Microbiology - Note Cards

Front 1

Coccoid (Coccus,Cocci) Bacteria are shaped as?

Back 1

Spherical

Front 2

Rod Shaped (Bacillus, Bacilli) Bacteria are?

Back 2

Cylindrical

Front 3

Vibrio Shaped bacteria are?

Back 3

Curved (Helical, Spiral)

Front 4

Is Square bacteria important?

Back 4

No, its not infectious.

Front 5

How would you call paired bacteria?

Back 5

Diplococci

Front 6

How would you call a bacteria in chain?

Back 6

Streptococci

Front 7

How would you call a cluster of bacteria?

Back 7

Staphylococci

Front 8

What about Tetrads of bactria?

Back 8

They are non-infecsious.

Front 9

Describe the gram stain procedure:

What is the critical Step?

Back 9

Steps:
- Flood w/ Crystal Violet
- Flood w/ Gram's Iodine
- Add Decolarizers (Acetone/Ethenol)
- Immediatly Rinse w/ water
- Flood with Safranin (Counter Stain)

Critical Step: Decolarizer

Front 10

Gram -ve bacteris is? and gram +ve bacteria ? (They stain what color?)

Back 10

- -ve: Red
- +ve: Purple/Violet

Front 11

Some bacteria does not stain well w/ Gram stain, what do you use to stain it and which are the species of bacteria that do not stain well?

Back 11

1. You use Acid Fast Stain
2. The bacteria that does not stain well is:
- Mycobacterium Tuberculosis
- Nocardia Spp.

Front 12

What are the three techniques of acid-fast staining?

How does Acid-Fast Bacteria Stain and NON-ACID fast bacteria stain?

Back 12

i.Ziehl-Neelsen Staining
ii. Kinyoun Staining
iii. Flurochrome Stain

Acid-Fast Bacteria: RED/PINK
NON Acid-Fast Bacteria: BLUE/GREEN

Front 13

What is the importance of Gram Stain in diagnosis and treatment?

Back 13

i. Determine the adequecy of the specimen for culture

ii. Make a presumptive etiological diagnosis and early clinical decision

iii. Suggest a need for non-routine labratory procedure

iv. Help make accurate interpretation of culture results

v. Provide a better insight into the current infection

Front 14

i. Do you need a flagella to be motile?

2. Is it essensial for bacterial survivial?

Back 14

1. NO

2. NO (It is NEVER present on cocci)

Front 15

Flagella is made up of three parts, what are they?

Back 15

i. Helical Filament:
-> Composed of protein [FLAGELLIN: hauch H antigen]
-> H+ means bacteria is motile and H- means they are immotile.

ii. Hook:
-> Short curved structure which anchors filament into the basal body

iii. Basal Body: Contains rod & 1 or 2 sets of double plates (rings). Located in cytoplasmic membrane & cell wall. (2 rings for gram +ve and 4 rings for gram -ve bacteria).

Front 16

In chemotaxis what is a +ve and a -ve response?

Back 16

+ve response: Organism swims from low to high [] of chemoattractants. [Up the concentration gradient]

-ve reponse: Organism swims from high to low [] of chemoattractants. [Down a concentration gradient]

Front 17

Other then flagella, the other appendages are composed of?

Back 17

- Pilin protein (also antigentic)

Front 18

Pilus/Pili are found only where?

What is the function?

Back 18

Gram -ve bacteria

Function: Sex Pilus/Fertility Pilus (F-Pilius) is used to transfer genetic material to gram via a process known as conjugation.

Front 19

What is Fimbriae:

Back 19

- Known as a common attachment Pili (Type 1 Pili). Predominantly found in Gram -ve but also in some Gram +ve bacteria.

Function: Adhesion of bacteria to surfaces. It helps bacteria establish colonization at a particular site.

Front 20

The Cell Envelop is composed of?

Back 20

- Outer Surface layer (Glycocalyx or S-Layer)
--> Also known as the slime or Capsule Layer
--> EPS (Polysacharaide);
--> NOT ALL bacteria possess a glycocalx.

- Cell Wall

- Cell membrane/Cytoplasmic Membrane

Front 21

What is the exception of having EPS glycocalx?

Back 21

Bacillus Anthracis (Causitive agent of anthrax) has a polypeptide instead of polysacharide.

Front 22

1. Define what SLIME layer is?
2. Define what a Capsule is?

Back 22

Both are part or form a part of the Glcocalyx:
i. Slime Layer - poor organization attachement to cell wall.
ii. Capsule - Organized structure, adheres to cell wall. Has K antigen (M - Streptococcus pyogenes, V1 for Salmonella Species).

Front 23

What is the function of the capsule?

Back 23

Adherence: attaches to the surfaces of other species members (colonies).

Front 24

What is EPS made from?

What are its functions?

Back 24

EPS - Glucose and Frucstose Polymers (Glucans and Fructans).

Functions:

-It has antigenic activity, thus it may be used for identification.

- Anti-Phagocytic Activity
- Prevention of Neutrophil Killing of Engulfed Bacteria
- Preventation of PMN Leukocytes
- Toxicity to host cell
- Protection: Protets anaerobes from oxygen toxicity, desiccation & nutrient loss

Front 25

What is the Quellung Reaction?

Back 25

Biochemical Reacion in which antibodies bind to a capsule of a bacteria (i.e. Strep. Pneemonia) and allow visualization. Positive test causes the capsule to become opaque and appears to enlarge.

Front 26

Which bacteria species DOES not have a cell wall?

Back 26

Mycoplasma Species.

Front 27

Describe the Cell Wall in Detail:

Back 27

Structure: Composed of Peptidoglycan (Also known as Mrein). A biological polymer UNIQUE to bacteria, containing both L- and D- amino acid isomers.

Glycan backbone is composed of a disaccharide of alternating NAM (N-acetylmuramic acid) and NAG (N-Acetylglucosamine) subunits linked by B-1,4 glycosidic bonds.

Each NAM unit has a bound Tetrapeptide (In most cases the terminal amino acid is D-alanine)

Front 28

The crosslinkage of tetrapeptide occurs where?

Back 28

i. Crosslinking occurs from 3rd amino acid of 1 tetrapeptide to 4th amino acid of 2nd tetrapeptide on NAM on adjacent Glycan backbone.

--> This provides rigidity and strenght and prevents osmotic lysis. <--

Front 29

What is the difference in the Peptidoglycan Structure in Gram -ve and Gram +ve bacteria (E.Coli)

Back 29

Gram -ve:
3rd Aa: Diaminopimelic Acid
Direct Lipoprotein Cross Linkage
Fewer Cross Linkages (<60%)
An open mesh framework

Grame +ve:
3rd Aa: L-lysine
Pentaglycine cross linkage
Greater Cross Linkage (>90%)
A tight framework

Front 30

Describe Gram Positive Bacterial Cell Wall.

Back 30

Gram +ve bacteria THIK peptidoglycan (50% - 60% of dry weight)
-> Teichoic Acids (Lipoteichoic Acid) (Acidic Anion polysacharides)

Function: Bind protons (maintain low pH), cations (Ca2+ & Mg2+)

Acts as ADHESINS, virus receptor sites
Additional CH2O and Proteins (depends on species)

Front 31

What are the roles of Lipoteichoic acid during disease.

Back 31

-Dermal Necrosis (Shwartzman Reaction)
- Induction of cell mitosis at site of infection
- Stimulate Specific Immunity
- Stimulate non-specific immunity
- Adhesion to human cell
- Complement activation
- Induction of (hypersensitivity anaphylaxes)

Front 32

Describe the Bacterial Gram Negative Cell Wall:

Back 32

- Complex morphology with a THINK layer of Peptidoglycan (5-10%).
- Membrane Contains PORINS (protein channels) that allow for specific nutrient transfer.
- Contain Lipopolysaccharide (LPS) which extends outwards.

Front 33

Describe Lipopolysaccharide Structure:

Back 33

There are three components:
i. Lipid A anchors LPS to outer membrane (TOXIC)
ii. Core polysaccharide portion
iii. Terminal Polysaccharide (repeating subunits [known as O-antigens] provides bacterial Serotypes - used for classification and identification (Known as the O antigen)

Entire structure is known as Endotoxin:

Front 34

Endotoxin Can Induce:

Back 34

- Fever
- Haemorrahagic necrosis
- Disseminated Intravascular Coagulation
- Production of TNF
- Activated Complement Pathway
- Stimulate bone marrow cell proliferation
- Enhance the immune & Limulus Lysate reaction.

Front 35

Which bacteria possess lipo-oligosaccharide instead of liopopolysacharide and what 2 components is it made of?

Back 35

Nesseria Sp.

It has:
i. Lipid A (Toxic)
ii. Core Oligosaccharide (external to lipid A)

Virulence Factor: LOS levels correlate with release of inflammatory cytokines (interleukin 1, interleukin 6, and tumor necrosis factor, alpha) important in the pathogenesis of meningococcemia and meningococcal meningitis.

Front 36

Compare and contrast Gram +ve/-ve cell walls:

i. Number of layers
ii. Chemical Make up
iii. Overall thickness
iv. Outer membrane
v. Periplasmic Space
vi. Porin Proteins
vii. Permeability

Back 36

i. +ve: 1 and -ve: 2
ii. +ve: Peptidoglycan, Teichoic Acid, Lipoteichoic Acid while -ve: Lipopolysaccharide, Lipoprotein, Peptidoglycan.

iii. Overall Thickness: +ve: Thick (20-80mm) and -ve: Think (8-11nm).

iv. Outer Membrane: +ve: No and -ve: Yes

v. Periplasmic Space: +ve: In some and in -ve: In all

vi. Porin: +ve: No and -ve: Yes

vii: Permeability: +ve: More Permeable -ve: Less Penetrable (permeable)

Front 37

What are the effects of Lysozyme:

<Define Spheroplast and Protoplast>

Back 37

Produced by humans in their saliva, mucus, blood, sweat and tears.

Action: Cleaves B-1,4 glycosidic bonds between NAM & NAG. Destroys ALL or PART of the cell wall:

Results In:
-> SPHEROPLAST: portion of the cell wall remains (mainly Gram -ve)
-> PROTOPLAST: cell wall completely removed (GRAM +ve more sensitive)

Front 38

What is the action of Penicillin:

Back 38

Action: Binds irreversibly to penicillin-binding proteins (PBPs). Tramspeptidase are enzymes required for peptidoglycan synthesis. Penecillin forms inactive complex with transpeptidase, inhibiting the formation of peptide cross-linkage, i.e. prevents complete cell wall formation. Results in defective cell wall walls with no protection to osmotic shock, leading to cell death.

Please Note: Penicillin ONLY acts on growing cells.

Front 39

What is the periplasmic space?

Back 39

Space between inner & outer membranes of gram -ve but is also present in some gram +ve. Gel Like area of loose network of peptidoglycan.

Contains nutrient transport proteins; nutrient acquisition enzymes (proteases);
detoxifying enzymes (B-lactamases); membrane derived oligosaccharides (MDO) and osmoprotectants.

Front 40

What is AXIAL Filaments:

Back 40

-Motile Bacteria that lack flagella
-Flagella-like filaments (protein chemically and structurally)
-Long think microfibril inserted into a hook
- Entire structure enclosed in periplasmic space (not exposed to external environment).
-It is also called Endoflagellum

Front 41

Describe Cytoplasmic Membrane:

Back 41

- A phospholipid bilayer 4-5 nm think: Phospholipid 30-40% & Protein 60-70%
- No Sterols EXCEPT Mycoplasma Spp
- Semi-permeable barrier

Front 42

Describe Cytoplasmic Membrane Structures:

Back 42

i. Active Transport
ii. Secretion of extracellular enzymes and toxins
iii. Oxidative phosphorylation
(bacteria does not have mitochondria)
iv. Biosynthesis and export cell wall components
v. Anchoring DNA (during cell division)
vi. Chemotactic Response

Front 43

Describe Ribosomes:

Back 43

RNA/PROTEIN bodies (60% RNA, 40% Proteins)
Sites of Protein Synthesis

-Bacterial 70S Ribosomes: large 50S + Small 30S
-Eukaryotic (80S)

Front 44

Describe:
1. Mesosomes
2. Chromatin Area (Exceptions!)
3. Plasmids
4. Inclusion Bodies

Back 44

1. Extensive invaginations of cytoplasmic membrane, mainly seen in Gram+ve.
2. Please Note Prokaryotes Possess:
-> NO distinc membrane to enclose nucleus
-> NO mitotic apparatus (Different from Eukaryotes)
-> DNA aggregated in one area known as a NUCLEOID

Bacterial Chromosome:
-> Single (haploid) circular DNA known as Chromatin BODY.

(Please note exceptions: Streptomycin and Borrelia sp contain Linear and Rhodobacter Sphaeroides (2 separate chromosomes)

ALL GENES are linked (NO HISTONES) Instead possess Mg 2+ and polyamines which act similarly to histones.

3. Circular extra-chromosomal DNA, smaller and separate from chromosome. Capable of self-replicating, carry supplemental genetic information (i.e. Antibiotic Resistance), Production of toxins, Mating Capabilites (F-Plasmid --> F-pilus)

vi. Inclusions Bodies - Storage Granules: Energy and Nutrient stores (seen under light microscope), Not permanent structures

Front 45

What is VEGETATIVE bacterial cell?

Back 45

- Bacteria capable of bacterial growth

Front 46

What are endospores?

Back 46

Endospores are NOT structure of bacterial cell wall. Specialized structures enable survival -- produced in environmental stress

Produced by: Bacillus and Clostridium Spp.
Resistant: UV, Irradiation, Chemical Disinfection, Drying
Require specialized stains (can see w/ light microscope).

Front 47

Describe Spore Structure:

Back 47

Coat: Keratin-Like protein provides an impermeable layer (resistance to antibacterials)
Cortex: Type of peptidoglycan (fewer cross-linking)
Spore Wall: Peptidoglycan layer (taken from cell wall of vegetative cell)
Core: contains complete nucleus, protein-synthesizing apparatus, energy-generating system (Glycolysis) and Calcium-Dipicolic acid (10% dry, weight, its characteristic).

Front 48

What is sporulation:

Back 48

A complex process that once started a vegetative cell committed to completing sporulation which take 6-8 hours.

Front 49

What is Germination:

Back 49

Outgrowth from Spore: 1 spore --> Vegetative cell.
Only occurs when environmental conditions are suitable for bacterial cell growth. Takes 2 hours to complete.

Front 50

What is Pathogenesis:
What is Virulance:

Back 50

Pathogenesis: Ability to cause a disease
Virulence: Degree of severity of disease.

