Fa: Microbiology - Basic Bacteriology

Front 1

What is the function of Peptidoglycan? Chemical composition?

Back 1

- Gives rigid support and protects against osmotic pressure
- Sugar backbone with peptide side chains cross-linked by transpeptidase

Front 2

What is the function of Cell Wall / Cell Membrane (which kind of bacteria have this)? Chemical composition?

Back 2

Gram Positives
- Major surface antigen
- Made of peptidoglycan for support
- Lipoteichoic acid induces TNF and IL-1

Front 3

What is the function of Outer Membrane (which kind of bacteria have this)? Chemical composition?

Back 3

- Gram Negatives
- Site of endotoxin (LPS) - major surface antigen
- Lipid A induces TNF and IL-1
- O-polysaccharide is the antigen

Front 4

What is the function of the Plasma Membrane in bacteria? Chemical composition?

Back 4

- Site of oxidative and transport enzymes
- Phospholipid bilayer

Front 5

What is the function of ribosomes? Chemical composition?

Back 5

- Protein synthesis
- 50S and 30S subunits

Front 6

What is the function of the Periplasm? Chemical composition?

Back 6

- Space between the cytoplasmic membrane and outer membrane in gram-negative bacteria
- Contains many hydrolytic enzymes, including β-lactamases

Front 7

What is the function of the bacterial capsule? Chemical composition?

Back 7

- Protects against phagocytosis
- Polysaccharide (except Bacillus anthracis, which contains D-glutamate)

Front 8

What is the function of the pilus/fimbria? Chemical composition?

Back 8

- Mediates adherence of bacteria to cell surface
- Sex pilus forms attachment between 2 bacteria during conjugation
- Made of glycoprotein

Front 9

What is the function of flagella? Chemical composition?

Back 9

- Motility
- Made of proteins

Front 10

What is the function of Spores? Chemical composition?

Back 10

- Resistant to dehydration, heat, and chemicals
- Keratin-like coat; dipicolinic acid; peptidoglycan

Front 11

What is the function of Plasmids? Chemical composition?

Back 11

- Contains a variety of genes for antibiotic resistance, enzymes, and toxins
- Made of DNA

Front 12

What is the function of Glycocalyx? Chemical composition?

Back 12

- Mediates adherence to surfaces, especially foreign surfaces (eg, indwelling catheters)
- Made of polysaccharide

Front 13

What are the different morphologies of bacteria?

Back 13

- Circular (coccus)
- Rod (bacillus)
- Branching filamentous
- Pleomorphic
- Spiral
- No cell wall

Front 14

What are some G+ cocci? G-?

Back 14

G+
- Staphylococcus
- Streptococcus

G-
- Neisseria

Front 15

What are some G+ rods / bacilli?

Back 15

- Clostridium
- Corynebacterium
- Bacillus
- Listeria
- Mycobacterium (acid fast)
- Gardnerella (gram variable)

Front 16

What are the types of G- rods / bacilli?

Back 16

- Enterics
- Respiratory
- Zoonotic

Front 17

What are the Enteric G- rods / bacilli?

Back 17

- E. coli
- Shigella
- Salmonella
- Yersinia
- Klebsiella
- Proteus
- Enterobacter
- Serratia
- Vibrio
- Campylobacter
- Helicobacter
- Pseudomonas
- Bacteroides

Front 18

What are the Respiratory G- rods / bacilli?

Back 18

- Haemophilus (pleomorphic)
- Legionella (silver)
- Bordetella

Front 19

What are the Zoonotic G- rods / bacilli?

Back 19

- Francisella
- Brucella
- Pasteurella
- Bartonella

Front 20

What are the branching filamentous G+?

Back 20

- Actinomyces
- Nocardia (weakly acid fast)

Front 21

What are the Pleomorphic G-?

Back 21

- Rickettsiae (Giemsa)
- Chlamydiae (Giemsa)

Front 22

What are the Spiral G-?

Back 22

Spirochetes:
- Borrelia (Giemsa)
- Leptospira
- Treponema

Front 23

What are the bacteria with no cell wall (do not gram stain)?

Back 23

Mycoplasma

Front 24

What is unusual about the cell membranes / walls of Mycoplasma?

