back 341

-Salmonella, Brucella, Yersinia are able to survive within the phagolysosome
-Phagolysosome is formed but bacteria is not killed

Front 342

How can immune response to bacteria be pathogenic?

Back 342

-Too many bacteria, MASSIVE immune response is activated
-Bacteria spread to bloodstream, causes sytemic release of TNF
-Causes vasodilation and increased vascular permeability, disseminated intravascular coagulation
-Leads to loss of clotting ability and eventual failure of internal organs
--kidney, liver, heart and lungs
-Cytokine storm

Front 343

Enterobacteriaceae general properties

Back 343

-Gram-
-Rod-shaped bacteria
-Facultative anaerobes, grow in presence of O2 (can also ferment aerobically)
-Widely distributed in intestine, plants, soil, water
-Coliforms
-Species-specific range of niches, hosts, and infectious processes
-Large capacity for antibiotic resistance

Front 344

Organisms in GI tract

Back 344

-Stomach, duodenum, and jejunum are mostly gram+ flora
-Ileum is a mix between gram+, coliforms, and anaerobes
-Colon is mostly anaerobes, lots of coliforms, and gram+ flora
-Most bacteria in GI system is in ileum and colon
-Least bacteria in GI system is in stomach, duodenum, and jejunum

Front 345

Escherichia coli

Back 345

-Live in warm-blooded hosts (vertebrates)
-In intestines, distal ileum to the colon, part of normal intestinal flora
-Virulent and avirulent strains exist
-Asymptomatic carriers are the source of virulent strains
--adults immune hosts
-Many variants give rise to many disease processes, can have 30% variation in DNA between strains

Front 346

Enteric colibacillosis

Back 346

-diarrhea
-Occurs in neonatal pigs, ruminants, rabbits, humans, dogs, and cats
-Nursing and weaning pigs are susceptible due to increased stress factors and change of diet

Front 347

Enterotoxigenic E. Coli
ETEC

Back 347

-Entertoxigenic, causes watery diarrhea
-Toxin is secreted into intestinal lumen, binds to receptors on enterocyte cell surface
-Translocates into enterocytes
-bacteria itself remains in the gut
-Virulence factors: colonization factors
--fimbral adhesins to bridge between host cell and bacterial cell
--allows local multiplication
-Enterotoxins result in massive release of Cl, Na, H20, K, HCO3 out of enterocytes and into intestinal lumen
-Major loss of electrolytes
-Enterocytes shrink because they lose all of their water

Front 348

Enteropathogenic E. coli
EPEC

Back 348

-Type III secretion system/needle
-Direct injection from bacteria into the host enterocyte
-Results in subversion of cytoskeletal machinery, changes signal transduction mechanisms in the cell
--results in attaching and effacing lesions
--Loss of microvilli of enterocytes
--Effacement and cupping

Front 349

Enterotoxigenic E. coli enterotoxins

Back 349

-Heat-labile toxins:
--1A and 5B subunits
--Once in cell will increase cAMP, Cl secretion, Na absorption
-Heat-stable toxin: peptide
--results in cGMP

Front 350

Enterotoxigenic E.coli toxin binding mechanism

Back 350

-5B domain binds to enterocyte cell surface
-Active domain is delivered into cell
-Active domain is cleaved inside the cell, activates G-protein and adenylate cyclase

Front 351

Enteropathogenic E. coli attaching and effacing

Back 351

-Endotoxin injection into host cell allows bacteria to take control of cytoskeletal machinery
-Polymerized actin forms pedestal under attached bacteria
-membrane of the host cell forms pedestal
-bacteria injects own receptor into host cell membrane
-Linker molecules interact with bacteria and result in actin polymerization
-Pedestals invade along the surface of the gut, colonize new areas

Front 352

Induction of Diarrhea with enteropathogenic E. coli

Back 352

-Decreased microvilli results in decreased absorptive surface area
-Actin is used in pedestals, not in tight junctions between cells
-Effector molecules will induce inflammatory responses, PMN recruited to the site

Front 353

Shigatoxin Producing E. coli

Back 353

-Type III effector molecule
-Also have shiga-toxin
--5 binding domain specific for receptors in humans
--not toxic to ruminants, ruminants are carriers
-Cause hemorrhagic colitis, Hemolytic urenic syndrome, thrombotic thrombocytopenic purpera

Front 354

Shigatoxin reserviors

Back 354

-Bovine food products
-Crops
-Water
-Other farm animals and wild animals
-Petting zoos
-Human-to human contact