Front 51

How do bacteria cause infection:

Back 51

-Enter the body and establishes itself.
-Free in body fluids or enclosed in cavity
--> Nutrition (Have to Eat, they may eat hosts food)
--> pH as they grow pH goes down
--> Toxic Wastes
Virulance Factor
- Structural (Adherence and/or attachments, Avoidance of Cell Attack)
- Nonstructural (Cause damage to host defense)

Replications (inter- or intra-cellular).

Front 52

Describe the Mycoplasmataceae Family:

Back 52

2 Genera: Mycoplasma Sp. and Ureaplasma Sp. with 4 human pathogenic species: M. pneumoniae (URT), M.genitalium & M. hominis and M. urealyticum (Genitourinary Infection)

They are smallest known free-living organism (0.15-0.3 um dia ~ poxvirus)

It has NO CELL WALL - classified as Mollicutes ("soft skin"). DO NOT synthesize peptidoglycan (Stain pink on gram stain - b/c no cell wall)

Contains Sterols in the Phospholipid bilayer. Sterols provide integrity & strength.

Cytoplasmic division lags behind genome replication, giving rise to filamentous shape.

Contains attachment organelles allowing attachment to epithelial cell lining in respiratory and urogenital tracts.

It has a small genome

Front 53

Mycoplasmataceae is susceptible to which drug?

Back 53

Amphotoricin B

Front 54

Mycoplasmataceae has a P1 adhesin, what is it used for?

Back 54

It attaches to receptors at base of cilia. Results in tissue destruction due to H2O2 and superoxide anions.

Front 55

What is a virus composed of?

Back 55

Covering: Capsid/Envelope

Central Core: Nucleic Acid (RNA or DNA) or Various Proteins (enzymes)

Front 56

What is the Capsid?

Back 56

It is found in all viruses and it protects the genome.

Sometimes refereed to as a nucleocapsid (Capsid + Nucleic Acid).

Composed of PROTOMERS (monomer unit) which organize into CAPSOMERS (polypeptides).

Advantage: reduced need for excessive genetic information and promotes self assembly (requiring no ATP or additional enzymes).

Front 57

What are the two types of CAPSID symmetry?

Back 57

Helical (appears ROD shaped) and

Icosahedral (SPHERE shaped)
-> General: 20 sided polygon (12 spaced corners) with two capsomers types:
-> Triangular Hexons.
-> Round Pentons.

Front 58

What is the CAPSID function?

Back 58

1. Provides the nucleic acid protection from digestion enzymes

2. Contains special sites on its surface, allowing attachment of the viron to a host cell.

3. Provides proteins that enable the virion to penetrate the host cell membrane
-> In some, to inject the infectious nucleic acid into the cell's cytoplasm.

Front 59

Describe the VIRAL envelope?

Back 59

-Does not surround the nucleocapsid of ALL viruses.

-UNIQUE protein-phospholipid layer
-> lipids from host cell membrane
-> Proteins are virus specific

Types of Envelope Proteins:
-> Matrix Proteins: link envelope to capsid (Stabilize Virus and mediates interaction between capsid proteins and envelope).

-> Surface Proteins: Exposed capsid proteins or envelope.
- Glycoproteins (sometimes referred to as Spikes or Peplomers)

They are required for the attachment of virus to host cell (Antigenic Determinants)

i.e. Hemaglutinin (surface glycoproteins) and Neuraminidase (surface spikes)

Front 60

Of enveloped and non-enveloped viruses, which ones are more sensitive to drugs?

Back 60

The enveloped viruses are more sensitive to drugs.

Front 61

The nucleoprotein core contains?

Back 61

The Viral Nucleic Acid (NA). It has either RNA or DNA (NOT BOTH).

It is VERY sensitive to chemicals and physical agents.

Front 62

What is a positive (+) stranded RNA virus? What is a negative (-) stranded RNA virus?

Back 62

1. (+) Strand RNA Virus: Genomes of same polarity as mRNA

2. (-) Strand RNA Virus: Genomes of opposite polarity to mRNA.

Front 63

What is the function of Nucleoproteins?

Back 63

It stabilizes Nucleic Acid during replication or have enzymatic function.

Front 64

What are the four types of Polymerases (synthesis of DNA and RNA)?

Back 64

- DNA-dependent RNA polymerase (poxvirus)
- RNA-dependent DNA polymerase (RNA tumor virus)
- RNA-dependent RNA polymerase (RNA viruses)
- Reverse Transcriptase (RNA to DNA) (HIV)

Front 65

Define the classification of viruses from Class I to Class IV.

Back 65

+Read pg 5-4+

Class I: Double-Stranded DNA
Class II: Single-Stranded (+) sense DNA
Class III: Double-Stranded RNA
Class IV: Single-Stranded (+) sense RNA
Class V: Single - Stranded (-) sense RNA
Class VI: Single-Stranded (+) sense RNA with DNA intermediate in life-cycle (Retrovirus)
Class VII: Double-Stranded DNA with RNA intermediate (i.e. HIV)

Front 66

Define some atypical virus like agents:

Back 66

Defective: complete viron but unable to replicate without helper virus

Pseudovirions: Contain host DNA not viral, infectious but no replications

Prions and Viroids : See later

Front 67

What are Prions?

Back 67

Subviral Particles: "Small Proteinceous infectious particles that resist inactivation by most procedures which modify nucleic acids"

i.e. Transmittable spongiform encephalopathies (mad cow disease).

Human: Neurodegenarative Creutzfeld-Jacob disease (CJD)

Front 68

What are Viroids?

Back 68

Infectious Agents/Subviral Particles
- Small, circular ss RNA, with/without capsid or envelope.

Mainly cause plant diseases (recently identified Hepatitis D as a viroid)

Front 69

What are Bacterial Viruses?

Back 69

They are also known as PHAGE, is a viral agent of bacteria.

Complex Structure:
-> Phage Head: protein capsid (icosahedral symmetry) which surrounds Nucleic acid (Majority ds DNA)

-> Tail: attached protein (helical in structure), which may have base (end) plate with spikes (PINS) and tail fibers, which allows injection of nucleic acid in bacterial cell.

Front 70

What are the Definitive Properties of Viruses ?

Back 70

- Genome directs synthesis of viron components within an appropriate host cell
- Progeny virus particles produced by assembly of newly made virus components
- Progeny virus particles spread infection to new cells.

Front 71

What are the physical and chemical requirements for bacterial growth?

Back 71

Physical: Temperture, Osmotic Pressure, pH.

Chemical: Carbon, Nitrogen, Sulful, Phosphorus, Trace Elements, Oxygen, Organic Growth Factors.

Front 72

What is the requirement for bacterial growth?

Back 72

1.There must be continuous macro-molecular synthesis and genome replication.

2. Bacterial cell uses Binary Fission

3. The time required to divide is known as doubling time.

Front 73

What is the doubling time for E.Coli?

Back 73

20 minutes.

Front 74

In a closed system (finite nutrients and space and no removal of waste) What is the Lag, Log, Stationary and Death Phases?

Back 74

Lag Phase: no cell division, need adjustment to new environment.

Log Phase: Cell adjustment is complete, Metabolism and Replication at full speed.

Stationary Phase: Rate of cell death = the rate of multiplication.
- > Nutrient depletion, pH changes, accumulation of waste and reduced oxygen (can induce endospores).

Death: decline in growth rate, (reversal of log phase). Death in geometric proportions, Depletion of nutrients/O2/too much waste .

Front 75

How do you measure viable bacteria?

Back 75

- Serial Dilutions (read on page 6/7-5)
- Plate Count
- Filtration
- Turbidity

Front 76

Define the 3 temperatures which control bacterial growth.

Back 76

MINIMUM: Lowest temperture permitting bacterial growth.

MAXIMUM: Highest temperature permitting bacterial growth.

OPTIMUM: A narrow range of temperature that promotes the fastest growth.

Front 77

What are the Psychrophile/Mesophile and Thermophiles?

Back 77

Psychrophiles: Psychrphilic Bacteria Capable of growing at ~4 C.

Mesophile: Opt Temp: 20-40.
- Capable of Growth 10-50C.
- Group containing Human Pathogens (30-37C).
- Example E.Coli.

Thermophile:
Opt Temp. 60C. Capable of Growth in 45-85C. Incapable of Growth at usual body temperature (not involved in Human Infections).

Front 78

What about water and bacterial growth?

Back 78

All bacteria require water for growth and reproduction.

Aw = index of free available water = atmospheric pressure.

RH = 1.0 Aw. Therefore, 90% RH = 0.90 Aw.

Most Bacteria have active metabolism at Aw > 0.9. Below Aw 0.9 Bacteria is unable to grow.

EXCEPTIONS:
Xerotolerant: lower Aw.
Fungi able to grow at Aw 0.6
Salt-Tolerant Bacteria - Halophiles (High [Solute], low Aw)

Front 79

1. Oxygen is considered?
2. Microbes convert toxic products to molecular oxygen by?

Back 79

1. Limited factor in bacterial growth.
2. (a) Catalase
(b) Peroxidase
(c) Superoxide Dismutase

Front 80

What are?
(1) Obligate Aerobes?
(2) Microaerophiles
(3) Obligate Anaerobes
(4) Facultative Anarobes

Back 80

(1) Totally dependent on oxygen

(2) Grow in presence of O2 BUT tolerate only up to 4% of oxygen.

(3) Grow ONLY in the absence of oxygen.

(4) Can grow in the presence and absence of oxygen.

Front 81

Which of these microorganisms have Catalase and/or Superoxide Dismutase to protect against toxic forms of oxygen.

(a) Aerobe
(b) Facultative Anaerobe
(c) Microaerophile
(d) Obligate Anaerobe

Back 81

(a) Has Both
(b) Has Both
(c) Just Superoxide Dismutase
(d) None

Front 82

1. What is the CHNOPS micronutrient broth?

2. What are the Minerals ?

3. What are the trace elements?

Back 82

1. Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulpher.

2. K+, Ca2+, Mg2+, Fe2+/Fe3+

3. Mn, Zn, Co, Ni, Cu, Mo

These trace elemtns are components of various enzymes and/or are cofactors of some enzymes.

Front 83

Classify the bacteria based on Source of Energy Utilization:

(i) Autotrophs
(ii) Heterotrophs
(iii) Phototrophs
(iv) Chemotrophs
(v) Lithotrophs
(vi) Organotrophs

Back 83

Autotrophs - Utalize inorganic Carbon (CO2) as a sole/principle source of Carbon.

Heterotrophs - Require reduced or pre-formed Organic molecule produced by other microorganisms

Phototrophs - Energy is derived from sun light and NOT directly from any organic or inorganic source

Chemotrophs: Oxidation of organic or inorganic macromolecules

Front 84

How do you cultivate Fungus?

Back 84

Sabouraud's Agar (made from simple peptone) and agar. pH adjusted to 5.6.

Front 85

What are the current methods of Fungul Identification?

Back 85

-Gene Sequencing of 26S rRNA
-Internal Transcript Spacer 1 and 2 regions. These contain conserved regions useful for the design of unversal primers that amplify the gene from all pathogenic and nonpathogenic fungi using PCR.

Front 86

Describe the stages of viral Multiplication:

Back 86

(i) Adsorbption (attachment)
(ii) Penetration (Entery)
(iii) Un-Coating
(iv) Replication of Macromolecules (DNA, RNA and Proteins)
(V) Assembly of virus from the host
(VI) Release of mature virus from the host.

Front 87

How do viruses enter the cell?

Back 87

(i) Membrane-Envelope Fusion
(ii) Receptor-Mediated Endocytosis

Front 88

What is a permissive cell vs. susceptible cell?

Back 88

Susceptible Cell - cell that can allows the virus to enter.

Permissive cell - lets the virus replicate.

A cell can be permissive but not susceptible.

Front 89

Describe Viral Budding (Egress)?

Back 89

1. Viral Peplomers are arranged thought the cell membrane.

2. Matrix proteins arrange along side the modified cell membrane
3. The nucleocapsid now moves towards the matrix protein concentrated area and the whole complex starts to buds out from the cell.

4. Newly mature virus is released from the host infected cell.

Front 90

What are transformed cells?

Back 90

When viral DNA integrates into the cellular DNA. Cellular morphology, physiology and behavior changes. These 'altered' cells are called transformed cells and they have a potential to cause tumors in small animals.

Front 91

What is the difference between an eclipse phase and a latent phase?

Back 91

Eclipse phase - when the infectious viral particle cannot be seen or recovered from infected cells. This phase ends when the first virus particle is observed inside the infected cell.

Latent Phase: The progeny accumulated inside the infected cell ready to be released into the medium. This phase ends when first free virus is released.

Front 92

The aims of using antimicrobial agents are?

Back 92

i. Reduce microbial #s
ii. Slow down or Inhibit Microbial Growth
iii. Kill/Eliminate microorganisms.

Front 93

Define:
i. Disinfection
ii. Antisepsis
iii. Sterilization
iv. Germicidal
v. Decontamination
vi. Biocide
vii. Tolerance

Back 93

i. Destruction/Removal of vegitative pathogen from surface.
ii. Killing or inhibiting of microbial grows on living tissues
iii. Removal or Killing of ALL living microorganisms (Absolute Term, can't have a partially steralized surface).
iv. Able to kill or inhibit growth and is sufficiently nontoxic to be used on living tissues.
v. Reduction in microbial numbers so that object is now safe to handle.
vi. General term: Refers to chemical or physical agents with wide spectrum of activity against microorganisms.
vii. Decreased effect of a biocide or anti-infective agent against a target microorganim.

Front 94

Define:
i. STATIC
ii. CIDAL
iii. LYTIC

Back 94

i. Inhibit (i.e. FungiSTATIC - inhibit growth).
ii. Kill (i.e. Bacteriacidal = kill bacteria)
iii. Lyse (i.e. Bacterialytic = lyses bacteria).

Front 95

What is the MOST resistance organisms and the LEAST resistant organism?

Back 95

MOST: Prions
LEAST: Enveloped Viruses

Front 96

What is a common method of physical control?

Back 96

i. HEAT

Front 97

Heat as a disinfective does what?

Back 97

Denature & Coagulates microbial proteins, breaks hydrogen bonds --> inactivation of enzymes --> Organisms are killed.

Front 98

Which one is better wet or dry heat?

Back 98

Wet/Moist heat is better then dry heat. Also increasing pressure will speed up the killing time. AUTOCLAVE = large pressure cooker.

Front 99

What is Ethylene Oxide Gas?

Back 99

Alkylaing agent, react with guanine of DNA and functional protein groups.