Back 24

Contain sterols and have no cell wall

Front 25

What is unusual about the cell membranes / walls of Mycobacteria?

Back 25

Contain mycolic acid; high lipid content

Front 26

Which bugs do not gram stain well?

Back 26

These Microbes May Lack Real Color:
- Treponema (too thin to be visualized)
- Mycobacteria
- Mycoplasma (no cell wall)
- Legionella pneumophila (primarily intracellular)
- Rickettsia (intracellular parasite)
- Chlamydia (intracellular parasite, lacks muramic acid in cell wall)

Front 27

How can you visualize Treponema bacteria (causes syphilis)?

Back 27

- Use dark-field microscopy and fluorescent antibody staining
- It is too thin to be visualized with Gram stain

Front 28

How can you visualize Mycobacteria (causes TB)?

Back 28

- Carbolfuchsin in acid-fast stain detects the high lipid content in cell wall
- Does not Gram stain well

Front 29

How can you visualize Legionella?

Back 29

- Silver stain
- Does not Gram stain well

Front 30

Which bacteria can be stained with the Giemsa stain?

Back 30

Certain Bugs Really Try my Patience:
- Chlamydia
- Borrelia
- Rickettsiae
- TRYpanosomes
- Plasmodium

Front 31

What does the PAS (periodic acid-Schiff) stain, stain? Use?

Back 31

PASs the SUGAR:
- Stains glycogen, mucopolysaccharides
- Used to diagnose Whipple disease (Tropheryma whipplei)

Front 32

Which bacteria can be stained with the Ziehl-Neelsen (Carbol Fuchsin) stain?

Back 32

Acid fast organisms
- Nocardia
- Mycobacterium

Front 33

Which microbe can be stained with the India Ink stain?

Back 33

Cryptococcus neoformans (mucicarmine can also be used to stain thick polysaccharide capsule red)

Front 34

Which microbes can be stained with the Silver stain?

Back 34

- Fungi (eg, Pneumocystis)
- Legionella
- Helicobacter pylori

Front 35

What are the special culture requirements of H. influenzae?

Back 35

Chocolate agar w/ factors V (NAD+) and X (Hematin)

Front 36

What are the special culture requirements of N. gonorrhoeae and N. meningitidis?

Back 36

Thayer-Martin (or VPN) media
- Vancomycin (inhibits G+ organisms)
- Polymyxin (inhibits G- organisms except Neisseria)
- Nystatin (inhibits fungi)

"To connect to Neisseria, please use your VPN client"

Front 37

What are the special culture requirements of B. pertussis?

Back 37

Bordet-Gengou (potato) agar
(Bordet for Bordetella)

Front 38

What are the special culture requirements of C. diphtheriae?

Back 38

- Tellurite agar
- Löffler medium

Front 39

What are the special culture requirements of M. tuberculosis?

Back 39

Löwenstein-Jensen agar

Front 40

What are the special culture requirements of M. pneumoniae?

Back 40

- Eaton agar
- Requires cholesterol

Front 41

What are the special culture requirements of Lactose-Fermenting enterics?

Back 41

- MacConkey agar (fermentation produces acid, turning the colony PINK)
- E. coli is also grown on eosin-methylene blue (EMB) agar as colonies with green metallic sheen

Front 42

What are the special culture requirements of Legionella?

Back 42

Charcoal yeast extract agar buffered with cysteine and iron

Front 43

What are the special culture requirements of Fungi?

Back 43

SABouraud agar = "SAB's a fun guy"

Front 44

What are the requirements of Obligate Aerobes?

Back 44

Use an O2-dependent system to generate ATP

Front 45

Which kind of bacteria use an O2-dependent system to generate ATP?

Back 45

Obligate Aerobes: Nagging Pests Must Breathe
- Nocardia
- Pseudomonas
- MycoBacterium tuberculosis

Front 46

What is the relationship of Pseudomonas to O2? Where does it infect?

Back 46

P. aeruginosa in an obligate aerobe seen in burn wounds, complications of diabetes, nosocomial pneumonia, and pneumonias in cystic fibrosis patients

Front 47

What is the relationship of Mycobacterium tuberculosis to O2? Where does it infect?