Front 355

Pig edema disease

Back 355

-E. coli enterotoxemia
-Vasotoxin, affects blood vessels
-Arteriopthy, edema
-Neurological disorders in weaned pigs caused by toxin in the brain
-Attacks endothelial cells, especially kidney cells

Front 356

Adherent-Invasive E. coli

Back 356

-Cause granulomatous colitis
-Some dog breeds are pre-disposed
-Have specific types of fimbriae
-Can invade cells and cause thickened and ulcerated mucosa

Front 357

Non-enteric E. coli infections

Back 357

-Septicemia
-mastitis
-Urinary tract infections
-Nosocomial infections

Front 358

E. coli septicemia

Back 358

-Usually in early weeks of life
-Due to antibody deficiency
-NEED colostrum to prevent
-Important in chickens, can cause polyserositis

Front 359

E. coli mastitis

Back 359

-Lactating cows and sows
-Acute infection
-Toxemia symptoms

Front 360

Nosocomial infections

Back 360

-infections in hospitals, tend to be very resistant

Front 361

E. coli virulence factors

Back 361

-Capsules
--antibactericidal and antiphagocytic
-Lipopolysaccharides

Front 362

Lipopolysaccharide interaction with macrophages and dendritic cells

Back 362

-Binds to proteins, proteins bind to receptors that activate cytokines
-TNF, IL-1, IL-6
-Activation of cytokines can be important, can also cause cytokine storm

Front 363

Results of endotoxin in small amounts

Back 363

1. macrophage and monocyte activation
-leads to acute phase proteins and fever
-Can help eliminate infectious agents
2. B-lymphocyte activation
-increases antibody synthesis
3. Complement activation
-leads to inflammation

Front 364

Result of endotoxins in large amounts

Back 364

-Very Bad!
-Leads to shock and disseminated intravascular coagulation
--entire system coagulates

Front 365

Iron sequestering systems
Siderophore

Back 365

-Bacterial cell competes with host for transferrin and lactoferrin
-Inhibits respiratory burst in phagocytic vacuoles

Front 366

Hemolysins/cytolysins

Back 366

-cause transmembrane pores
-Very active on neutrophils
-induce cytokines and inflammatory response
-Primary target is lymphocytes

Front 367

Cytotoxins

Back 367

-Cytotoxic necrotizing factors
-Deaminate small GTPase rho, leads to constitiutive activation

Front 368

Uropathogenic E. coli

Back 368

-UTI diseases
-Females are more susceptible due to short urethra
-E. coli bind to surface of transitional cell epithelial layers
-LOTS of receptors on endothelium for bacterial fimbriae
-Bind and induce uptake of bacteria into transitional cell epithelium
-bacteria replicate
-Bacteria cause exfoliation of surface layer cells
--can then infect next layer down
-Recurrent infection, have to completely eliminate any toxins present to get rid of issue

Front 369

Laboratory diagnostics for E. coli

Back 369

-Isolation biochemical properties
-Serology for antigenic capsule
--O antigen (LPS)
--K antigen (capsule
--H antigen (flagella)
--Fimbral antigen
-DNA characterization
-Toxin identification

Front 370

E. coli therapy and prevention

Back 370

-Treat diarrhea with fluid and electrolyte replacement
-Immunizations
-Treat shock
-Use antibiotics that are not susceptible
-Hygiene is best prevention!
--food, feces, flies, (feces feces feces)

Front 371

Salmonella

Back 371

-Enterobacteriaceae
-Reservoir is intestinal tract in humans
-All salmonella are pathogens of warm-blooded animals
-transmitted via contaminated water or food, contaminated with feces
-Human pets can transmit
-Meat, milk, eggs can carry pathogen
-Can live for 3 weeks in water, months in dry feces
-ALL chickens have salmonella

Front 372

Salmonella disease and pathogenesis

Back 372

-Bacteremia or septicemia based on host
-Gastroenteritis is not host specific
--can be acute, chronic, latent, unapparent
-Carrier state will have asymptomatic shedders
-Farm animals are great reservoir for human salmonellosis

Front 373

Host-restricted Salmonella septicemia

Back 373

-Salmonella typhi: causes typhoid fever in humans
-Salmonella gallinarum and S. pullorum: in eggs of chickens
-Salmonella abortusovis: in lambs, causes abortions
-Salmonella abortusequi: in foals, late abortion

Front 374

Host-adapted Salmonella septicemia

Back 374

-All can also get into humans
-Salmonella dublin: in calves
-Salmonella choleraesuis: weaned and young pigs
-Salmonella typhimurium: rodents, pigeons
--reservoir is contaminating feeds
--usually not lethal