Use this on heat sensitive material, plastics, complex devices and equipment.

Front 100

What are some other forms of disinfection?

Back 100

Radiation, Filtration and Cold.
(see 9/3 for more information).

Front 101

What are the mechanisms of actions of chemical agents?

Back 101

1. Reactions that affect proteins. Denatruation, hydrogen and disulfide bond disruption.

Can be temporary or permenenatl.

Types of reactions that affect proteins:
- Hydrolysis
- Oxidation
- Attachment of atoms or chemical groups.

2. Reactions that affect membranes
3. Reactions that affect other cell componenets.

Front 102

Can disinfectants act as antiseptics?

Back 102

Yes. Increase the concentration.

Some can be too dangerous to use as antiseptics.

Front 103

Distinguish between high, low, and mid level of disinfectants.

Back 103

High: Viruses, Fungi, Mycobacteria and bacterial spores inactivated

Mid: Viruses, Fungi, Microbacteria inactivated

Low: non-sporulating bacteria and lipid-enveloped viruses inactivated.

Front 104

What are the desirable proporties of antiseptics?

Back 104

Can be incorporated into many things such as soaps.

- Wide Spectrum
- Rapid Activity
- Low level of damage, irritation or toxicity to the tissue being treated.
- Some form of persistance, following use.

Example of use:
i. Skin Hygine
ii. Reduction in the numbers of microorganisms on a mucous membrane or the skin before breathing it.
iii. Treatment of skin or wound infection.

Front 105

What is selective toxicity?

Back 105

compounds with minimal or no effect on host cells but maximum effect against the infecting microorganisms.

IDEAL:
-> targets UNIQUE to the infecting organisms
-> Peptidoglycan
-> Reverse Transcriptase
-> Ergosterol

Alternativly, targets should be very different from the host cell (maybe specific binding site).

Front 106

Quickly describe antivirals?

Back 106

Antivirals: 60% of infectious diseases are caused by viruses. Viruses tend to be singiicantly narrower in spectrum then antibiotics.

Front 107

What are some of the challanges in developing new antivirals?

Back 107

1. iruses are obligate intracellular parasites
2. When symptoms become obvious: virus already completed replication cycle.
3.Virus uses normal cell enzymes or enzymes similar to host enzymes.

Front 108

Define some of the targets that antivirals go for (on the virus)?

Back 108

- Attachment: preventing the attachment, subsequent stages of viral infection and replication are inhibited.
- Entry: blocking viral penetration into the host cell and / or viral uncoating, subsequent
- Viral Release: Prevents the virus from being released from the host cell (i.e. Neuroamidase Inhibitors)
- Genome Replication: Selectivly inhibit and interfere with the processes necessary for replication of the viral genome. (i.e. Inhibition of enzymes such as reverse transcriptase).

Front 109

Define NRTI and NNRTI? What about Protease Inhibitors?

Back 109

NRTI (nucleioside reverse transcriptase inhibitors) such as AZT.

-> Inhibit function of viral DNA polymerase (Acyclovir HHV I and II). They are nucleoside analogue and disrupt the reverse transcriptase, for HIV it is AZT.

Selective because they undergo a biotransformation only when virus is present because they use Viral Thymidine-Kinase Phosphorylation.

(Nucleoside Analogue)->Monophosphate->Diphosphate->Triphosphate

The triphosphate form inhibits:
- Viral polymerase
- Chain Elongation prevented/Terminated
-Errors in Replication
- Depletion of levels of essential compounds, e.g. Guanine.

NNRTI:
Bind to and sterically block sites on RT enzymes

Protease Inhibitors: Block Enzymatic cleavage of viral polyprotein.

New anti-retroviral compound: Enfuvirtide (Fuzion): blocks fusion of HIV viral envelope and host cell membrane.

Front 110

What are some mechanisms of viral resistance to antivirals?

Back 110

Variety of mechanisms: e.g. mutation in TK genes.
Emergence of resistant strains influenced by:
- Viral Replication
- Higher rate of replication = higher rate of spontaneous mutation
- Rate of mutation
-> ssRNA viruses have more mutations that dsDNA viruses.
- Rate of mutation differs in viral genes. (i.e. no resistance to acyclovir found yet).

Front 111

What is the patient group that would require anti-fungal therapy?

Back 111

- Immunocompramised / Immunosupressed individuals (i.e. AIDS patients), people on corticosteroids.

Front 112

What are some of the challenges with treating fungal infections?

Back 112

1. Fungi are slow growing, chronic infections.
2. Fungal and host cells are both eukaryotic, so it is hard to find a compound with good selectivity -> limited useful anti-fungal.

Front 113

Describe the action of Polyenes (i.e. Amphotericin B)?

Back 113

-> Typical antifungal
-> Bind directly to ergosterol (sterol) membrane, creating a pore. Membrane becomes more permeable causing cytoplasmic contents to leak out.
-> Has a lot of side-effects

Front 114

In anti-fungal treatment what are some of the Nucleic Acid Synthesis Inhibitors?

Back 114

-> Only, its name is 5-flurocytosine.
-> Gets converted to 5-Flurourecil by fungal cytosine deaminase.
-> Inhibits synthesis of DNA, RNA and proteins.

Front 115

Define the Azols (anti-fungal)?

Back 115

->Inhibit P450 Cytochrome enzyme (Ianosterol 14-alpha-demethylase)
->blocks Inasterol to Egrosterol production
-> Changes the composition of membrane
->250X more effective on fungal then mammalian membrane.

Front 116

What do the Allamines do (anti-fungal
)?

Back 116

-Inhibit the enzyme (Squalene Epixidase) .
- Involved in the conversion of squaline to Ianosterol.
- Accumulation of squaline increases membrane permeability.

Front 117

Describe the effects of Echinocandins?

Back 117

-Anti-fungal
-Blocks (1,3)-Beta-D-Glucan Synthase.
-Target Cell Wall

Front 118

What are some of the ways that the fungas can develop resistance to antifungals?

Back 118

- Mutation in key enzymes
- Decreased rate of transport into fungal cell
- Alternation of target enzyme
- Alternation of Ergosterol Biosythesis Pathway
- Growth as a biofilm

Front 119

Describe the Basic principles of antibiotic Therapy?

Back 119

-> Most natural or synthetic antibiotics usually target either a bacterial: Structure or Physiological Function

Nomenclature:
- Chemical Name
- Generic Name *
- Trade Name

Front 120

What are some of the targets of antibioitcs?

Back 120

1. Inhibitors of protein synthesis
2. Inhibitors of nucleic acid synthesis
3. Inhibitors of metabolism
4. Inhibitors of cell membrane functions
5. Inhibitors of cell wall formation

Front 121

Describe B-lactam antibiotics?

Back 121

Large family of cell wall inhibiting compounds. All contain the B-lactam ring.
--> Penicillins: B-lactam ring + 5 membered thiazolidine ring
-->Cephalosporins: B-lactam ring + 6 membered dihydrothiazine ring.

Active only on growing cells

Beta Lactam ring forms the basic structure

Inhibit the transpeptidation reaction (Enzyme is a PBP) involved in cross-linking of peptidoglycan subunits into growing cell wall.

Front 122

What is the mechanism of b-lactam antibiotics?

Back 122

Penecillin Enters the Bacterial Cell -> Target: Penicillin Binding Protein (PBP) -> Blocks transpeptidation -> Cell wall not properly cross linked -> Cytoplasmic Contents continue to be produced -> Bacterial Cell Eventually Bursts (CIDAL effect)

Front 123

What are some mechanisms of Bacterial Resistance?

Back 123

1. Decreased Permeability to the drug (Decrease/block uptake, or multi-drug resistance pumps)
2. Alternation of target (Change in receptor site affinity, Modification of metabolic pathway).
3. Enzymatic Inactivation (B-lactamases, Chloramphenicol Actetyltransferases).

Antibiotic Resistant Bacteria = bacteria that are not inhibited or killed at concentration of the drug achievable after normal dosage.

+look at chart on 11/1+

Front 124

Describe the mechanism of hydrolytic enzymes that affect resistance. Using B-lactamases as an example:

Back 124

B-lactamases:
Common mechanism of resistance to B-lactam antibiotics = production of inactivating enzymes called B-lactamases. Can be subdivided into:
-> Penicillinases: Inactivate Penecillin antibiotics
-> Cephlasporinases: Inactivate Cephalosporin antibiotics.

Hydrolytic Enzyme: Cleave B-Lactam ring -> inactivated antibiotic.

TEM-1 and 2 B-lactamases are most common. (increased problem clinically).

Front 125

Describe the common clinical microbiology labratory tests for determining bacterial antibiotic susceptibility/resistance.

Back 125

1. Kirbey-Bauer Test ("Disk Diffusion") test.

- Fully standardized assay
- minimizes selection for resistance
-Bacterially-seeded Muller Hinton agar plates + discs of different antibiotics (specific concentration).

Prinicple: As distance from the disc increases, concentration of antibiotic in the agar decreases. (A large zone of inhibition means that you do not need high dose of drug to kill the microorganism, so it is susceptible.

Inhibition zones are compared to a standardized table, showing zones of inhibition for a known species.

Modification of this assay: Breakpoint Testing

2. Broth Dilution Method

- Dilutions of antibiotics are made in liquid growth medium (Muller-Hinton Broth) -> innaculated with clinical isolates and incubated.

Looking for:
MIC = Minimum Inhibitory Concentration. Provides a quantitative result of the relative susceptibility of a clinical isolate.

Front 126

Why would you carry out an MIC test?

Back 126

a. Patient is critically ill with a potentially fatal infection such as meningitis or endocarditis.
b. Monitoring of resistance development during therapy
c. Low level of antibiotic resistance possible in the clinical isolate
d. Determine activity of a new antimicrobial in vivo.

3. E-Test Strips = Alternative to tube/microtiter plate of MICs

- Polymer strip with gradient of antibiotic concentrations
-Place onto plate inoculated wtih clinical isolate.
MIC = where zone of inhibition meets the strip.

Front 127

How would you carry out a MBC (Minimum Bacteriocidal Concentration)

Back 127

Place samples from MIC tubes w/ no visible growth onto agar plates & incubate. MBC = antibiotic concentration at with NO GROWTH occurs on agar plate. Compare MIC which means NO VISIBLE GROWTH.

Front 128

What are some factors influencing the the outcome of antibiotic treatment?

Back 128

1. Type and site of infection
2. Condition of patient
3. Pharmacological Proporties of the drug

Front 129

What is recombination?

Back 129

Breaking and rejoining of DNA in new combinations. Newly incorporated DNA must be stably mainted (incorporated into the chromosome). Achived via recombination:
- Homologus (General)
- Non-Homologus (Site Specific): "Cut and Paste".

Front 130

What is Conjugation?

Back 130

Transfer of DNA via plasmids... another way bacteria can aquire resistance.

=> mostly observed in gram-negative bacteria.

Conjugation Requires production of pilus:
-> Encoded for by F-Factor (a plasmid)
-> Encodes for tra genes (transfer) & genes for pilus production.

Cells are defined as F+ (having the F-factor) or F-(lack plasmid).

1. F+ cell produces conjugative pilus -> (binds F+ and F- cells).
2. Donor cell (F+) plasmid DNA ncked and becomes two strands.
3. Strand in Donor Cell is duplicated to reform plasmid.
4. Second Strand Enters recipient (F- Cell).
5. Strand in recipient is duplicated to form complete plasmid.
6. Recipient is now transformed and becomes F+.

Front 131

What are the possible outcomes during

Back 131

1. Complete Transfer From Donor = Recipient Becomes F+ Cell
2. Incomplete Transfer From Donor = Recipient Cell Remains F-.
3. Complete transfer to recipient and integration into chromosome = Recipient is Hfr cell (High Frequency Recombination).
4. Intergrated F plasmid initiates transfer from Hfr Cell to new F- cell = Transfer of F plasmid plus some or all of the attached bacterial chromosome to the new cell.

Front 132

What is transformation?

Back 132

It is the aquasition of exogenous DNA. Source: broken/dead bacterial cell.

=> can be discriminatory or indiscriminatory ==> based on "passwords"

Uptake of DNA: by DNA binding proteins present on cell wall.
- not all bacteria are/can become competent.
-Competency dfferent at different stages in growth cycle.
-Can be turned on and off in response to signaling molecules.

Front 133

Describe Transduction:

Back 133

Phage Types
1. Virulent (lytic)
After phage replication: death of infected bacterium (lysis) -> phage released.
2.Temperate
Able to switch between virulent /lytic phase (1) and state where phage DNA is stably integrated within host bacterial DNA: "prophage."
-> Bacterium Has Undergone Lysogeny
-> Phage gene expression normally repressed.
---> Expression & Replication can be triggered by stress (i.e. pH change, iron levels, etc.)

Front 134

Describe Generalized Production:

Back 134

1. Generalized:
1. Phage attaches to bacteria
2. Injects DNA
3. Bacterial chromosome breaks up Phage DNA produced.
4. Production of phage heads & Tails
5. Cell Lysis; new phage is released
6. Can produce a DEFECTIVE Phage: Bacterial DNA instead of phage
6i. Phage attached and injects DNA
6ii. Introduced DNA incorporated into the chromosome / NO NEW PHAGE IS PRODUCED

Front 135

Describe Specialized Transduction:

Back 135

1. Phage attached to bacteria.
2. Injects DNA
3. Phage integrates into the chromosome
4. <- Maintains stable relationship, Switches into lytic mode-->
5. Phage and Bacterial DNA mixes.
6. Defective Phage Hybrid: part bacterial, parge phage DNA
7. Phage attaches and injects DNA
8. Introduced DNA incorporated into chromosome (No New Phage Products)

* Major difference between specialized / generalized transduction is that in specialized transduction, the DNA is a mix *

Front 136

What are transposition?

Back 136

Transposons (Tn) = "jumping genes"

They jump between chromosomoes or within the chromosome using:
- Non-Homologus Recombination
- Non-Specific Recombinases (The Transposase Enzyme)
- Transposon may then be transferred to other bacteria via mechanisms discussed.

Front 137

Pathogenicity is a multi-factorial event. What does that mean?

Back 137

1. Involves both host and microbial factors.

Front 138

Dissemination requires that a organism can overcome:

Back 138

1. Physical Barriers
2. Immune Barriers

Front 139

Why study microbial pathogenesis?

Back 139

1. Deelopment of new antiviral treatment and antimicrobial treatment
2. Anti-Infectives
3. Anti-Adhesives
4. Anti-toxins
5. Vaccines

Front 140

What are ther various reservoirs containing microorganisms?