Back 47

Obligate Aerobe
- Reactivation has a predilection for the apices of the lung (which have the highest PO2)
- Reactivation may occur after immune compromise or TNF-α inhibitor use

Front 48

What are the requirements of Obligate Anaerobes?

Back 48

Anaerobes Can't Breathe Air

Front 49

Which kind of bacteria can not be exposed to oxygen? Where are they found?

Back 49

Obligate Anaerobes: Can't Breathe Air
- Clostridium
- Bacteroides
- Actinomyces

Anaerobes are normal flora in the GI tract, pathogenic elsewhere

Front 50

What are the characteristics of Clostridium, Bacteroides, and Actinomyces?

Back 50

Obligate Anaerobes
- Lack catalase and/or superoxide dismutase and thus are susceptible to oxidative damage
- Generally foul smelling (short-chain FAs)
- Difficult to culture
- Produce gas in tissue (CO2 and H2)
- Normally found in GI tract, pathogenic elsewhere

Front 51

Which antibiotics are ineffective against Obligate Anaerobes? Why?

Back 51

AminO2glycosides:
- Ineffective against anaerobes because these antibiotics require O2 to enter into bacterial cell
- Obligate Anaerobes only are grow in areas without O2

Front 52

What are the obligate intracellular bugs?

Back 52

Stay inside (cells) when it is Really Cold:
- Rickettsia
- Chlamydia

Front 53

What are the facultative intracellular bugs?

Back 53

Some Nasty Bugs May Live FacultativeLY
- Salmonella
- Neisseria
- Brucella
- Mycobacterium
- Listeria
- Francisella
- Legionalla
- Yersinia pestis

Front 54

What are the encapsulated bacteria?

Back 54

SHiNE SKiS
- Streptococcus pneumoniae
- Haemophilis Influenzae type B
- Neisseria meningitidis
- Escherichia coli
- Salmonella
- Klebsiella pneumoniae
- Strep group B

Front 55

What is the function of the capsule on:
SHiNE SKiS
- Streptococcus pneumoniae
- Haemophilis Influenzae type B
- Neisseria meningitidis
- Escherichia coli
- Salmonella
- Klebsiella pneumoniae
- Strep group B

Back 55

- Capsules act as an anti-phagocytic virulence factor
- Capsule + protein conjugate serves as an antigen in vaccines

Front 56

How do hosts clear encapsulated bacteria?

Back 56

- Opsonize bacteria and then cleared by spleen
- Asplenics have decreased opsonizing ability and are at risk for severe infections (give S. pneumoniae, H. influenzae, and N. meningitidis vaccines)

Front 57

What vaccines should asplenics get in particular? Why?

Back 57

- Asplenics have decreased opsonizing ability and are at risk for severe infections (give S. pneumoniae, H. influenzae, and N. meningitidis vaccines = encapsulated bacteria)
- Opsonization and clearance by spleen is the method of hosts to remove encapsulated bacteria

Front 58

What are the Catalase-Positive organisms?

Back 58

You need PLACESS for your CATs
- Pseudomonas
- Listeria
- Aspergillus
- Candida
- E. coli
- S. aureus
- Serratia

Front 59

What is the action of catalase?

Back 59

Degrades H2O2 before it can be converted to microbicidal products by the enzyme myeloperoxidase (protective mechanism)

Front 60

What is wrong with patients with chronic granulomatous disease?

Back 60

They have a deficiency of NADPH oxidase
- This enzyme generates superoxide for neutrophils to fight infection

These patients are at increased susceptibility to recurrent infections with Catalase (+) organisms because this enzyme degrades H2O2 (another ROS)

Front 61

What vaccines are available for encapsulated bacteria?

Back 61

Pneumococcal vaccines:
- PCV: Pneumococcal Conjugate Vaccine
- PPSV: Pneumococcal Polysaccharide Vaccine with no conjugated protein

H. Influenzae type B (conjugate vaccine)

Meningococcal vaccine (conjugate vaccine)

Front 62

What are the characteristics of vaccines made for encapsulated bacteria (Pneumococcal, H. influenzae type B, Meningococcal)?

Back 62

Some vaccines containing polysaccharide capsule antigens are conjugated to a carrier protein, enhancing immunogenicity by promoting T-cell activation and subsequent class switching

Front 63

What are the urease positive bugs?