Front 375

Salmonella Virulence factors

Back 375

-Environmentally regulated
-Flagella, very active
-Fimbriae interact with intestinal epithelial cells and M-cells in peyer's patches
-Invasion: injection of bacterial proteins
--can take over cytoskeletal machinery and signal transduction mechanisms
-Results in macropinocytosis (formation of blebs, ruffles, splash)

Front 376

Salmonella invasion of an epithelial cell

Back 376

1. Translocation through and M-cell
2. Transepithelial migration
3. Luminal capture by dendritic cells

Will subvert cell machinery to create vacuole and are transported to other side of cell membrane
-are taken up by dendritic cells
-inside dendritic cells, migrate to lymph nodes

Front 377

Needles on surface of salmonella

Back 377

-Only expressed on contact
-Can grow very long
-Span membranes
-Looks like a syringe
-made out of proteins
-Inject proteins into needle

Front 378

Salmonella spreading

Back 378

-Survives and multiplies in macrophages
-Can also go into dendritic cells
--activates dendritic cells to produce chemokine receptors that attract them to lymph nodes
-Spread to regional lymph nodes, spleen, liver, and hematogenous dissemination
-LPS prevents deposition and activation of complement
-Iron sequestering systems are activated
-Salmonella-containing vacuoles are resistant to lysosomes
--creates micro-environment and divides

Front 379

Salmonella Pathogenesis steps

Back 379

1. ingestion of salmonella typhi
2. Gets into small intestine, spreads to lymphatics via M-cells
3. Migrates to mesenteric lymph nodes, causes transient primary bacteremia
4. Multiplies in macrophages (in spleen, liver, bone marrow)
5. Causes septicemia
6. Also gets into gallbladder, causes cholecystitis
7. Also goes into bile, back to small intestine, and inflames/ulcerates peyer's patches
--causes diarrhea, hemorrhage, perforation

Front 380

Salmonellosis

Back 380

-Gastroenteritis
-Can be ubiquitous: not host specific
--Salmonella typhimurium, salmonella enteritidis
-Injected salmonella proteins stimualte Ca and inositol polyphosphate fluxes
--leads to Cl secretion
-Induces an inflammaotry response via cytokines and infiltration of PMNs

Front 381

Salmonellosis steps

Back 381

1. Salmonella invades epithelial cells (15 min)
2. Neutrophils extravasate, vascular permeability increase leads to edema (1 hour)
3. Neutrophil induced tissue damage leads to epithelial detachment and beginning of fluid accumulation (3 hours)
4. Effusion of a large amount of neutrophils and protein-rich fluid into intestinal lumen (8 hours)
5. Pseudomembrane formation and diarrhea (12-48 hours)
--liquid flows from the blood to the intestinal lumen

Front 382

Salmonella laboratory diagnostics

Back 382

-Biochemical properties
-Serology (more than 2000 named serotypes)
--serotype is used to find species
--O-antigen and H-antigens
-Epidemiological suveys

Front 383

Salmonella therapy and prevention

Back 383

-Primary infections can be hit with wide spectra antibiotics
-For carriers and diarrhea antibiotics are not recommended, will remove competing microflora
-Fecal cultures
-Hygiene and disinfection
-pasteurization of milk
-Vaccines for humans, chickens, swine

Front 384

Yersinia

Back 384

-Straight rods or cocccobacilli (pleiomorphic)
-Grow optimally at 28C
--slow growth
-Facultative intracellular pathogens, prefer to be extracellular
-Inject molecules into host cells with contac

Front 385

Yersinia pestis

Back 385

-Black death, black plague
-Most current cases are in sub-Saharan Africa, some in china and Peru
-In U.S., most cases are reported in 4-corners region/ intermountain west and california
--due to presence of prairie dog intermediate host with flea vectors
--Cats interact and spread
--usually 5-15 cases per year
-Early treatment is key!