Back 140

1. Humans - Endogenous/Exogenous
2. Animals - Various/Cows/Dogs
3. Insects - Lice/Ticks
4. Enviornment - Aquatic/Terrestrial

Front 141

Does exposure always result in a disease?

Back 141

No! it does not always results in infection/disease, but it can. Here are the possible outcomes:
1. Infection & Damage
2. Establishment of a permanent relationship
a. Commensals
b. Persistent/Latent Infection
3. Inapparent/Subclinical Infection
4. Prevention of infection or complete clearence of pathogen.

Front 142

What factors influence the outcome of exposure to a certain disease?

Back 142

- Microorganism's abiliy to breach host defense / barriers and evade destruction.
- Microorganism's tactics for replication, spread, establishment of infecton and causation of disease.
- Body's innate and adaptive immunologic ability to control and eliminate the invading microorganisms.
-Microorganisms's ability to transmit itself to a new susceptible host

Front 143

What are the key stages in the pathogenic process?

Back 143

1. Exposure and Entery into the host
2. Attachment
3. Invasion
4. Effects on the host
5. Evasion of the immune response
5. Dissemination

Front 144

Describe the different pathogenic entery routes:

Back 144

Respiratory tract: Droplet Inhalation
Gastrointestinal Tract: Ingestion
Genitourinal tract: Sexual contact/Activity
Eyes: Injury /Abrasion and Enviornmental
Skin: Cuts/Abrasions and Inoculation

Front 145

What factors can increase the likelihood of microbial entery?

Back 145

1.Damage to the host epithelium.
2. Presence of a foreign body
3. Disruption of normal microflora due to antibiotic therapy
4. Damaged/Deficient immune defenses
5. Drug or Radiation supression of the immune system
6. Transfer of bacteria to unusual sites.

Front 146

Describe attachment?

Back 146

Attachment: physicial attachment of the microorganism to the cell surface.

- Necessery in order to colonoize a particular site or infect a certain cell.
- Ability to attach depends on interaction between host cell receptors and microbial surface components (adhesins:ligands).
- Colonization at specific site is defined by the following:
-> Ability to adhere
-> Favourable Enviornment (pH, nutrients, etC).
-> Presence/Absence of normal microflora/commensals

Receptors for attachment can be
-> Specialized protein (usually limited distrubution)
-> Component of cellular membrane, e.g. phospholipids
-> Surface components e.g. glycoproteins
-> General surface receptors, e.g. Hormones.

Some viruses can use multiple receptors (increases range of susceptible cell types).

Adhisins:
Pili & Fimbriae (bacteria)
Expression may be coordinated along with other virulence factors.
e.g. cholera toxin and TcpA (Toxin Co regulated Pilus A).
Often expressed as required in response to favourable enviornment.

Example in E.Coli:
Ligand: Fimbrial Protein
Receptor: Galactose Disaccharide of Glycolipids.

Afimbrial Attachments: Ligans can be any cell structure: Capsule, Cell Wall, Flagella, Lipoteichoic Acid., etc.

Front 147

What is the adhesion receptor / ligand for H. Influenzae?

Back 147

Ligand: Outer membrane protein P2
Receptor: Sialic acid-containing oligosaccharides of mucin.

Front 148

How do viruses use Capsids to interact ?

Back 148

Rhinoviruses: Canyon/Cleft on surface of Rhinovirus (non-enveloped) interact with Host cell receptor = Intercellular Adhesion Molecule - 1 (ICAM-1).

ICAM-1 Charachteristics:
-> Integral Membrane Protein
-> Member of Ig Superfamily
-> Present on surface of many tissue types, including nasal epithilium
-> Normally binds to Lymphocyte Function-Associated Antigen (LFA-1)

Other viruses use projecting surface structures or components of the viral envelope (Fusion proteins, Haemaglutining, etc) for attachment.

Front 149

Describe Invasion (bacterial)

* Key * VIRUSES must enter the cell / inasion.

Back 149

Bacterial Entery Mechanisms:

Phagocytic Cells: Entry via phagocytosis

Non-Phagocytic Cells: Variety of possible mechanisms:
-> Invasins: Bacterial surface proteins that interact with specific receptors -> induce endocytosis.
->Host Cell Cytoskeleton Rearrangments: Usually triggered by injection of bacterial proteins into host cell>Membrane Ruffling.

END RESULT: regardless of mechanism/type of cell: bacterium located in membrane-bound vacule. Subsequent adaptations now necessary to evade lytic enzymes, etc.

Front 150

How does the virus enter the cell?

Back 150

Can be different depending on the virus:
-> Separate envelope glycoproteins for receptor binding (attachment) and subsequent membrane fusion
-> OR single viral proteins can carry out both functions.

* Some need a change in pH to enable genome entry into the host *

Front 151

What are the three types of mechanisms that the virus uses to enter the cell?

Back 151

Nonenveloped Translocation:
i. Virus bind to surface receptor
ii. Virus enters VIA receptor mediated endocytosis (REM)
iii. Acidification causes capsid change, viral genome is released.

Enveloped Receptor mediated Endocitysis:
i. Virus Binds to surface receptor
ii. Virus enters VIA REM
iii. Membrane fusion, Nucleocapsid/Genome is released.

Enveloped membrane fusion:
i. Virus binds to surface receptor
ii. Virus & Host cell membrane fuse
iii. Membrane fusions / Nucleocapsid/Genome released

Front 152

What happens if you have an Inapprarent/Subclinical infection?

Back 152

Colonization by pathogen but there are NO symptoms of disease.

Organism is kept in check/controlled by host immune defenses. Level of microbial replication is not sufficient to result in overt symptoms.

Why does the infection not become clinically obvious?
-> Infected tissue is undamaged
-> Infection is controlled before organisms reaches its target tissue
-> Target tissue is expendable
-> Damaged tissue is rapidly repaired
-> Extent of damage is below a function threshold.

Front 153

What happens when the outcome is a chronic infection?

Back 153

Microorganism continually is at detectable/shed at low levels.

The infection may be mild or may have no clinical symptoms:
-> i.e. Hepatitis / Typhoid Fever

Front 154

What happens when the infection is Latent infection? i.e. the outcome of infection.

Back 154

Virus NOT continually detectable. There is intermitten reactivation -> microorganism is detactable / shed again... but in phases. (i.e. Genital herpes/ Tuberculosis).

Front 155

What happens for a slow virus infection? SSPE

Back 155

SSPE = subacute Sclerosing Pan Encephalities.

Chronic persistent measles virus infection of the CNS.
-> Can occur 2-10 years post-measles infection
-> Progressive neurological degeneration due to brain infalmmation and tissue damage.

Front 156

What happens for a slow virus infection? SSPE

Back 156

SSPE = subacute Sclerosing Pan Encephalities.

Chronic persistent measles virus infection of the CNS.
-> Can occur 2-10 years post-measles infection
-> Progressive neurological degeneration due to brain infalmmation and tissue damage.

Front 157

What happens for a slow virus infection? SSPE

Back 157

SSPE = subacute Sclerosing Pan Encephalities.

Chronic persistent measles virus infection of the CNS.
-> Can occur 2-10 years post-measles infection
-> Progressive neurological degeneration due to brain infalmmation and tissue damage.

Front 158

What happens for a slow virus infection? SSPE

Back 158

SSPE = subacute Sclerosing Pan Encephalities.

Chronic persistent measles virus infection of the CNS.
-> Can occur 2-10 years post-measles infection
-> Progressive neurological degeneration due to brain infalmmation and tissue damage.

Front 159

What is virally induced transformation?

Back 159

Transformation of host cells = first stem in process of cancer/tumor formation.

i. Mechanism of transformation: activation of cellular proto-oncogenes. (i.e. HLTV-1 retrovirus, causes adult acute T-lymphocyte leukemia)

Virus injects chromosomes into host cell chromosome --> activation of cellular proto-oncogenes. (Either cis/trans).
-> inserted virus introduces promoter and enhancer sequence that can alter normal gene expression.

Why does altering the control of genes expression have this effect?
-> over-expression
-> inappropriate expression
-> Produced in wrong type of cell
-> Function of the proteins is different.

Front 160

What is the mechanism of transformation: Viral proteins / DNA viruses (all viruses except Parvoviruses)

Back 160

Action:
-> Viral Proteins: ("transforming proteins" act on specific cellular proteins => normal viral proteins involved in viral replication.

Virus:
Polyomavirus - Large T antigen, Small t antigen target p53, and pRb

HPV - E6/E7 target p53 and pRb.

Cellular targets for viral proteins: Tumor Supressor Proteins (TSPs), which are involved control of the cell cycle. If their function is blocked -> repeated cell cycles.

Outcome: uncontrolled cell growth.

TSPs target:

Rb Genes: normal role is to prevent the cell from entering the S phase

p53 gene: Normal role: acts as a transcription factor and regulates:
-> synthesis of a protein that inhibits certain cell kinases.
-> DNA proof reading

Front 161

How does the outcome of tissue damage/cell damage present?

Back 161

Development of recognizable symptoms is usually link to damaged/destructed cells.

Can occur:
- Directly
- Due to immune response (immunopathology) = damage to host cells as a result of the microbially-induced immuno response.

Front 162

What does the B-(1,3) glucan component of P. Brasiliensis triggers?

Back 162

Inflammatory response which is linked to virulence.

Front 163

Describe antibody-mediared immunopathology?

Back 163

i. Immune Complex Diseases
-> Excessive microbial antigen circulated as a complex in body
-> Not cleared by RES
-> Deposited in tissues, capillaries, glomerular basement membrane , etc.
-> Complement activation and inflammation.

ii. Enhancement of Infectivity
Antibodis specific for the virus enhance its entery into macrophages by interacting with Fc and/or complement receptors.
-> Suggested role in dengue haemorrhagic fever or dengue shock
-> Problematic when it comes to vaccine development.

Front 164

Describe T-Cell mediated Immunopathology?

Back 164

Damage occurs as a result of cytolysis of infected cell or through cytokine release.

May be linked to delayed type-hypersensitivity (CD4+ mediated) response.

Associated cell damage is due to release of:
-> Proteolytic enzymes
-> Reactive Radicals, e.g. peroxide
-> Cytokines, e.g. TNF-alpha

Front 165

Explain the primary mechanisms by which viral replication and infection damages a host cell or interferes with its normal function?

Back 165

1. Cytolytic Effect of viral replication
2. Degradative Enzymes
3. Toxic Structures
4. Physical Growth through tissues
5. Toxins.

Front 166

How does a virus achieve host cell death and or lysis?

Back 166

1. Prevention of cellular growth and repair which is achieved by:
-> Viral inhibition of synthesis of cellular macromolecules
-> Viral production of degradative enzymes and toxic proteins

2. Active or passive blocking of cellular protein synthesis.

3. Viral Replication & Build-up of viral components and progeny interferes with structure and function of cell or disrupts lysosomes - > cell lysis (autolysis).

4. Expression of viral antigens and disruption of cytoskeleton can affect cell-to-cell interactions and can change cell appearance ( increases susceptibility to immune-mediated cytolysis).

5. Virally infected cell expresses viral glycoproteins on its surface.

6. Induction of apaptosis (by viral infection or immune response).
++ Advantage to virus: enables viral release
++ Disadvantage to virus: limits amount of virus produced.

Front 167

How does the virus alter the way the cell looks / appearance?

Back 167

Some viral infection can change the appearance and properties of the target cells causing cytopathic effects:
-> Inclusion Bodies
->Cell Rounding
->Vacuolization
->Formation of giant multi-nucleated cells

Front 168

Why do these Cytopathic Effects (CPEs) occur during viral infection?

Back 168

Virus changes cell structure, e.g. membrane, chromosome.

Virus causes changes in host cell membrane -> Fusion with neighboring cells

Front 169

What are some of the degradative enzymes viruses release?

Back 169

Enzyme:
i. Hyaluronidase - Breaks down hyaluronic acid of connective tissue.
ii. Streptokinase - Breajs down fibrin clots (converts plasminogen to plasmin).
iii. Collaginase - Breaks down collagen.

Front 170

What are some of the toxic structures?

Back 170

Gram negative bacterial LPS (is en endotoxin) == Lipase A

Penton Base of Adenoviruses

Nucleocapsid of Rabies virus acts as a superantigen

Front 171

How does fungus affect the cell?

Back 171

The most probable cause is physical growth thru the tissues.

Front 172

What is a systemic inflammatory response syndrome (SIRS)?

Back 172

Endotoxic Shock (septic shock, sepsis). = inflammatory response due to high levels of endotoxin.

Can occur to other bacterial cell components ==> peptidoglycan, teichoic acids and fungal cell wall components.

Front 173

Compare and contract endo and exo toxins.

Back 173

Exotoxin are:
- needed in small amounts
- specific to cell type
- form toxoids
- do not usually stimulate fever
- secreted from live cells

Endotoxins are:
- required in high doses
- cause systemic effects, fever, inflammation.
- Composed of LPS on cell wall
- Do not form toxoids
- Are pyrogenic (fever stimulating)
- released when bacterial cells lyse.

Front 174

Describe the mechanism of action of ADP-Ribosylation:

Back 174

Addition of ADP-ribosyl group (removed from NAD) onto functional cell protein -> change in function/inactivation of the target protein.

Various effects depending on:
-> Cell Type
-> Specific intracellular target site.

Front 175

Describe ADP-Ribosylator in Diphtheria toxin:

Back 175

Produced by Corynebacterium Diphtheriae.

Toxin is bacteriophage-encoded

Normally repressed - expression is triggered by low levels of iron.

Target: Elongation Factor - 2 (involved in protein synthesis).

Front 176

Describe ADP-Ribosylator: Cholera Toxin

Back 176

Produced by Vibrio Cholerae

Binds to GM1 receptors

Target: Gs( heterotrimeric G protein involved in control of adenylate cyclase).

Cholerae Toxin:

ADP-Ribosylation of alpha-subunit of Gs - > Gs locked into activated state (GTP bound state) -> Increase in cAMP -> Activation of Protein Kinase A -> Abnormal phosphorylation of chloride channels - > Stimulates secretion of Cl- and Water / inhibits absorbption of NaCl -> Sever Fluid Loss causing electrolyte imbalance.

Front 177

Bacterial toxin can also cause Pores. what is that?

Back 177

Also referred to as CFTs = Channel Forming Toxins: Class II exotoxins.

Effect: Cell death occurs due to osmotic lysis or apoptosis.
Mechanism: Protein pore destabilizes membrane.

Front 178

What is phospholipid membrane destabilization mechanism of exotoxin?