Back 63

CHuck norris hates PUNKSS
- Cryptococcus
- H. pylori
- Proteus
- Ureaplasma
- Nocardia
- Klebsiella
- S. epidermidis
- S. saprophyticus

Front 64

What are the pigment producing bacteria?

Back 64

- Actinomyces israelii = yellow granules
- S. aureus = yellow pigment
- Pseudomonas aeruginosa = blue-green pigment
- Serratia marcescens = red pigment

Front 65

Which bacteria makes yellow "sulfur" granules, composed of filaments of bacteria?

Back 65

Actinomyces israelii
(Israel has yellow sand)

Front 66

Which bacteria makes yellow pigment?

Back 66

S. aureus
(aureus = gold in Latin)

Front 67

Which bacteria makes blue-green pigment?

Back 67

Pseudomonas aeruginosa
(Aerugula is green)

Front 68

Which bacteria makes a red pigment?

Back 68

Serratia marcescens
(think red maraschino cherries)

Front 69

What is the function of bacterial virulence factors? Examples?

Back 69

Promotes evasion of host immune response
- Protein A
- IgA Protease
- M Protein

Front 70

What is the function of "Protein A"? Which bacteria express(es) this?

Back 70

Bacterial virulence factor
- Binds Fc region of IgG
- Prevents opsonization and phagocytosis
- Expressed by S. aureus

Front 71

What is the function of "IgA Protease"? Which bacteria expresses this?

Back 71

Bacterial virulence factor
- Enzyme that cleaves IgA
- Secreted by S. pneumoniae, H. influenzae type B, and Nesseria (SHiN) in order to colonize the respiratory mucosa

Front 72

What is the function of "M Protein"? Which bacteria expresses this?

Back 72

Bacterial virulence factor
- Helps prevent phagocytosis
- Expressed by group A streptococci

Front 73

Which bacterial virulence factor helps prevent phagocytosis of group A streptococci?

Back 73

M protein

Front 74

Which bacterial virulence factor helps prevent opsonization and phagocytosis of S. aureus by binding the Fc region of IgG?

Back 74

Protein A

Front 75

Which bacterial virulence factor cleaves IgA? Which bacteria have this virulence factor?

Back 75

IgA Protease
- Secreted by S. pneumoniae, H. influenzae type B, and Nesseria (SHiN) in order to colonize the respiratory mucosa

Front 76

What is the source of Exotoxins vs. Endotoxins?

Back 76

- Exotoxin: certain species of G+ and G- bacteria
- Endotoxin: outer cell membrane of most G- bacteria

Front 77

Are Exotoxins and/or Endotoxins secreted from cells?

Back 77

- Exotoxin: secreted from cells
- Endotoxin: not secreted

Front 78

What is the structure/chemistry of Exotoxins vs. Endotoxins?

Back 78

- Exotoxin: polypeptide
- Endotoxin: lipopolysaccharide (structural part of bacteria; released when lysed)

Front 79

What is the location of genes of Exotoxins vs. Endotoxins?

Back 79

- Exotoxin: plasmid or bacteriophage
- Endotoxin: bacterial chromosome

Front 80

What is the relative toxicity of Exotoxins vs. Endotoxins?

Back 80

- Exotoxin: high (fatal dose on the order of 1 µg)
- Endotoxin: low (fatal dose on the order of hundreds of µgs)

Front 81

What are the clinical effects of Exotoxins vs. Endotoxins?

Back 81

- Exotoxin: various effects
- Endotoxin: fever, shock (hypotension), DIC

Front 82

What is the mode of action of Exotoxins vs. Endotoxins?

Back 82

- Exotoxin: various modes
- Endotoxin: induces TNF, IL-1, and IL-6

Front 83

What is the antigenicity of Exotoxins vs. Endotoxins?

Back 83

- Exotoxin: induces high-titer antibodies called antitoxins
- Endotoxin: poorly antigenic

Front 84

Are there vaccines for Exotoxins vs. Endotoxins?

Back 84

- Exotoxin: toxoids used as vaccines
- Endotoxin: no toxoids formed and no vaccine available

Front 85

What is the relative heat stability of Exotoxins vs. Endotoxins?