Front 386

Yersinia pestis diseases

Back 386

-Lymphadenitis: buboes, swollen lymph nodes
-Pneumonic plague
-Hemorrhagic sepsis

Front 387

Yersinia pathogenesis

Back 387

-3 plasmids
-Antiphagocytic and cytotoxic proteins injected into host cell
-Plasminogen activator protein
-Capsule protein
-Proteins to acquire iron
-LPS
-"Stealth technology"

Front 388

Yersinia laboratory diagnosis and treatment

Back 388

-yersinia is non-motile at all temperatures
-inactive in routine biochemical tests
-treat with streptomycin, tetracyclin
-Prevent with education, rodent control, insecticides, and repellents

Front 389

Yersinia pseudotuberculosis

Back 389

-Rodent, smammals, and bird reservior
-Transmitted via direct or oral route
-Can survive in soil
-Causes acute sepsis, pseudotuberculosis, acute abdominal syndrome in humans
--mesenteric lymphadenitis
--chronic, multiple small abscesses in lymph nodes and organs

Front 390

Yersinia pseudotuberculosis virulence factors

Back 390

-Adhesins and invasins
-Plasmid-encoded antiphagocytic and cytotoxic proteins injected into host cells
-Iron regulated proteins

Front 391

Yersinia pseudotuberculosis treatment and prevention

Back 391

-Can treat with antibiotics, but usually it is too late
-Can prevent with vaccine

Front 392

Proteus mirabilis and Proteus vulgaris

Back 392

-Enterobacteriaceae forms
-Otitis externa and UTIs in dogs
-Has urease and flagella
-Polymyxin and nitrofurantoin resistant

Front 393

Klebsiella pneumoniae

Back 393

-Attacks mucosa of animals and humans
-Can exist in the genital tract (causes metritis and abortion)
-Respiratory tract of horses, swine, dogs
--follows a viral infection
-Causes diarrhea in calves
-Has a capsule
-Is ampicillin resistant, NEVER treat with ampicillin

Front 394

Enterobacter aerogenes, Enterobacter cloacae

Back 394

Enterobacteriaceae

Front 395

Serratia marcescens

Back 395

-Enterobacteriaceae
-Orange/red pigments on culture

Front 396

Cmpylobacter

Back 396

-Curved, spiral, or S-shaped gram- bacteria
-NOT an enterobacteriaceae
-Causes disease of the gut
-Motile with polar flagellum at one or both ends
-Oxidase positive
-Microaerophilic, needs low O2 (3-6%)

Front 397

Thermophilic Campylobacter

Back 397

-Grows at 45C
-Avians have increased body temp
-Present in commensals in the intestines of birds mostly
--can also exist in some adult mammals
-Campylobacter jejuni in chickens and cattle
-Campylobacter coli in pigs
-Causes abortion, mastitis, enteritis in cattle
-Enteritis in young dogs and humans

Front 398

Campylobacter jejuni response in humans vs. chickens

Back 398

-Humans: causes inflammation and diarrhea
-Chickens: no inflammation

Front 399

Environmental reservoirs for Campylobacter jejuni

Back 399

-Chicken intestinal mucosa
-Contaminated water, associated with fresh water amoebae
-Unpasteurized milk
-Poorly cooked meat

Front 400

Cmpylobacter jejuni virulence factors

Back 400

-Non-fimbral adhesins
-N and O glycosylated surface structures
--lipooligosaccharide
--capsule
--host ganglioside minicry
-Flagella allows colonization and secretes proteins involved in invasion
-Cytolethal distending toxin causes DNA damage and cell cycle arrest
-Type IV secretion system for transformation competence

Front 401

Campylobacter fetus

Back 401

-Venereal disease in cattle
-Reservoir in preputial cavity of bulls and genital tracts of cows
--asymptomatic carriers
-Causes metritis, infected fetuses, abortion, infertility
-Prevent with AI

Front 402

Campylobacter fetus fetus

Back 402

-Reservoir in intestine of cattle and sheep
-Causes sporadic abortion in cattle and sheep
-in rare cases can cause abortion in humans
-S-layer has antigenic variations during an infection
--inhibits complement-mediated lysis and phagocytosis

Front 403

Lawsonia intracellularis

Back 403

-Gram-
-Curved bacteria with a single flagella
-Grows in 9% CO2 and 9% O2, both are needed for growth
-Causes proliferative enteropathy mostly in pigs
--acute hemorrhagic diarrhea in older pigs
--Intestinal adenomatosis in growing pigs
-Binds, invades, and escapes in the cytoplasm
-Diagnose with ELISA and PCR
-Control with antibiotics in feed and vaccines

Front 404

Pasteurella

Back 404

-Small gram- coccobacilli/bacilli
-Facultative anaerobe, like aerobic environments
-Grow better on blood agar

Front 405

Pasteurella multocida

Back 405

-Commensal bacteria, on mucosa of nasopharynx
-Opportunistic bacteria
-Host-adapted serotypes and biotypes
-Some serotypes are highly contagious
--cause hemorrhagic sepsis in cattle
--Fowl cholera, high mortality
-Cause respiratory tract infections in rabbits, cats, calves, pigs
-Causes abscesses in humans, dogs, cats by bites and scratches