Back 178

Effect: Indiscriminate lysis
Mechanism: Destabilize cell membrane by removing polar head groups from phospholipids.

Advantages to bacteria: eliminates host defenses, creates nutritionally rich environment.

Front 179

How does bacteria kill by Zinc Metalliendoproteases?

Back 179

Proteolytic cleavage of toxin -> 2 linked fragments:
a. light chain (LC) -> enzymatically active: zinc metalloprotease
b. heavy chain - binding & translocation.

Front 180

Describe how super-antigens work/

Back 180

They are class I exotoxins. Interfere with host immune response coordination - > divert/confuse host defenses.

Interact directly with T-cells and Antigen Presenting Cells: Important controbuter to damage observed.

Binds directly to T-cell receptors -> 20% of T-cells activated (normal is 0.01% of T-Cells activated).

Front 181

What are toxoid-based vaccines?

Back 181

Toxoid = inactivated exotoxin ( exposure to chemicals, heat, etc.).

Still antigenic but no longer capable of directly causing damage.

Currently used in: Diptheria toxoid
Tetnus Toxoid

Front 182

What are pathogenicity islands?

Back 182

They are clusters of genes encoding for virulance features such as:
- Toxins & Approp. secretion system
- Superantigens
- Iron uptake systems/Siderphores
- Adhesins

Tend to be present in pathogens but missing in same/ related non-pathogenic species. Often associated with mobile genetic elements (plasmids, transposons, etc.)
---> Acquisition of whole PAI could switch the bacteria from avirulent to virulent type.

Front 183

How does bacteria coordinate its virulance response?

Back 183

Using a two-component transduction system (TCSTS).

It is widely distributed in bacteria
Bacteria may have multiple TCSTS
Function: co-ordinate bacterial response to environmental stimuli.

Components:
(1) Sensor (S) located in cytoplasmic membrane -->
[it monitors stimuli, then singles]
(2) Response Regulator (RR) located in cytoplasm. -> altered gene expression, changes in flagella movement, etc.

Stimuli: pH, nutrition levels, redox potentials, etc.

Example: Vibrio Cholerae
Signals: pH, temperture
Sensor: ToxS
Response Regulator: ToxR

Response: Synthesis of cholera toxin and pilli.

Front 184

Bacteria has a problem obtaining iron, how does it do it?

Back 184

i.Synthesis of surface receptors that can grab the host's iron chelators.
ii.Synthesis and secretion of siderphores
-> Low molecular weight compounds
-> High Affinity for iron.

Front 185

What are some of the difference mechanisms of the body and how does bacteria evade it?

Back 185

1. Complement: Evaded by:
- Capsules
- Complement-Binding Proteins
- Proteases
- Host Cell Mimicry

2. Phaogocytic Killing is evaded by:
- Capsules
- Type III secretion systems
- Intracellular Parasitism

3. Antigen Processing is evaded by:
- Interfere with MHC function and antigen processing.

4. Antibodies is evaded by:
- Ig-binding/inactivation proteins
- Antigenic Variation

5. Apoptosis is evaded by:
- "decoy" proteins (viral Bcl-2 homologues).

Front 186

What are the components of a capsule?

Back 186

-Polysacharaide
-Polyribose Ribitol Phosphate
-Hylauronic Acid

Front 187

What is "host cell mimicry"?

Back 187

Not "seen" as a foreign cell so no phagocytosis/opsonization.

Front 188

Describe how bacteria and viruses evade host antibodies?

Back 188

Bacteria:
a. ig-binding / inactivation proteins
-> Bacterial IgA protease (secreted) inactivates sIgA by proteolysis. Direct binding of bacterial cell wall protein to Fc domain.
b. Antigenic / phase variation
-> Antigenic variation = Multiple antigenic forms can be expressed at different times. (i.e. N. Gonorrhoeae) contains more then 1 copy of pileE and multiple copies of pilS (transcriptionally silent). Recombination between these results in different pilins.

Phase Variation: can switch protein expression on and off, results in lots of different phenotypes which is beneficial for survival.

Viruses:
Antigenic Shift and Drift:
- Composition of key surface glycoproteins can change slightly (drift) or dramatically (shift).

Front 189

What is biofilm? How is it formed?

Back 189

Biofilm: Bacterial and/or fungal attachment to a tissue/artificial surface and production of a covering layer of Exopolymetric Substance (EPS).

Types of surfaces that can have biofilm formation vary widely:
-> Tissues
-> Heart Valves
-> non-shedding surfaces
-> Artificial Joints
-> Indwelling medical devices (e.g. catheders, artificial heart valves, sutures).

Can be single or multi-species depending on location:
-> endocarditis is usually single species
-> Dental Plaques is usually multiple species (>50).

Why are biofilms important?
-> they are an important cause of bacterial infections.
-> Attachment upregulates some genes and downregulated others.
->Free-floating "planktonic" bacteria behave,communicate and respond very differently to attached (i.e. biofilm) bacteria.
-> Biofilms are different: growth rates, community interactions, susceptibility to antimicrobial agents and components of immune response.

Examples of Infections involving biofilms:
- Dental Caries, Peridontitis
- Otis Media
- Osteomyelitis
- Necrotizing Fasciitis
- Pneumonia
- Endocarditis

Front 190

Organs move within the body to another location, why is it necessary? And how do they do it?

Back 190

Why is it necessary?
i. Enables movement to another site(s) within the body.
-Might be a location that is less accessible by the immune response
- Organisms may have a tropism for a particular location / tissue (i.e. nutritional requirements).

They can move via:
a. Direct Movement
-in surface fluids, flow of intestinal contents, facilitated by toxin production, growth throught tissues, from cell to cell.

b. Via nerves
(used by some viruses usually, i.e. Rabies).

c. CSF
- Cross the blood-CSF junction (choroid plexus). Generally requires movement into the blood stream first.

d. Blood (hematogenous)
- Can be in the blood or blood components e.g. Plasma: B.anthracis

e. Lymphatics or immune system cells.
- Moves from tissue fluids into lymphatic capillaries.

Front 191

Define what a secondary site for viral replication is.

Back 191

- When the bacteria spreads from the initial site to another site, usually facilitated by establishment of viremia.
- Secondary site of replication is often key in determining associated symptoms.

Secondry site maybe a site for bacterial replication and shedding. Some viruses remain localised, replicate locally and do not usually spread.

Viremia = entry into the blood stream.

Front 192

What is transmissibility?

Back 192

Number and Period of time organisms are shed for.

-Varies significantly from one species to another.
- This is what defines how long an infected individual remains infectious for.

Front 193

Define some possible ways / routs of trasmission?

Back 193

1. Vertical Transmission
(Mom-->Child)
2. Direct Contact
3. Arosol / Cough Droplets
4. Fecal-Oral
5. Sexual Transmission
6. Environmental Reservoir
7. Insect & Animal Vectors (Zoonosis).

Front 194

What are some intrinsic and extrinsic factors which define the stability / survival of a microbe?

Back 194

Microbial Factors:
-> Sensitivity to UV damage
-> Ability to resist drying

Extrinsic Factors:
-> Humidity
-> Temperature
-> Exposure to Disinfectants

-> Infectious dose also can contribute (i.e. the number of cells to cause an infection):
-> Depends on site of entry and route of infection
-> Varies with different microorganisms

Front 195

How can transmission occur?

Vector/Vehicle

Back 195

Transmission can occur via vehicle or vector:

Vectors are usually animals or insects.

Front 196

What is shedding?

Back 196

Shedding is the release of microorganisms in fluids, on cells or in secretions from a site (usually the same site the microorganism gained entry via).

Front 197

How can infection enter the body?

Back 197

Skin (directly from lesions or on desquamated epithelial cells).

Respiratory Tract (Aresols are produced during normal speech, breathing and during coughing and sneezing. Increase in volume of secretions increases the chance of transmission. Particle Size Varies (small droplets -> remain suspended indefinitely).

Gastrointestinal Tract: All organisms that infect the GIT are shed in faeces. Diarrhea increases fecal contamination of environment.

Genitourinary Tract: Urine is normally sterile. To infect urine, organisms must spread to the kidney or bladder or attach to urethral epithelial cells.

Body Fluids:
Various: Blood, Saliva, Milk, Semen.

Front 198

What is the difference between apical and basolateral viral shedding?

Back 198

Release to apical surfaces: facilitates shedding and dispersal into e.g. air / feces: These tend to be localized/limited.

Front 199

Define some routs of entry of microbes?

Back 199

Mucosal:
1. Airway via inhaled droplets and spores
2. Gastrointestinal Tract via contaminated food/water.
3. Genitourinary tract via Physical contact.

External Epithelia:
1. External surface via physical contact
2. Wounds and Abrasions via minor skins abrasions, puncture wounds, Handling infected animals.
3. Insect bites via mosquito or via Deer tick.

Front 200

What are some of the defense mechanisms that humans have against disease?

Back 200

2 Types:
1. Fist line of defense:
-> Innate immunity (non-specific)
-> present from birth
-> DO NOT rely on Antigen-Antibody reaction
-> Provide Immediate Response
-> Operate Regardless (i.e. does not require prior memory).

Second Line:
-> Specific Immunity

Front 201

What is specific immunity?

Back 201

1. Those that prevent Entry of pathogen (Physical, Chemical, Mechanical)
-> Barriers, Removal by washing, Natural antimicrobials.
2. Those which inhibit growth of pathogen (following its entry).
-> Leukocytsis, Phagocytosis, Inflammaton, Fever, Complement, Interferon.

Front 202

What are some of the physical barriers that prevent pathogen entry?

Back 202

-> Skin - A physical and chemical barriers.

-> Mucous Membrane - Line open cavities, a physical and chemical barrier, it is moist.
Goblet Cells Secrete MUCUS which traps microbs. Mucus contains:
-> Lysozyme
-> Secretory IgA
-> Lactoferrin
-> Lactoperoxidase

-> One Way Check-Valves - Separates regions, maintains sterility. [e.g. Ureteric Valve - Bladder is low sterility and Kidneys is high Sterility].

Front 203

Define some routs of entry of microbes?

Back 203

Mucosal:
1. Airway via inhaled droplets and spores
2. Gastrointestinal Tract via contaminated food/water.
3. Genitourinary tract via Physical contact.

External Epithelia:
1. External surface via physical contact
2. Wounds and Abrasions via minor skins abrasions, puncture wounds, Handling infected animals.
3. Insect bites via mosquito or via Deer tick.

Front 204

What are some of the defense mechanisms that humans have against disease?

Back 204

2 Types:
1. Fist line of defense:
-> Innate immunity (non-specific)
-> present from birth
-> DO NOT rely on Antigen-Antibody reaction
-> Provide Immediate Response
-> Operate Regardless (i.e. does not require prior memory).

Second Line:
-> Specific Immunity

Front 205

What is non-specific immunity?

Back 205

1. Those that prevent Entry of pathogen (Physical, Chemical, Mechanical)
-> Barriers, Removal by washing, Natural antimicrobials.
2. Those which inhibit growth of pathogen (following its entry).
-> Leukocytsis, Phagocytosis, Inflammaton, Fever, Complement, Interferon.

Front 206

What are some of the physical barriers that prevent pathogen entry?

Back 206

-> Skin - A physical and chemical barriers.

-> Mucous Membrane - Line open cavities, a physical and chemical barrier, it is moist.
Goblet Cells Secrete MUCUS which traps microbs. Mucus contains:
-> Lysozyme
-> Secretory IgA
-> Lactoferrin
-> Lactoperoxidase

-> One Way Check-Valves - Separates regions, maintains sterility. [e.g. Ureteric Valve - Bladder is low sterility and Kidneys is high Sterility].

Front 207

What are some chemical barriers (body secretions) to microbes?

Back 207

1. Lysozyme - (present in our tears) attacks bacterial cell wall
2. Salt and Sebum - Maintains skins pH of 5.5. Salt from sweat glands. Sebum (Fatty Acids) from sebaceous glands and normal flora metabolism.
-> Inhibit growth of streptococci, fungi and most gram negatives

3. Gastric Acids (Stomach) - Hydrochloric acid (pH 1.2 - 3.0), produced by parietal cells, most microbes are sensitive,

4. Lactic Acid (Vagina) - Post-pubescent and pre-menopausal women. Their normal flora has Lactobacillus sp. which produces lactic acid, maintains the pH at 4 to 4.5 and prevents gardnerella vaginalis and chlamydia trachomatis.

5. Bile (Aids in digestion in small intestine).
-> Steroids (deoxycholic and cholic acids)
-> Conjugated with glycine and taurine (detergent proporties)
- Inhibits growth of gram +ve microbacteria.
- Conjugated Bile Salts: -> Aa's: antiviral.

6. Oxygen (Osmotic Pressure)
7. Transferrin and Lactoferrin
-> Bind ferric ions: reduce free iron concentration
-> Inhibit growth of bacteria and fungi

Spermine (Seminal Fluid)
- pH 7.7
- Aliphatic amine
--> shown to kill Stphylococci and M. tuberculosis.

Front 208

How does the Normal Flora help protect us?

Back 208

The microbes that reside on the body of healthy individuals create an ecosystem ( a biological community )
- > sometimes referred to as commensal flora

They protect against potentially harmful micro-organisms by:
1. Bacterial Antagonism
-> Competition: for nutrients and attachments sites on cell surfaces
2. Production of inhibitors: Bacteriocins, Antibiotics, Toxic Metabolic end products.

3. Stimulate the immune system: by being present they help build an adaptive immune response.

Front 209

The estimated number of bacteria in the human body is:

Back 209

Exceeds the number of human tissue cells by at least a factor of 10.

Front 210

What are some of the mechanical barriers to the microbial?

Back 210

1. Physical Flushings
-> Tears, Saliva, Urine, Mucus
--> Washes Area
--> Dilutes Microbes
--> Disrupts colonization of pathogens.

2. Reflexes
--> Coughing, Breathing, Sneezing, Vomiting, Diarrhoea.
--> Remove pathogens from sites.

Other Mechanisms:
- Ciliary Escalator (Respiratory Tract): Mucus moves upwards
- Desquamation: Sloughing of dead cells
--> Removes pathogens
--> Prevents colonization

Front 211

What are some of the pathogenic inhibitions when the bacteria is already inside the body:

Back 211

1. Leukocytosis
-> Increase the number of white cells
->Tissue inflammation stimulates leukocytosis (systemic immune response).

Remember White Blood Cells:
-> Neutrophils: protect against bacteria
-> Lymphocytes: protect against viruses, bacteria and fungi
-> Eosinophils: protect against parasites

2. Phagocytosis:
-> bye WBC
-> For bacteria: initially neutrophils then microphages replace neutrophlils.
Activity: Engulf, kill and digest pathogens.