Back 85

- Exotoxin: destroyed rapidly at 60 degrees C (except staphylococcal enterotoxin)
- Endotoxin: stable at 100 degrees C for 1 hr

Front 86

What are the typical diseases associated with Exotoxins vs. Endotoxins?

Back 86

- Exotoxin: tetanus, botulism, diphtheria
- Endotoxin: meningococcemia, sepsis by G- rods

Front 87

Exotoxins
1) Source?
2) Secreted?
3) Chemistry?
4) Location of genes?
5) Toxicity?
6) Clinical effects?
7) Mode of action?
8) Antigenicity?
9) Vaccines?
10) Heat stability?
11) Typical diseases?

Back 87

1) Source: certain species of G+ and G- bacteria
2) Secreted: yes
3) Chemistry: polypeptide
4) Location of genes: plasmid or bacteriophage
5) Toxicity: high (fatal dose on order of 1 µg)
6) Clinical effects: varies
7) Mode of action: varies
8) Antigenicity: induces high-titer antibodies called antitoxins
9) Vaccines: toxoids used as vaccines
10) Heat stability: destroyed rapidly at 60 degrees C (except staphylococcal entertoxin)
11) Typical diseases: tetanus, botulism, diphtheria

Front 88

Endotoxins
1) Source?
2) Secreted?
3) Chemistry?
4) Location of genes?
5) Toxicity?
6) Clinical effects?
7) Mode of action?
8) Antigenicity?
9) Vaccines?
10) Heat stability?
11) Typical diseases?

Back 88

1) Source: outer cell membrane of most G- bacteria
2) Secreted: no
3) Chemistry: lipopolysaccharide (structural part of bacteria; released when lysed)
4) Location of genes: bacterial chromosome
5) Toxicity: low (fatal dose on order of hundreds of µgs)
6) Clinical effects: fever, shock (hypotension), DIC
7) Mode of action: induces TNF, IL-1, IL-6
8) Antigenicity: poorly antigenic
9) Vaccines: no toxoids formed and no vaccine available
10) Heat stability: stable at 100 degrees C for 1 hrs
11) Typical diseases: meningococcemia, sepsis by G- rods

Front 89

What are some possible mechanisms of exotoxins?

Back 89

- Inhibit protein synthesis
- Increase fluid secretion
- Inhibit phagocytic ability
- Inhibit release of NT
- Lyse cell membranes
- Superantigens causing shock

Front 90

What are the characteristics of an ADP ribosylating A-B toxin?

Back 90

- B (binding) component binds to host cell surface receptor
- A (active) component attaches ADP-ribosyl to disrupt host cell proteins

Front 91

Which bacteria release exotoxins that inhibit protein synthesis?

Back 91

- Corynebacterium diphtheriae
- Pseudomonas aeruginosa
- Shigella spp.
- Enterohemorrhagic E. coli (EHEC), including O157:H7 strain

Front 92

Corynebacterium diphtheriae exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 92

1) Toxin: Diphtheria toxin (ADP ribosylating A-B toxin)
2) Mechanism: inactivates elongation factor (EF-2) which inhibits protein synthesis
3) Manifestation: pharyngitis with pseudomembranes in throat and severe lymphadenopathy (bull neck)

Front 93

Pseudomonas aeruginosa exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 93

1) Toxin: Exotoxin A (ADP ribosylating A-B toxin)
2) Mechanism: inactivates elongation factor (EF-2) which inhibits protein synthesis
3) Manifestation: host cell death

Front 94

Shigella spp. exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 94

1) Toxin: Shiga Toxin (ST) - (ADP ribosylating A-B toxin)
2) Mechanism: inactivates 60S ribosome by removing adenine from rRNA, which inhibits protein synthesis
3) Manifestation: GI mucosa damage → dysentery; also enhances cytokine release, causing Hemolytic Uremic Syndrome (HUS)

Front 95

Enterohemorrhagic E. coli (EHEC) exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 95

1) Toxin: Shiga-LIKE toxin (SLT) - (ADP ribosylating A-B toxin)
2) Mechanism:inactivates 60S ribosome by removing adenine from rRNA, which inhibits protein synthesis (same as Shiga Toxin)
3) Manifestation: enhances cytokine release, causing Hemolytic Uremic Syndrome (HUS); but does not invade host cells

Front 96

Which bacteria release exotoxins that increase fluid secretion?