Front 406

Virulence factors of Pasturella multocida

Back 406

-Pasturella multocida toxin
-Affects several signal transuction pathways, results in actin rearrangement
-Leads to bone loss, inhibits osteoblast activity and differentiation
-Has a capsule
-LPS
-Fimbriae

Front 407

Pasturella multocida laboratory diagnosis

Back 407

-Isolation on McConkey, hemolysis, biotyping
-Serology
-Most antimicrobial agents are effective therapy
-Prophylaxis fof serotype-specific bacterins

Front 408

Capnocytophaga carnimorsus

Back 408

-Facultative anaerobe, grows better with CO2
-Long, thin gram- rods
-slow-growing
-Oral cavity commensal bacteria in dogs and cats
-Can cause complication with bite wounds, may lead to spesis
-Virulence factors include sialidase, blocks macrophage killing, and LPS

Front 409

Mannheimia haemolytica

Back 409

-Can be a primary or secondary pathogen
-Very specific for ruminants
-Causes upper respiratory tract infections in ruminants
--shipping fever in cattle
--pneumonia, sepsis in lambs
-Causes pneumonia, salpingitis, and sepsis in fowl
-Causes mastitis in ewes
-reservoir in asymptomatic carriers of adult immune animals

Front 410

Mannheimia haemolytica virulence factors

Back 410

-Leukotoxins (hemolysin, cytotoxin)
-Specific for ruminant leukocytes and platelets
-Inflammatory
-LPS
-Induces inflammatory cytokines
-Capsule
-Fimbriae
-Membrane protein binds ruminant transferrin/iron

Front 411

Mannheimia haemolytica labratory diagnostics

Back 411

-McConkey positive, heolysis positive, 2 biotypes
-Serology will have somatic O-antigen and capsule
-Can vaccinate! Attenuated or subunit vaccines

Front 412

Haemophilus

Back 412

-Small gram- bacilli
-Facultative anaerobe
-Causes human meningitis (Haemophilus influenzae)
-LOS
-Requires hemin (factor X) or NAD (factor V)

Front 413

Haemophilus parasuis

Back 413

-Has reservoir in mucosa of normal pigs, exists on nasopharynx
-Causes Glasser's disease
-Occurs in 2 week-3 month old pigs
-Fibrinous polyserositis, polyarthritis, meningitis, sepsis
-Tx: penicillin
-Prophylaxis with bacterins
-Many serovars

Front 414

Histophilus somni

Back 414

-Reservoir in cattle, asymptomatic carriers
--exist on respiratory mucosa and in genital tract
-Causes respiratory diseases in calves
-can cause endometritis and abortion in cows
-Thromboembolic meningoencephalitis in cattle

Front 415

Thromboembolic meningoencephalitis

Back 415

-In cattle
-Bacteria invade respiratory tract and migrate into blood
-Cause bacteremia in blood
-Damages vascular endothelium, causes platelet aggregation and coagulation, leading to thrombosis
-Can also go into joints and cause arthritis
-Typical with Histophilus somni

Front 416

Histophilus somni virulence factors

Back 416

-Surface proteins bind to bovine transferrin/iron
-LOS shows phase variation
-Fc receptors with anti-phagocytic effect, prevents activation of complement and opsonization
-Resist neutrophils
-intracellular survival in bovine macrophages
--inhibits respiratory burst
-Resistant to NO
-Culture requires thiamin pyrophosphate
-Tx: penicillin

Front 417

Taylorella equigenitalis

Back 417

-Contagious Equine Metritis
-Reservoir in asymptomatic carriers in stallions
-Venereal disease
-Causes endomtritis, cervicitis, and vaginitis
--Leads to abortion
-Swab to control contamination
-Very susceptible to environmental changes, fastidious organism
-Tx: penicillin

Front 418

Taylorella equigenitalis clinical signs

Back 418

-White, stringy mucous exudate from vagina
-Accumulation of muco-purulent exudate in uterus

Front 419

Actinobacillus

Back 419

-pasturella-like morphology
-Urease positive
-McConkey positive

Front 420

Actinobacillus pleuropneumoniae

Back 420

-Causes hemorrhagic necrotizing pneumonia with pleuritis
-In pigs
-Reservoir in chronic carriers, there are not healthy carriers
-Transmission via aerosol
-5-7 day incubation period
-Starts with checkerboard pattern of infection, will eventually destroy entire lung
-High morbidity
-lethality depends on environmental factors
-Survivors will have chronic pneumonia, will always be sick and will always infect other pigs