NOTE: Capsulated bacteria are REISISTANT and Intracellular Organisms are REISISTANT to PHAGOCYTOSIS.

3. Inflammation:
-> Localized tissue repose to injury.
-> Characterized by redness, pain, heat and swelling.

Purpose: confinement & destruction of pathogen; repair / replace damaged tissues.

Chemical Mediators: Histamine, Prostaglandins, Leukotrienes, Nitric Oxide, Platelet Activating Factor, Cytokines (IL-1, TNF).

Function: Inflammation, bronchial smooth muscle constriction, increase mucus production.

Front 212

What are Pyrogens?

Back 212

Substances which a fever, usually endotoxins from gram -ve bacteria.

Front 213

Alternate complement pathway DOES NOT...

Back 213

involve C1, C2 or C3.

Front 214

What is the first defense against a virus?

Back 214

interferons

Human produce: INF-alpha, INF-beta, INF-gamma

Released by virally infected cells: INF-alpha and INF-beta

Released by uninfected cells: INF-gamma

Action: reversibly inhibit normal cell function; interferes with viral replication.

Front 215

What are the various levels of infection?

Back 215

1. Inapperent Infection
-> No symptoms at all. Infection aborded. Immune response may be present.
2. Subclinical Infection
- Patient is aware he is ill, may present to the doctor.
3. Clinical Infection
-> Victim becomes patient by going to the doctor / physician.

Front 216

What do IgG and IgM do?

Back 216

- Activate the Classical Component Pathway. (IgM does it better).
- Serve as Opsonins
- Neutralize Toxins Directly
- Neutralize most viruses
--> by blocking tissue receptors
- Precipitate soluble antigens

Front 217

What does the Alternative Complement Pathway do?

Back 217

-Its non-specific ( does not care for antigen-antibody reaction ).
-Activated by unrelated substances found in the cell walls of many bacteria and fungi.
- Lipopolysaccharide (LPS)
- Aggregated IgA

Result in Destruction of microorganisms.
- Opsonization
- MAC (Membrane Attack Complex).

Front 218

What does the Classical Complement Pathway do?

Back 218

It is dependent upon antigen-antibody complex so it is specific.

It is activated by IgG and IgM when they are bound to their appropriate target antigens.
- Mainly bacteria and Fungi
- Not effective against intracellular infections (Viruses, etc.)
- Not effective against multicellular pathogens, particularly Helminth.

Results in destruction of microorganisms.
- Opsonization
- MAC (Membrane Attack Complex)

Front 219

Describe a localized anaphylactic reaction.

Back 219

-Triggered by complement Fragments (C3, C5, C3a, C5a)
- Contraction in various luminal sites.
--> Illum
--> Bronchii
--> Uterus
--> Vascular Smooth Muscles

Release of additional inflammatory mediators:
-> Histamine

Front 220

The mechanism of innate/adaptive immune response primarily depend on?

Back 220

WHER (LOCATION) the invading organism goes. Can be:

1. Outside the cell (Extracellular)
2. Within the phagosome (Intracellular)
3. Within the cytosol (W/in the cytosol)

Front 221

What are the extracellular invaders?

Back 221

Nearly all helminth (too large)
Most protozoa (too large)
Most Fungi remain outside the cell
Many Bacteria
Bacteria
-> Nisseria
-> Straphylococcus
-> Streptococcus
-> The Enterobacteriaceae
-> Vibro Sp.
NOT VIRUSES ( they need an intracellular environment).

Front 222

Which organisms can be found intracellularly (phagosome)?

Back 222

Fungi: Histoplasma sp.
Bacteria: Mycobacterium Tuberculosis
Chlamydia:
-> C. trachomatis
-> C. psitacci
-> C.pneumoniae

Mycoplasma Sp.

Front 223

What is the fate of the Microorganisms within the phagosome?

Back 223

Most Microorganisms are rapidly killed and digested via:
- low pH
- Hydrolytic Enzymes

Some can survive within the phagosome.

(Salmonella Enteritidis -> secretes a protein that blocks fusion of lysosome and phagosome)

(Mycobacterium - able to keep TACO, so prevents fusion of lysosome and phagosome).

Front 224

What are the cytosol microbes?

Back 224

Protozoa: Plasmodium Sp.
Fungi: Histoplasma Capsulatum
Bacteria: Treponema Sp.
Most Viruses.

Front 225

What is the defense against Cytosol Microbes?

Back 225

In most cases, some of the invading microboes are broken apart and their antigens are expressed on outer surface of the infected cell.

CD8 and T-Cell DEFENSES ARE ACTIVATED.

Front 226

How is immune clearance mediated?

Back 226

- Digestion by phagosomes (Either as an intact cell or in fragments after T-cell or Killer cell attack, Expelled within the bodies of dead phagocytes)

- Precipitated and Deposited in anatomical "Sinks" (Synovial Capsule of Joints, Glomerular Basement Membrane, Vascular Walls).


- Forcibly expelled by Allergic Reaction (sneezed, coughed, vomited out)

Front 227

What is immuno-mechanis?

Back 227

- No covelant bonds are being made or broken
- No enzymes are involved
- No dramatic consumption or release of energy is involved.
- Basic Reactions are always easily reveresed
- Most reaction result in change in solubility (or colligative properties) of the reactants
- Occasionally a secondary reaction is triggered.

Front 228

Describe the orders of antibody-antigen reactions?

Back 228

First Order: Physical Binding of the Ab to the Ag.
Second Order: A change in colligative proporties of the reactants
Third order: A chemical pr physical reaction that is triggered by the first or second order reactions.

Front 229

Describe Affinity and Avidity?

Back 229

Affinity: strength of the single physical bond formed between an Fab and its matching epitope

Avidity: is the aggregate stregth of all bonds formed. Valences of the Ab molecules and multivalent Ag's serve to multiply the force of single bonds.

Front 230

Which antibodies are usually used for tests and reaction?

Back 230

IgG and IgM

Front 231

What is a DIRECT agglutination reaction?

Back 231

Add anti-globulin to suspension of particles SUSPECTED of having Ig already bound to their surface.

Agglutination happens only if such are present.

Used to magnify an agglutination reaction, or cause on if the only antibody present is IgG.

Examples:
- Blood banking crossmatch
- Testing mothers-to-be for Anti-Rh antibodies.

** Detects antibodies already present / bound to the surface of a cell **

Front 232

What is an INDIRECT agglutination (Coombs) test?

Back 232

- Can be used to detect either antibody or antigen, depending on set-up.
- Used to magnify or enhance weak or non-existent agglutinations caused by specific IgG.

Example Blood Banking Crossmatch:
- Test Donor Cells with Recipient Serum
- Test Donor Serum with Recipient Cells.

Front 233

Parovoviridae is a ?
How does it protect its DNA?
What are the subfamilies of the Parovoviridate?

Back 233

-singe-stranded DNA virus.
-it has "terminal repeats" at both ends.
- These herpins act as DNA primers to synthesize double Stranded DNA.
- DNA capacity is to code three proteins.

Two subfamilies:
- Densovirinae - infect athropods
- Parovirinae - Infecting birds and mammals.

Front 234

Describe the autonomous virus-B19

Back 234

Part of the parvovirine family:
- Needs active growing human cells
- Infects immature erythrocytes.
- If people have, sickle cell anemia or thelassemia then the virus causes Transient Aplastic Crisis.

Reoccurance is due to : Heat, Stress, Sunlight and exercise. Transmitted via placenta or respiratory route.

Virus Causes: Erythmea Infectiosum,
incubation period ranges.
Symptoms: Fever, Malaise, Headache, Itching, Confluent and Indurated Rash on face which spreads to legs and arms in 1 - 2 days. Lymphadenopathy and Splenomegaly are observed.

Front 235

Describe the Herpes virus:

Back 235

- linear double-stranded DNA.
- Icoshedrial symmetry.
- Causitive agnets that are similar in morphology, basic mode of replication and capacity to establish latency and reccurent infections are not grouped under HERPESVIRIDAE.
- Subdivided into:
1. Alphaherpesvirinae
2. Betaherpesvirinae
3. Gammaherpesvirinae.

Front 236

Describe Alphaherpesvirinae:

Back 236

- Short replication cycle (6-7 hrs).
- Infections is cytolytic for most cells.
- Persistent in macrophages and lymphocytes and latent in neurons.
- HHV 1 , 2 and 3 .

Front 237

Of the Herpes Simplex viruses which ones go to trigeminal ganglion and which go to sacral ganglion?

Back 237

Trigeminal: HHV 1
Sacral: HHV 2

Front 238

What are some of the symptoms of HSV-1?

Back 238

- Gingivostomatitis
- Eczema Herpeticum
- Herpes Labialis (Fever Blisters)
- Herpes Whitelow (Blisters on hands).
- Herpes Encephalitis (affects brain).

Front 239

What are some of the symptoms of HSV-2?

Back 239

- Genital Herpes
- Neonatal Herpes (75% infections acquired via birth). Mortality is high (50%) and the survivors may exhibit permanent neurological impairments.
- Herpes Meningitis - complication of HSV2, not as serious as Herpes Encephalitis ( caused by HSV-1).

Front 240

What is the treatment for Herpes 1 and 2 ? what is the mechanisms?

Back 240

Treatment: Acyclovir:

Mechanism: Selective against HHV infected cells.
1. Acyclovir is phosphorylated by virus encoded thymidine kinase to acyclovir-monophosphate, which in turn is converted into Acyclovir-tri-phosphate by cellular enzymes. This triphosphate of the antiviral acts as an inhibitor of viral DNA synthesis and substrate for the HHV DNA polymerase.

Can be used topically, intravenously or orally to suppress frequent recurrences.

Front 241

Where is the primary infection of Human Hepes Virus 3(Zoster)? What are the intranuclear inclusions called? What are the major clinical symptoms?

What about Latent Infections?
What about Recurrent Infections?

Back 241

1. Resiratory Tract
2. Intranuclear (Cowdry) and Giant Cells Develop.
3. High Fever, Rash in DIFFERENT stages of development. Immunocompramised patients develop progressive severe varicella.
4. Latenet Infections are asymptomatic with no viron or viral proteins being detected. Viral DNA reides in the doral root ganglia.
5. The virus travels down to the sensory nerve fibers and infects epithelial cells innervared by the fiber. Infections are painful vesicular eruptions localized to the dermatome, normally in scalp or thorax. Severe systemic infections in immuno-compramised individuals are seen.

Reactivation of the latent virus due to
- radiaion
- transplanatation
- malignancy

Front 242

Quickly Describe Betaherpes Virus?

Back 242

Long viral replication cycle (48-72 hours).
Infeced cells are swalled (cytomegaly) but not lysed.
Latency in Glands and Kidney.

Front 243

What is Cytomeglavorus (HHV5)?
- Who is infected
- How is it spread
- Where is it found, target cells?

Back 243

Most infection are subclinical
The virus spreads through contact with infected urine, saliva and breat milk. It is also found in semen and genital secretions. Children shed the virus for a long time. Epithelial cells in the oropharnyx are the primary target cells.

You get cowdry bodies (intranuclear) with giant cells in infected salivary glands, spreading to lyphoid tissue culminating in viremia.

~50% of babies are found to be infected when the mothers were infected during pregnancy.

Latent Infection:
Life long infection as common with other Herpes viruses.
Virus is shed in Saliva and Urine for months to years after primary infection.

Major Clinical Syndromes:
1. Congenital Infections
Only abot 20% of all infants with congenital CMV are symptomatic with jundice, microencephly, hepatospleenomegaly and lethargy.

The asymptmatic infants develop viruria within 1 week after birth and continue to shed for a long time.

2. Prenatal CMV:
Vast majority of cases are asymptomatic
Pneumanotis may be seen occasionally during the first 3 weeks.

Diagnosis:
Observed of Cytomegalic Cells.
Virus is isolated from saliva and urine.
EM (if avalible) observation of virus in urine is he simplest and quickest test.
RIA and ELISA are common lab tests.

Treatment:
Gancyclovir. Acyclyc Guanosine analogue, decreases virus shedding in all patients.
Acycovir, HHV is resistant to acycovir. No viral thymidine kinase is synthesized. Human Leukocyte interferon delays virus shedding but not a cure.

Front 244

Human Herpes Virus-6 (Betaherpesirinae). Describe it?

Back 244

The virus replicated in T-cells
Latency is established in resting cells.
Mitogenic stimulation of the virus in infected cells causes lysis of the cells.
Clinical significance is not known.

Primary Infection:
Happens in early infancy, but no evidence in reactivation in adults.

Major Clinical Syndromes:
High Fever w/ Rash.
Isolated from Saliva and Kidney of patients.

Front 245

Human Herpes Virus - 7 (Betaherpesvirinae)

Back 245

Isolated from CD4 T-lymphocytes from healthy individuals. The virus is most closely related to HHV-6
Children under the age of 2 are infected.
About 97% of all adults are serogically positive.
Clinical relevance of association of the virus with healthy individuals is unkonwn.

Front 246

Describe Human Herpes Virus -4 (Epstein-Barr Virus)?

Back 246

Primary Infection:
1. Distribution of the virus is worldwide especially in yound adults.
2. Not found in children
3. Symptoms are: non-speciic febrie illness associated with upper respiratory infections,pharyngotonsilitis, rash, lymphodenopathy and pneumonia.
Adolescent Infection are more common.

Oral transmitssion with virus shedding in saliva of infected individuals. Virus replicates in parotid glands and gains enterance into the blood infecting B-Cells. Dissimination of the viurs is via the lymphoreticular system.

It remains Latent in blood, lymphoid tissue and throat of individuals. Activation by unknown mechanism.

Major Clinical Syndromes:
1. The disease is common in young adults and rare in children.
2. Half the patient show tonsillopharyngitis with thick exudates.
3. Hepatomegaly is ovserved in 10% to 15% of the patients.
4. In immunosupressed patients EBV is associated lymphomas are common due to functional T-Cell Defect and NK cell defect.

6. Treament: Usually self-limiting disease requires supportive measures. NO CONTACT SPORTS due to spleenomegaly. EBV is inhibited in vitro by Vidarabine and Acyclovir. Clinical trials are inconclusive.

Front 247

Burkett's Lymphoma and Nasopharyngeal Carcinoma are increased with?

Back 247

EBV infection. Burket's Lymphoma is reported in central Africa and Nasopharyngeal Carcinoma is seen in China.