Back 96

- Enterotoxigenic E. coli (ETEC)
- Bacillus anthracis
- Vibrio cholerae

Front 97

Enterotoxigenic E. coli (ETEC) exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 97

1) Toxin: Heat-LABILE toxin (LT) - (ADP ribosylating A-B toxin)
2) Mechanism: overactivates AC → ↑cAMP → ↑Cl- secretion in gut and H2O efflux (same as cholera toxin)

1) Toxin: Heat-STABLE toxin (ST)
2) Mechanism: overactivates GC → ↑cGMP → ↓ resorption of NaCl and H2O in gut

3) Manifestation: watery diarrhea - labile in the Air (AC) but stable on the Ground (GC)

Front 98

Bacillus anthracis exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 98

1) Toxin: edema factor
2) Mechanism: mimics AC enzyme → ↑cAMP
3) Manifestation: likely responsible for characteristic edematous borders of black eschar in cutaneous anthrax

Front 99

Vibrio cholerae exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 99

1) Toxin: cholera toxin - (ADP ribosylating A-B toxin)
2) Mechanism: overactivates Gs → ↑AC → ↑cAMP → ↑Cl- secretion in gut and H2O efflux (same as heat labile toxin of ETEC)
3) Manifestation: voluminous "rice-water" diarrhea

Front 100

Which bacteria release exotoxins that inhibit phagocytic ability?

Back 100

Bordetella pertussis

Front 101

Bordetella pertussis exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 101

1) Toxin: Pertussis toxin - (ADP ribosylating A-B toxin)
2) Mechanism: disables Gi → overactivates AC → ↑cAMP → impairs phagocytosis to permit survival of microbe
3) Manifestation: Whooping Cough (child coughs on expiration and "whoops" on inspiration - toxin may not actually be a cause of cough but can cause the 100 day cough in adults)

Front 102

Which bacteria release exotoxins that inhibit release of NT?

Back 102

- Clostridium tetani
- Clostridium botulinum

Front 103

Clostridium tetani exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 103

1) Toxin: Tetanospasmin
2) Mechanism: protease that cleaves SNARE proteins → prevents release of inhibitory (GABA and glycine) NTs from Renshaw cells in spinal cord
3) Manifestation: spasticity, risus sardonicus, and "lockjaw"

Front 104

Clostridium botulinum exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 104

1) Toxin: Botulinum toxin
2) Mechanism: protease that cleaves SNARE proteins → prevents release of stimulatory (ACh) signals at neuromuscular junctions
3) Manifestation: flaccid paralysis, floppy baby

Front 105

Which bacteria release exotoxins that lyse cell membranes?

Back 105

- Clostridium perfringens
- Streptococcus pyogenes

Front 106

Clostridium perfringens exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 106

1) Toxin: alpha toxin
2) Mechanism: phospholipase (lecithinase) that degrades tissue and cell membranes
3) Manifestation: degrades phospholipids → myonecrosis ("gas gangrene") and hemolysis ("double zone" of hemolysis on blood agar)

Front 107

Streptococcus pyogenes exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 107

1) Toxin: Streptolysin O
2) Mechanism: protein that degrades cell membrane
3) Manifestation: lyses RBCs, contributes to β-hemolysis; host antibodies against toxin (ASO) used to diagnose rheumatic fever (do not confuse w/ immune complexes of poststreptococcal glomerulonephritis)

1) Toxin: Exotoxin A
2) Mechanism: bring MHC II and TCR in proximity to outside of antigen binding site to cause overwhelming release of IFN-γ and IL-2 → shock
3) Manifestation: toxic shock syndrome - fever, rash, shock

Front 108

Which bacteria release exotoxins that are superantigens causing shock?

Back 108

- Staphylococcus aureus
- Streptococcus pyogenes

Front 109

Staphylococcus aureus exotoxin:
1) Toxin
2) Mechanism
3) Manifestation

Back 109

1) Toxin: Toxic Shock Syndrome Toxin (TSST-1)
2) Mechanism: bring MHC II and TCR in proximity to outside of antigen binding site to cause overwhelming release of IFN-γ and IL-2 → shock
3) Manifestation: toxic shock syndrome - fever, rash, shock, other toxins cause scalded skin syndrome (exfoliative toxin) and food poisoning (enterotoxin)

Front 110

Which bacteria have endotoxins? Structure?