Front 421

Actinobacillus pleuropneumoniae virulence factors

Back 421

-Capsule antigen
-LPS leading to adhesion and inflammatory response
-Host-specific cytotoxin
-Necrotic vasculitis
-Hemorrhagic lesions
-Leukocidal
-Porcine transferrin binding protein
-Tx: penicillin (trimethoprim-sulfonamide)
-Vaccines do exist, serotype specific bacterins

Front 422

Actinobacillus lignieresii

Back 422

-Causes "wooden tongue" in ruminants
-Granulomatous abscesses around oral cavity in cattle
--involves sort tissue
-Gets in via small abrasions of oral mucosa
-Animals get thinner and thinner, do not eat normally
-Virulence is due to proteases
-Can treat with surgery or with antibiotics

Front 423

Actinobacillus equuli

Back 423

-"Sleepy foal disease"
-Pyosepticemia in newborn foals and piglets
-Results in nephritis, pneumonia, polyarthritis, enteritis
--multiple small abscesses in the kidney
-Carried in mare intestinal and reproductive tract
-Common with young animals that did not get adequate colostrum

Front 424

Actinobacillus suis

Back 424

-Similar to actinobacillus equi, but in suckling pigs

Front 425

Bordetella

Back 425

-Pathogens of the respiratory tract
-Gram- coccoid-oval bacilli (has different forms)
-Strict aerobes, do not ferment, NEED oxygen
-Like to grow on aa
-Bacteria stick to cells of respiratory epithelium

Front 426

Bordetella bronchiseptica

Back 426

-Causes tracheobronchitis, pneumonia, purulent rhinitis and conjunctivitis
-Kennel cough in dogs
-more rare in cats
-Rhinitis and bronchopneumonia in pigs, rabbits, guinea pigs, and other rodents
-Rhinitis atrophicans

Front 427

Rhinitis atrophicans

Back 427

-Bordetella bronchiseptica and pasturella multocida
-Infects pigs and rabbits
-Causes acute rhinitis, progressing to deformations in nasal turbinate bones, nasal septum, and upper jaw

Front 428

Bordetella bronchiseptica virulence factors

Back 428

-Colonizing factors
--filamentous hemagglutinin, pertactin, fimbriae
-Siderophore and transferrin/lactoferrin binding proteins
-Toxins
-Adenylate cyclase/hemolysin
-Type III secretion system, induces necrosis and affects immune response
-Type VI secretion system, leads to cytotoxicity
-Dermonecrotic toxin
-Tracheal cytotoxin

Front 429

Tracheal cytotoxin

Back 429

-Portion of cell wall murein
-Corresponds to structure of tracheal cytotoxin
-Inhibits Fe-S proteins ciliostasts extrusion of ciliated epithelial cells
-Causes cilia to stop moving, allows pathogens to get deeper into respiratory system

Front 430

Bordetella bronchiseptica lab diagnostics

Back 430

-McConkey positive
-Not fastidious
-Some pathogens are resistant to antimicrobials
-Vaccines are available
--intranasal vaccines
--attenuated strains

Front 431

Pseudomonas

Back 431

-Gram negative rod
-Gammaproteobacteria
-Obligate aerobe, needs O2
-Found ubiquitously in environment in water, soil, plants
-Also found on skin, mucous membranes, feces
-Opportunistic host, does not generally cause disease in immunocompetent and healthy hosts
-Individuals with cystic fibrosis are highly predisposed to pseudomonas infections

Front 432

Pseudomonas aeruginosa

Back 432

-Can be detected in GI and upper airway flora in normal healthy animals
-Glucose non-fermenter
-Can grow in temps up to 42C
-Resistant to environmental stresses, esp. high concentrations of salts and dyes, weak antiseptics, and commonly used antibiotics
-Can grow in diesel and jet fuel, uses hydrocarbons

Front 433

Pseudomonas aeruginosa characteristics

Back 433

-Gram-
-Oxidase+
-Blue-green pigmentation
-Smells like grapes, has sweet odor
-Motile
-Highly antibiotic resistant
-Produces different toxins responsible for disease

Front 434

Pseudomonas isolation agar

Back 434

-Used to isolate pseudomonas from wounds and clinical samples
-Resistant to Irgasan, a broad spectrum antibiotic
-Magnesium chloride and potassium sulfate produce pyocanin green pigment
-Without bacteria no color, bacteria turn plate green due to pigment