Diagnosis:
Presense of enlarged lymphocytes in he peropheral blood ( Downy Cells ). Detection of viral DNA in biopsy material. Detection of EBV capsid proteins and/or of EBNA in infected cells. Serology, ELISA and FAT coupled with a four-fold increase in the titers. Salivary IgA and NPC. Winged Scapula - paralysis of Serratus Anterior.

EBV is present in over 90% biopsies from these lymphomas and carcinomas. Higher titer of antibody against EBV capsid proteins and early Antigen {Epstein-Barr Nuclear Antigen (EBNA)} are detected in these patients.

Front 248

Which virus causes Kapos's Sarcoma?

Back 248

Human Herpes Virus-8 (Gammaherpesvirinae)

Front 249

Describe the Papovaridae Virus?

Back 249

1. Double Stranded DNA
2/ Super Coiled Circular.

All members have the potential to induce tumors in small animals. Produce natural and Chronic infections in the natural host. Members associated with human disease are: Papilloma Virus and Polyoma Virus.

Front 250

Describe the human papilloma virus?

Back 250

Important points:
1. Free Episome associated with benign tumors.
2. Random integration or part of the genome is essential for malignancy.

Major Clinical Symptoms:
1. HPV-6 and 11 cause laryngeal papillomas in children and anogenital (condylomatous) warts.
2. HPV 16 and 18 are associated with cervical cancer and is one of the most common STD throughout the world.
3. PCR is the gold standard for diagnosis.

Treatment:
Removal of infected Epithelium.

Front 251

Describe the Poxiviridae (Causing poxvirus)

Back 251

1. Nucleic Acid, Double Stranded DNA, Linear with cross linked termini, Capsid Symmetry is complex. Envelop is present.

2. Produce Skin Lesions. DNA viruses replicated in the cell cytoplasm. Virus coat is not acquired by budding and not necessary for infectivity. Recombinant vaccina virus is good for delivery of antigen from other highly contagious microbes, inserted into the vaccine genome.

3. Eosinophilic Cytoplasmic Inclusion Bodies (Guarnieri Bodies).

Front 252

Describe smallpox. (Variola Major / Minor)

Back 252

Impossible to destinguish the two viruses. Virus replication in the upper respiratory tract from where it gains entrance into the lymphoid and then into the blood. A generalized skin rash then appears. Rash develops first on the face and hands and then on trunks and legs. Progression of the rash is always from:
Macule --> Papule --> Vesicle --> Pustule --> Scab.

Lesions are more common on face then on trunk.

Only one stage of lesions are present at a time.

Severe Disease is hemmorhagic and fatal.

Front 253

What is Vaccinia (pox virus)

Back 253

Virus has several antigens common to variola but, distinct from cowpox.

Used for vaccination against virus. Vaccine produced lasti variola ng immunity. Because of stability of the virus against various disinfecting agents it allowed delivery to remote areas with out virus inactivation.

No asymptomatic or undiagnosed cases are reported. Recombinant vaccina virus not being developed to deliver many immunogens for vaccination.

Complication are rare but in immunocompromised patients it can lead to encephalitis and death.

Front 254

1. What is Monkey pox (pox virus)
2. What is Molluscum Contagiosum?
3. What is an Orf?
4. What is Tanapox/

Back 254

Clinically indistinguishable from small pox. Human infections recognized in West and Central Africa following eradication of smallpox. Recently there are many epidemics of monkey pox reported in the US.

2. Mainly it is an infection of children and young adults. Chronic proliferative process on face, back, legs, buttocks, anus, and genitals. Sexually transmitted, often confused with herpes virus.

Diagnosis: Guarnieri Bodies in the cytoplasm

3. Orf: Known as a contagious pustular dermatitis. NO Cytoplasmic inclusion bodies are developed. Diagnosis is via electron microscope.

4. Tanapox: Newly identified poxvirus with more than three epidemics occurring in Kenya.
Self-Limiting. PUSTULATION never occurs. Diagnosis via Electron Micriscope.

Front 255

What are some of the treatments for Pox virus?

Back 255

Isatin-B-thisemicarbazone (IBT) and N-Methyl IBT (Marburan). Inhibits late mRNA synthesis so no capsids are made.

Rifampin

Inhibits some events in viral morphogenesis.

Immature virus emerges w/out surface spicules due to mutations in 62K proteins.

Front 256

Describe the RUBEOLA virus:

Differentiate between Rubella?

Back 256

1. Contains single stranded negative polarity RNA (ss (-) RNA). It has Hemagglutinating and Fusion activities. It replicated in cytoplasm of infected cells. There is only 1 serotype.

The exantheme is called Measles which spreads through the respiratory droplets. It is febrile illness with High Fever/Cough, conjuctivities, coryza and a maculopapular rash.

Koplik's Spots are pathogenic for any early rubeola diagnosis.

Complications:
1. Bronchopneumonia
2. Otitis Media
3. Encephalaties.
4. Gant Cell Pneumonia
5. Bacterial Pneumonia
6. Subacute Scelerosing Panencephalities (SSPE)

Rubella:
Single-Stranded (+) RNA. Contains Hemagglutinin and NO fusions peplomers. The disease is called German Measles.

Symptoms include Mild Fever, Malaise, Conjuctivitis, Coryza and a maculopapular rash. Auricular lymphadenopathy and/or are also reported in some Polyartritis cases.

Diagnosis: Generally on clinical symptoms and detection of anti-ruella IgM in acute phase serum. Interference assay.

Complications:
1. Congenital Rubella
2. Cataracts and Deafness
3. Mental Retardation
4. Heart Defects
5. Stillbirths

Front 257

What do you need to cause an infection in Respiratory Tract?

Back 257

1. By-pass host barrier defences and filtering system.
2. Come into contact with suitable tissue or surface.
3. Evade components of the immune response.

Front 258

What is the normal temp of URT and the predominant antibody?

Back 258

1. sIgA and 33 C.

Front 259

What is important about the lower respiratory tract?

Back 259

Bronchi and Bronchioles are lined with muco-ciliary blanket.

Normally Sterile (b/c of URT)

Front 260

Describe the Alveoli?

Back 260

No mucociliary blanket, no ciliated epithelial cells. Normally Sterile (because URT). Normal antibody is sIgA and tissue damage here can be significant b/c it can interfere with gaseous exchange.

Front 261

What is the difference between primary and secondary infectors?

Back 261

1. Primary: Invades healthy people.
2. Secondary: Invades only when there is already some damage. Such as Strep. Pneumonia attacks after an influenza virus infection.

Front 262

What is the difference between exogenous and endogenous infections?

Back 262

1. Exogenous Infections:
- Inhalation if infectious droplets
- Produced by talking, sneezing, coughing, etc.
- Inhalation of dust containing fungal spores.
- Self-inoculation by rubbing your eyes, nose, mouse.

2. Endogenous
- Comes from within, such as commensal bacteria after a heavy antibiotic load.
- Normal flora can move to an abnormal location.
- Preceding infection causes damage -> secondary infection.

Front 263

Why is it important to diagnose RTI?

Back 263

1. Because certain pathogen can cause/be associate with a sequel:
-> i.e. S. pyogenes can cause Rheumatic fever/heart disease.

Front 264

in RTI using what diagnosis test is good? Why is Culture media important?

Back 264

1. Sereoloical Tests - Used for viruses or difficult - to - treat bacterial pathogens. Complement Fixation. Elisa, latex agglutination.
2. Culture Media - Selective and differential media useful for elimination of normal flora.

Front 265

Specialized tests are required for the following pathogens:
- B. Pertussis
- C. Diptheriae

Back 265

1. Bordet-Gengou: potato starch glycol agar
2 Tinsdale Agar: Crysteine-Tellurite Agar.

Front 266

For S.Pyrogens you can use an in-office test, what about for Influenza virus?

Back 266

1. ASO test.
2. Rapid EIA's
- Results in 15-20 minutes
- Available for Types A and B
- Sensitivity and Specificity can range from 50-100%.

Front 267

Describe Adenovirus?
- Structure

Back 267

1.
-Icosahedral Capsid
-Non-enveloped
- Fibers on each of penton vertices
- Linear DNA
- Replicate in nucleus (basophilic nuclear inclusions).

Front 268

What are the two phases of viral replication of Adenovirus?
- E1-E4
- L1 - L5

Back 268

1.
-E1A - increase metabolism for viral replication.
-E1B - Blocks apoptosis
- E2 - Necessary for replication of viral DNA .
- E3 - encodes for products that interfere with host defenses.
- E4 - facilitates virus messenger RNA metabolism.

2. L1 - L5 required for virus production: structural components, encapsidation, etc.

Front 269

What is the pathogenesis of Adenovirus?

Back 269

- Fiber attaches to to host cell receptor
- Specific receptors are different.
- i.e. Serotypes 2 and 5 receptor is CAR (Coxsackie and Adenovirus receptor).

Penton base has toxicity:
- Inhibits Cellular mRNA synthesis
- Cell Rounding
- Tissue Damage

Viral Mechanisms to enable viral replication and evade host immune response:
- Interference with MHC Class 1 Expression (E3 binds to heavy chain).
- Interfered with effects of TNF
- Interfere with interferon-alpha and beta.

Front 270

What are some key epidimiological points about adenovirus?

Back 270

- Majority of cases occur in children.
- Military Recruits can get Acute Respiratory Distress Syndrome.
- Can Cause Pneumonia in Children, Military Recruits and immune compromised.

Front 271

Describe the Rhinovirus?
- Structural
- Pathogenesis

Back 271

Its from the picornaviridae family:
- Small: 28 - 30 nm.
- Icsahedral
- Non-enveloped

Genetic Material:
- ss (+) sense RNA (mRNA)
- Genome size of 7,000 - 8,500 kb (virus dependent).
- Replicate in cytoplasm

Preferred temperture of replication is: 33-35 C.

Pathogenesis:

- Attachment to ICAM1 via surface canyon/cleft.
- Replicate in and destroy ciliated epithelium of nasal and tracheal mucosa. Highest titers in nasal epithelium,

Rhinitis is probobly due to the host response to Rhinoviruses.
- Vascular Engorgement
- Increased Vascular Permeability
- Increase mucus production

Front 272

What is the MAIN mode of transmission for Rhianoviruses?

How do you treat it?

Back 272

- HAND
- Hard to treat b/c of many serotypes. Therapy based on clearing the symptoms.

Front 273

Describe the Coronaviruses?

Back 273

Genetic Material:
ss (+) linear RNA (Class IV)
Replicate in cytoplasm
Coronovirus S protein ("Spike") Protein.
- This protein:
+ Attach to proteins or carbohydrates receptor on host cells and enable fusion.
+ Antibodies against S protein are neutralizing
+ Helps in survival in GI tract.

Transmission: Mostly droplets but also Feco-Oral.

Front 274

Human Parainfluenza Virus:

Back 274

-Class V virus ss (-) RNA.
-Respirovirus: HPIV 1 and 3
-Rubulavirus: HPIV 2 and 3.

Has both Haemagglutinin and Neuroamidase.

Has Fusion Factor (F)
- Enables fusion of virus and host cell membranes
- There are antibodies directed against F proteins and are neutralizing.
Pathogenesis:
V proteins (fusion): role in evasion of immune response:
- Prevent apaptosis
- Alter cell-cycle
- Inhibit double-stranded RNA signaling
- Prevent Interferon biosynthesis

Associated with mild respiratory syndromes in range of age groups from Mild-Cold to Pneumonia.

Front 275

Describe the Respiratory Syncytial Virus?

Back 275

Family: Paramyxoidae.
Subfamily: Pneumonoviriniae
Genus: Pneumovirus

- Enveloped
- FUSION FACTOR - G glycoprotein in attachment.
- Two subgroups: A & B
- Lacks glycoprotein with HN activity.

Genetic Material:
- Linear ss (-) RNA (Class V)

Epidimiology:
Primary cause of serious lower RTI (LRTI) worldwide in infants and young children.
-> Main organism associated with bronchiolitis in children ( < 1 year of age).
Responsible for > 81% of cases
In same age group: causes > 50% of cases of pneumonia.
Can be singinifcant cause of LRTI (e.g. pneumonia) in elderly and immunocompromised.
It has worldwide distribution.

Front 276

What is the pathogenesis of Respiratory Synsitial virus?

Back 276

-Entry via epithelia of nose and eye.
-Large droplets may land on contaminated hands or surfaces (self-inoculation).
- F & G mediate attachment: F mediates membrane fusion.
- Primary site of replication = nasopharynx epithelial cells.

Can spread to lower epithelium after 2-5 days, resulting in bronchiolar epithelium necrosis, destruction of ciliated epithelium cells and infiltration of lymphocytes and mononuclear cells.

Immunopathogenic components are important for symptoms:
- CD 8+ T cells
- Subsequent disease shown to be enhanced when children vaccinated using heat-killed vaccine

Front 277

Influenza Virus:
- Family
- Genetic Material
- Antigens

Back 277

Family: Orthomyxoviridate.
Influenza has A, B, C subtypes.

It is enveloped and has Haemagglutinin and Neuroamidase.

Genetic Material: ss (-) sense SEGMENTED RNA
- 8 segments in influenza A and B
- 7 segments in influenza C.

Front 278

Subgrouping of Influenza A virus: Describe the haemagglutinin and neuroamidase.

Back 278

Haemagglutinin (HA)
- Rod/Spike - Shaped
- 25% of viral protein.
- Major antigen against which neutralizing antibodies are directed.

Requires Cleavage to be active:
- Carried out by cellular protease found only in RT.
- Availability of proteases may determine tissue tropism.

Neuroamidase (NA)
- Mushroom like tetramer with slender stalk = Sailidase Enzyme
- removes terminal sialic acid from glycoproteins and glycolipids.
- Enables budding of virus
- Helps virus moves through mucin layer to attach to epithelial cells.

Front 279

Describe the pathogenesis of Influenza virus:

Back 279

- Attachment Receptor: Sialylogosacharide
- Establishes infection in upper RT.
- Main site of replication = columnar epithelial cells.
- HA mediates fusion of the viron envelope to initate infected cycle via RME.
- Mature virus released apically: also spreads cell -> cell.
- Infection of mucosal cells - > cell destruction of the superficial mucosal cells.

Front 280

Describe the difference between antigenic drift and shift:

1. Drift
2. Shift

Back 280

1.
- Can involve any H or N antigens and genes encoding nonstructural protein.
- May be due to single mutation
- Selective pressure -> dominance of mutated strains
- Frequently occurs in Influenza A viruses, but also in B and C.