Back 110

LPS found in outer membrane of G- bacteria (both cocci and rods)

Front 111

What is the mnemonic to remember traits of Endotoxin?

Back 111

ENDOTOXIN:
- Edema
- Nitric oxide
- DIC / Death
- Outer membrane
- TNF-α
- O-antigen
- eXtremely heat stable
- IL-1
- Neutrophil chemotaxis

Front 112

What are the actions of Endotoxin (especially Lipid A)?

Back 112

- Activates macrophages
- Activates complement
- Activates tissue factor

Front 113

What are the effects of activated macrophages following endotoxin synthesis (especially Lipid A)?

Back 113

- IL-1 → Fever
- TNF → Fever and hypotension
- Nitric Oxide → hypotension

Front 114

What are the effects of activated complement following endotoxin synthesis (especially Lipid A)?

Back 114

- C3a → hypotension and edema
- C5a → neutrophil chemotaxis

Front 115

What are the effects of activated tissue factor following endotoxin synthesis (especially Lipid A)?

Back 115

Coagulation cascade → DIC

Front 116

What are the mechanisms of exchanging genetic material between bacteria?

Back 116

- Transformation
- Conjugation
- Transposition
- Transduction

Front 117

What is Transformation?

Back 117

Ability to take up naked DNA (ie, from cell lysis) from environment (aka "competenence")

Front 118

What is the term for the ability to take up naked DNA (ie, from cell lysis) from environment (aka "competenence")? Which bacteria is this a feature of?

Back 118

Transformation
- S. pneumoniae, H. influenzae type B, and Nesseria (SHiN)
- Any DNA can be used
- Adding deoxyribonuclease to environment will degrade naked DNA in medium → no transformation seen

Front 119

What is Conjugation?

Back 119

Two types:

F+ x F-
- F+ plasmid contains genes required for sex pilus and conjugation
- Bacteria without plasmid are termed F-
- Plasmid (dsDNA) is replicated and transferred through pilus from F+ cell
- No transfer of chromosomal genes

Hfr x F-
- F+ plasmid can become incorporated into bacterial chromosomal DNA, termed high frequency recombination (Hfr) cell
- Replication of incorporated plasmid DNA may include some flanking chromosomal DNA
- Transfer of plasmid and chromosomal genes

Front 120

What is F+ x F- conjugation?

Back 120

- F+ plasmid contains genes required for sex pilus and conjugation
- Bacteria without plasmid are termed F-
- Plasmid (dsDNA) is replicated and transferred through pilus from F+ cell
- No transfer of chromosomal genes

Front 121

What is Hfr x F- conjugation?

Back 121

- F+ plasmid can become incorporated into bacterial chromosomal DNA, termed high frequency recombination (Hfr) cell
- Replication of incorporated plasmid DNA may include some flanking chromosomal DNA
- Transfer of plasmid and chromosomal genes

Front 122

What is Transposition?

Back 122

- Segment of DNA (eg, transposon) that can "jump" (excision and reintegration) from one location to another
- Can transfer genes from plasmid to chromosome and vice versa
- When excision occurs, may include some flanking chromosomal DNA which can be incorporated into a plasmid and transferred to another bacterium
- Eg: antibiotic resistance on R plasmid

Front 123

What happens in Generalized Transduction?

Back 123

- PACKAGING event
- Lytic phage infects bacterium
- Leads to cleavage of bacterial DNA
- Parts of bacterial chromosomal DNA may become packed in viral capsid
- Phage infects another bacterium, transferring these genes

Front 124

What happens in Specialized Transduction?

Back 124

- EXCISION event
- Lysogenic phage infects bacterium
- Viral DNA incorporates into bacterial chromosome
- When phage DNA is excised, flanking bacterial genes may be excised with it
- DNA is packaged into phage viral capsid and can infect another bacterium

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Which toxins are encoded in a lysogenic phage (specialized transduction)?

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ABCDE:
- shigA-like toxin
- Botulinum toxin (certain strains)
- Cholera toxin
- Diphtheria toxin
- Erythrogenic toxin of Streptococcus pyogenes