Front 435

Pseudomonas aeruginosa isolates

Back 435

-produce 3 colony types
1. Soil or water isolates: small, rough colony
2. Clinical samples: smooth colony types
-fried egg appearance
3. respiratory and urinary tract: mucoid appearance due to alginate slime
-importance for virulence of bacteria, produces biofilms and allows colonization

Front 436

Pseudomonas in Species

Back 436

-Cattle: mastitis, metritis, pneumonia, dermatitis, enteritis in calves
-Sheep: mastitis, fleece rot, pneumonia, otiotis media
-Pigs: respiratory infections, otitis
-Horses: genital tract infections, pneumonia, ulcerative keratitis (corneal ulcers)
-Dogs and cats: otitis, cystitis, pneumonia, ulcerative keratitis
Mink: hemorrhagic pneumonia, septicemia
-Chinchillas: pneumonia, septicemia

Front 437

Fleece rot in sheep

Back 437

-repeated wetting of wool without drying allows bacteria to proliferate
-Grows in wool and causes discoloration due to green pigment of bacteria
-Not a major problem for sheep health unless immunocompromised
-Economic impact on wool sales

Front 438

Pseudomonas virulence factors

Back 438

-Flagellum for motility
-Pilus for attachment to surfaces
-Alginate slime production, allows biofilm formation and avoidance of phagocytosis
-Produces endotoxins that resist host immune defense
-LPS and endotoxic shock

Front 439

Pseudomonas diagnosis

Back 439

-Isolate from pus, urine, milk, respiratory aspirate, ear swabs
-Growth on blood agar or McConkey agar
--incubate 37 degrees foor 24-48 hours
-Characteristic colony morphology with grape-like odor
-Pyocyanin pigment production
-Lactose negative
-Oxidase positive

Front 440

Pseudomonas Treatment

Back 440

-Pseudomonas is highly resistant to many antibiotics and disinfectants
-Has outer membrane that is relatively impermeable
-Expresses multi-drug eflux pumps that pump bacteria out
-Bacteria in biofilms are resistant to antibiotics
-Can use gentamycin and tobramycin with carbenicillin or ticaricillin
--antibiotic resistance is emerging
-Vaccines may be required for farmed mink and chinchillas
--lots of antigenic variation makes vaccines not super effective
-Polyvalent exotoxin A vaccine may be proective broadly

Front 441

Pseudomonas therapy and prevention

Back 441

-Culture for susceptibility testing
--spot culture certain animals
-Hygiene and aseptic procedures is important for preventsion

Front 442

Brucella cultural importance

Back 442

-Gram- bacterial pathogen
-Small coccobacilli
-Found in many environments, caused some major issues throughout the world
-highly contagious zoonotic infection
-Caused by ingestion of unpasteurized milk or meat from infected animals, or close contact with contaminated secretions from infected animals
-Human-human transmission is very rare
-Can be transmitted from mother to child at birth or transmammary

Front 443

Brucella species of importance

Back 443

-Brucella abortus
-Brucella melitensis
-Brucella suis

-Produce small, glistening bluish translucent colonies after incubation on blood agar

Front 444

Brucella overview

Back 444

-Small gram- coccobacilli
-Stain red using Ziehl-Nieelsen method
-Aerobic and capnophilic, can thrive in CO2 rich environments
-Non-hemolytic on blood agar
-Non-motile
-Catalase positive
-most are oxidase positive
-Urease positive
-intracellular pathogen that survives and replicates in host macrophages

Front 445

Brucella Epidemiology

Back 445

-Reportable zoonosis
-Hosts are humans, cattle, sheep, goats, swine, horses, dogs, chickens, wildlife
-Orally transmitted
-Venereal transmission, esp. at birth
--females will be asymptomatic until gestation
-Can be transmitted in milk or placenta
-Killed by drying, UV light, pasteurization or 60C for 10 minutes

Front 446

Brucella species by species

Back 446

-Brucella melitensis: goats and sheep
-Brucella suis: pigs, endemic in caribou
-Brucella abortus: cattle and bison, can also affect elk
-Brucella ovis: sheep
-Brucella canis: dogs

Has also been isolated from several marine mammal species

Front 447

Brucella transmission and humans

Back 447

-Can be transmitted to and by humans via contact with animals or animal products
-In milk
-By slaughter
-Via veterinary care
-Vaccination accident
-Laboratory accident

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Brucella pathogenesis

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-Brucella are phagocytosed and carried to reticuloendothelial tissue and reprotuction organs
-Supramammary lymph nodes
-Liver
-Spleen
-Bones and joints
-Survive and replicate to high numbers in macrophages