2.
- Sudden
- Major change in H or N genes (>50% affected)
- Can come from other animals (pigs/birds, mix of the viral gene)
- Shift occurs due to GENETIC REASSORTMENT between genes from different viruses present in a single host (may occur in animal or bird reservoir)
- New subtype is formed
- Population has no or low immunity

Front 281

What is the treatment for influenza virus?

Back 281

1. Amanatadine and Rimanatadine: prophylaxis of influenza type A

2. Oseltamivir
- Neuroaminidase Inhibitor
- Effective against Types A and B.

Prevention: Trivalent vaccine formulation
- Live attenuated
- Inactivated subvirons
- Surface antigen

Front 282

Describe in general the streptacoci bacteria.
- virulance factors
- labratory tests

Back 282

- Catalase Negative
- Gram +ve
- Fermentative Metabolism
- Two important groups:
+ Pyogenic Group: S. Pyogenis
+ Mitis Group: S. Pneumoniae

Major Wall Carbohydrates:
+ Lipoteichoic Acid
+ Group Polysacharide (cell wall carbohydrate)

Medically Important Streptococci:
- Strep. Pyogenes
- Strep. Pneumoniae

Virulence Factors:
Many. e.g. M protein of S. pyogenes

Labratory Identification:
-Lack Catalase
-Growth enhanced by CO2
- Nuritonally fastidious
- Normal Culture Medium = Blood Agar (BA)
++ Yeast Extract + Peptone + 5% blood ==> provides complex nutrients required (they lack TCA cycle).

Front 283

Describe Group A Streptococcus (GAS):

Back 283

Pyogen: induces pus formation
- due to leukocidin production

Appearence on Blood Agar:
- Beta- Hemolytic (not alpha like Strep. Pneumonia)
- Small Colonies
- Colonies lack pigment.

Virulence Factor: Pyrogenic Exotoxin. Causes Scarlat Fever.

Front 284

Describe Streptococcus Pneumoniae:

Back 284

1. Pneumonia = inflammation of the lungs.
In adults, bacterial pneumonia is the most common cause. In children and infants it is: RSV, HPIV, Influenza viruses A and B.

It is lancet-shaped, compare to short chains of cocci (in S.pyogenis).

Apperance in Blood-Agar:
- alpha-hemolytic
Optochin Sensitive and Bacitracin resistant.

Epidimilogy: Commonest cause of community aquired pneumonia. Member of nasopharyngeal microflora. Carried by 5-70% of individuals.

Front 285

Describe the pathogenesis of Strep. Pneumonia

Back 285

1. Capsule important as a key virulance factor.
2. sIgA protease
3. Pneumolysin
+ inhibits ciliated epithelial cell activitiy
+ Cytotoxic for alveolar and endothelial cells
+ Causes inflammation
+ Decreases PMN Effectiveness
4. Autolysin
+ Enables pnumolysin release by breaking peptide-cross linking
5. Ability to take up DNA through transformation.

** Penecillin Resistance is mediated through reduced affinity for B-Lactam antibiotics. **

Front 286

Describe Corynebacterium Diphtheriae:

Back 286

MAIN SYNDROME: PHARYNGITIS

Pleomorphic Rod: "Chinese Letters" arrangement.

Facultative Anaerobe.

Produces exotoxin which can harm the systemic organs.

- Inflammation and Formation of pseudomembrane
- Damages to organs.

Laboratory Identification:
1. Culture
-> Tinsdale Agar: selective and differential
2. Detection of toxin
- PCR: indicated presence of toxin genes.
- Elk Test: demonstrates toxin production

Front 287

Describe Haemophilus Influenzae:

Back 287

1. Normal component of the upper respiratory tract infection.
2. Type B (capsule) associated with disease.

Pathogenesis:
- Pili
- Non-pilus adhesins (i.e. P2)
- LPS: impairs ciliary function
- Antiphagoctyic Capsule composed of Polyrobose Ribitol Phosphate (PPP).
- IgA Proteases

Prevention:
- Hib = Haemophilus Influenzae Type B.
- Immunity is correlated with presence of antibodies against PRP capsule
- Vaccine composed of PRP coupled to a protein carrier.
- Mediates T-Cell Depndent Response
- Immune Response in Children as young as 2.

Front 288

Bordetella Pertussis

Back 288

Causes Whooping Cough.

Highly Communicable / Very infectious via aerosols.

~90% of exposed susceptible individuals become infected.

Pathogenesis:
Filamentous Haemagglutenin Toxin:
-> Protein, agglutinated red blood cells.
-> Attaches to Galactose-N-acetylglucosamine residues of host cell glycolipids.
-> Attaches to Ciliated epithelia of bronchi and trachea vis pili.

Look at page 27-32/23 for details on toxins.

Culture: (100% specific)
- Charcoal Blood agar containing a cephalosporin
- Characteristic Colonies after 3-7 days.

Prevention: Part of a DaTp accine ("aP") - acellular pertusiss

Vaccines:
1.Whole Cell (Formalyin Inactivated).
2. Inactivated PT + Acellular components, e.g. Fha, PT.
3. Immunity (vaccine - or infection-derived) can decrease over time -> booster shots are necessary.

Front 289

Klebsiella Pneumonia

Back 289

- Causes: Necrotization (absess formation) of lungs
- It is part of Microbial Flora
- Gram -ve Bacteria
- Cause a "redcurrant jelly" sputum
- Causes SEVERE and DESTRUCTIVE nosocomial pneumonia.

Front 290

Describe Legionella Pneumophila:

Back 290

1. Legionaire's Disease (pneumonia)
2. Pontiac Fever (Milder Form)
3. Risk: Immunocompramised, Elderly, males, smokers.

Epidimiiology:
- freshwater enviornment
- sequestered in biofilms
- Exposure is by air/aerosols
- Capable of survivial in water treatment and 63 C.
- Person to Person transmission is rare.

Front 291

What is the pathogenesis if legionalla Pneumophilia?

Back 291

1. It gets uptaken by macrophages and prevents phagosome acidification. Blocking phagosome-lysosome fusion.

Most of the damage occurs by host inflammatory response.

Front 292

Describe some of the background on Tuberculosis:

Back 292

It is one of the top 3 killers world-wide.

It is an acid-fast bacilli, grow in long parallel chains and it is aerobic.

Medically important species:
- M. Tuberculosis. M.Bovis, M.Avium.

Front 293

Describe the structural components of TB:

Back 293

1. Peptodpglycan: Similar to Gram Positive Bacteria: NAM and NAG via tetrapeptide.

2. Lipid-Rich: Mycolic Acids
- they slow growth and formation of clumps and cords
- resistant to detergents
- Hydrophobicity
- Extended Survivial

3. Lipoarabinomannan (LAM)
- Structually and functionally similar to O-antigenic LPS and other bacteria.
Activities:
- Induce cytokine production by macrophage.
- Suppress T-cell prolifiration
- Inhibit Interferon-gamma-Activation of macrophages.
- Interaction with dendritic cells to enable uptake/entry.

Front 294

What is the epidimiology of TB?

Back 294

- Minimum Infectious Dose: 10 bacilli
- Defects in cell-mediated immunity will elevate the risk of developing TB to either:
- Exogenous Infection
- Endogenous reactivation

Immunosupressed (HIV) have increased risk of developing TB.

Front 295

What is the Pathogenesis of TB?

Back 295

Interacellular Survivial in Alveolar Macrophages:
1. Prevent oxidative burst and inhibit phagosome-lysosome fusion
2. Resist Lysosomal enzymes, reactive oxygen species
-> Cell wall lipids, LAM, secretion of superoxide dismutasse.
3. Escape Phagosome -> Cytoplasm
4. Iron aquisition through siderphore production.

Front 296

How do you identifiy TB in the lab?

Back 296

Culture Requires Enriched Medium:
- Lowenstein-Jensen agar
- Oleic Acid - albumin broth.

Antimicrobial susceptability testing is increasing needed because of multiple drug resistant strains (MDR).

Microscopy of Sputum: Ziehl-Neelsen or Rhodamine-Auramine Flourescence test.

Confirmation: PPD/Mantoux/Tuberculin tests.

- 5 mm = HIV/Immunosupressed
- 10 mm = health care workers
- 15 mm = individuals with no risk factors.

Vaccination: BCG (M.bovis) but it is somewhat controversial.

Front 297

In the enviornment fungi are: and in the tissues they are?

Back 297

Enviornment: MOLDS
Tissue: Yeasts

Front 298

What are the key stages in pathogenesis of yeasts?

Back 298

1. Be inhaled and reach terminal bronchi/alveoli
2. Convert to form capable of replication at 37C.
3. Usually Mycelial - > Yeast
(enhances survival because yeasts are not killed as easily by Macrophages)
4. Colonize the respiratory tract.

Front 299

How do you diagnose primary and opportunistic fungal pathogens?

Back 299

1. Sputum
2. BAL
3. Transtrachial Aspirate
4. Lung Biopsy

Techniques:
1. Direct Microscopy
2. Culture on appropriate media
3. Nucleic Acid Probes
4. Fixed Speciment: Giemsa Stain, PAS, GMS, indirect FA stain, DFA, etc.

Front 300

Describe what is special about.
1. H Capsulatum
2. D. Dermatidis
3. C. Immitis

Back 300

1. Large thick walled oval narrow-based budding yeasts
2. Thick walled broad-based budding yeasts.
3. Thick walled spherule with multiple endospores.

Front 301

Delayed Hypersensitivity test can be used for which which type of Fungi? What are the specific antigens that can be used?

Back 301

1. Coccidioides
Two antigens can be used:
i. Coccidioidin - Mycelial Phase Antigen
ii. Spherulin - Spherule phase antigen.

Front 302

What fungi would you do an Ex-antigen Tests?

Back 302

You can do it for Coccidioidomycosis and Blastomycosis:
i. Basis: Immunodiffusion
ii. Detects antibody using cell free antigens produced during mycelial growth.
iii. Good specificity when used with appropriate antiserum.

Front 303

What is Histoplasmosis Caosulatum, What is the main disease and what are the disease for the var. capsulatum and var duboissi?

Back 303

1. Main Syndrome - Darling's Disease
2. H. Capsulatum var. Capsulatum - Pulminary and Dissimainated Disease.
3. H. Capsulatum var. Duboisi causes Skin and Bone lesions, more common then pulmonary manifestations.

Front 304

Describe the epidimilogy of Histoplasama Capsulatum?

Back 304

1. Saprophyte in moist, rich soils with high nitrogen content. Outbreaks are associated with those areas.

Front 305

What is the pathogenesis of H. Capsulatum and Histoplasmosis?

Back 305

1. It is close to TB.
-It is a faculatative intracellular pathogen in macrophage.
- Infection by inhalation
- Can dissiminate via liver, spleen (mononuclear phagocytic system).
- Infection contained by cell-mediated immune response
- Can detect using skin tests for DTHR
- Persistent subclinical infection with subsequent reactivation.

Front 306

Describe Blastomyces Dermatitis:

Back 306

Similar to Histoplasmosis in terms of distribution.

Outcomes.
1. Cutaneous Infection
-> Can either be primary or secondary.
2. Systemic
Multiple forms:
- Subclinical
- Pulmonary "flu-like"
- Chronic Pneumonia
- Systemic Illness

The pattern of infection:
1. Subclinical
2. Acute Pneumonia
3. Chronic Pneumonia
4. Disseminated Infection

Front 307

Describe Coccidioides Species:

Back 307

1. It causes Coccidiodomycosis ("Valley Fever", San Joaquin Fever").
2. Located in Arid and Semi-Arid soilds.
3. Highest exposure in late summer/early fall (dusty conditions) and in dry seasons preceded by heavy rainfaill.

Front 308

What is the pathogenesis of Coccidiodides Species?

Back 308

1. Inhalation of arthroconidia -> Primary coccidiodomycosis. Once inhaled, arthrocondia convert to characteristic large spherule: Size o spheres (20-50 um) prevent phagocytosis. Filled with a few up-to hundreds of 2-4 um endospores.

Outcomes:
1. Asymptomatic/Mild illness
2. Symptomatic: flu-like illness (40%)

Mostly self-limiting. Can occasionally progress to:
- Chronic Fibrocavitary Disease.
- Disseminated Disease: any tissue/organ, including skin, bone, meninges.

Recovery and specific protecting strongly depended on specific T-lymphocyte response.

Front 309

Describe the general trend with opportunistic fungal pathogens:

Back 309

1. Monomorphic.
2. Acquired via inhilation from enviornment
3. Important cause of invasive/disseminated mycoses in immunocompramised individuals.
4. Increasing in frequency in terms of incidence in the population. Related to increase in numbers of "at-risk" individuals.

Front 310

Describe Cryptococcus Neoformans (opportinistic).

Back 310

Encapsulated Yeast in tissue.
MOST COMMON FUNGUL INFECTION IN AIDS PATIENTS.

Pathogenesis:
Inhalation of unencapsulated yeast into alveoli triggers the production of capsule.

Composition: glucoronoxylomannan (GXM)
Capsule detectedable in blood and fluids: seems to down-regulate the immune response.

Cryptococci have strong affinity for CNS (neurotropic).
Can oxidize exogenous catecholamines -> melanin: prevents fungi from down-regulate the immune response.

Cryptococci have a strong affinity for CNS (neurotropic).

Can oxidize exogenous catecholamines -> melanin: prevents fungi from phagocytotyic oxidative damage.

Front 311

Describe Pnemocystic Jiroveci:

Back 311

Key Syndrome: Pneumocystic Pneomonia (PCP).

Unusual fungus: lacks ergosterol cell wall. Initially thought to be a protoxoan. Difficult to grow in culture.

Most common serious opportunistic illness in HIV infected individuals.

Front 312

Describe Aspergillis SP?

Back 312

Found in decaying matter air, and soil.

Outcomes of infection/Exposure:
1. Allergic asperillosis
2. Invasive aspergillosis: hyphae invade tissue.

Can get formation of "fungal ball" usually in pre-existing lung cavity.

Front 313

Describe Hantavirus (Emerging Respirtaory Tract Pathogen)

Back 313

Key Syndrome: Hantavirus Pulmonary Syndrome (HPS)
Fulminant Resporatory Disease outbreak in 1993.
Severe pulmonary distress, pneumonia.

High mortality rate: 50-75%

Family: Bunyaviridae

ss(-) RNA, 3 segments, S, M, L

Reservoir = long tail Pygmy rice rats (chile), rats and mice.

HUMAN infection occurs due to inhalation of Excreta.

Front 314

What does metapneumovirus (MPv) Cause?

Back 314

Bronchilities.

RT-PCR is necessary for diagnosis and differentiation.