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Brucella virulence factors

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-Can grow on erythritol
-Siderophores to draw iron from host
-Lipid A and LPS are less endotoxic, cause less inflammation in the host
-Avoids innate immune response
-O-antigen prevent C3 complement binding
-Flagella lacks TLR5 agonist domain, modified and does not trigger immune response
-Intracellular pathogen that avoids cellular immunity

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Brucella type IV secretion system

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-Encoded by Vir proteins in bacteria
-Injects secreted factors that allow brucella to survive inside macrophage and avoid NO killing and inhibit phagolysosome fusion
-Prevents degranualtion and oxidative burst of neutrophils
-Survives and replicates to high numbers without triggering an immune response that would kill bacteria
-Grows to extremely high numbers in macrophages

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Brucella ovis

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-Causes infection and distortion of testis and epididymis in rams
-results in male sterility
-Inflammation of reproductive organs
-In females can cause spontaneous abortions
-transmission through ingestion of contaminated milk or contact with contaminated fluids

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Brucella abortus

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-Causes brucellosis in cattle and related animals
-Dairy herds in the US are treated at least once a year using Brucella Milk Ring test
-Confirmed cows are culled
-Young stock is required to be vaccinated to reduce zoonotic transmission
-Tattoo in ears proves vaccination status

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Brucella serology

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-Serum agglutination tests
-Tests for IgM to differentiate infections
-Milk ring test is very sensitive

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Brucella therapy and prevention

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-Humans and pets can be treated with doxycycline and rifampin or gentamicin
-Farm animals undergo eradication program, elimination of positive animals

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Brucella vaccination

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-Brucella abortus vaccine strain RB51 used in cattle
--O-antigen has been modified, allows identification of bacteria vs. vaccination

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Brucella eradication

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-Efforts began in 1930s
-Last remaining reservoir is in the GYE

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Brucella melitensis

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-Causes abortion, reduced milk yield, orchitis in goats and sheep
-Most readily transmitted to humans
-Persistent reproductive failure is sign of infection
-Abortions occur during last few months of gestation

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Francisella tularensis

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-Facultative intracellular gram- bacteria
-Pleomorphic
-Infects and replicates in macrophages and amoeba in environment
-replicates to high numbers in macrophages and amoeba
-Forms blue-tinged colonies on agar
-Important in biodefense

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3 major select bioterrorism agents

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1. Bacillus anthracis
2. yersinia pestis
3. Francisella tularensis

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Francisella tularemia pathogenesis

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-Reservoir: mice, rats, beaver, skunks, raccoons
-Pneumonic, bacteria inhaled
-Ulceroglandular (skin infections)
-Swollen lymph nodes
-Can be transmitted by animals that have been bitten by ticks, then transmitted to humans
-Mortality in humans is 30-60% if untreated

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Francisella tulatensis subspecies

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1. holarctica
2. tularensis
3. mediasiatica
4. novicida
--much higher infection rate in mice

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Francisella replication in macrophages

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-Can replicate to very high numbers inside macrophages
-bacteria make way into macrophages, macrophages eat bacteria
-bacteria enter into vacuole, then break out into cytoplasm of macrophages
-Eventually break out and infect new uninfected cells

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Francisella therapy

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-Aminoglycoside antibiotics
-Prevention is key
--use gloves and cover skin
-Attenuated live vaccine
-Immunity from vaccine usually leads to permanent immunity

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Moraxella bovis

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-Gram-, plump rod-shaped bacteria
-Coccoid
-diploid arrangement
-Commensal on mucous membranes of cattle
--in eye and respiratory tract
-Oxidase positive
-Hemolysis negative
-Small white colonies on blood agar
-Weakly beta hemolytic
-Commensal on mucus membranes
-Strict aerobe, needs high oxygenation
-Progressive, non-self limiting keratitis
-Most common in the summer in grazing cattle at high altitude

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Moraxella bovis pathogenesis

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-Causes infectious bovine keratoconjunctivitis
--Bovine pink eye
-Progressive, non-self limiting keratitis that can lead to ulceration and eventual rupture of the cornea
-Only infects cattle, but is related to Moraxella catarrhalis

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Moraxella catarrhalis

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-Commensal bacteria in humans
-Causes upper airway infections in humans that are immunocompromised
-related to Moraxella bovis

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Moraxella treatment

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-Subconjunctival injection of tetracycline
-Topical application of Cloxacillin

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Moraxella virulence factors

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-Fimbriae
-Capsule
-Hemolysin that is cytotoxic for neutrophils