Chapter 2: Bacterial virulence factors and toxins

Question 0

How many pigment producing bacteria are there?

Answer 0

4

1) Actinomyces israelii
2) S. aureus
3) Pseudomonas aeruginosa
4) Serratia marcescens

Question 1

Urease-positive bugs

Answer 1

“PUNCH KSS” (or CHuck Norris hates PUNKSS)

1) Proteus
2) Ureaplasma
3) Nocardia
4) Cryptococcus
5) H. pylori
6) Klebsiella
7) S. epidermidis
8) S. saprophyticus

Question 2

What pigment does Actinomyces israelii produce?

Answer 2

“Israel has yellow sand”

Actinomyces israelii appear as yellow “sulfur” granules, which are composed of filaments of bacteria

Question 3

Which microbe appears as yellow “sulfur” granules, composed of filaments of bacteria?

Answer 3

Actinomyces israelii

“Israel has yellow sand”

Question 4

What pigment does S. aureus produce?

Answer 4

yellow

aereus means gold in Latin

Question 5

Which microbe produces a yellow pigment?

Answer 5

Staph. auerus

aureus means gold in Latin

Question 6

Pseudomonas aeruginosa produces what pigment?

Answer 6

blue-green pigment

AERUGala is green

Question 7

What microbe produces a blue-green pigment?

Answer 7

Pseudomonas aeruginosa
(AERUGala is green)

Question 8

Serratia marcescens produces what color pigment?

Answer 8

red pigment

think red maraschino cherries for marcescens

Question 9

What microbe produces a red pigment?

Answer 9

Serratia marcescens

think red maraschino cherries for marcescens

Question 10

What is the function of the virulence factor, Protein A?

Answer 10

Protein A binds the Fc region of IgG and prevents opsonization and phagocytosis.

Question 11

What virulence factor binds the Fc portion of IgG to prevent opsonization and phagocytosis?

Answer 11

Protein A

Question 12

What microbe expresses IgA?

Answer 12

S. auerus

Question 13

What is the function of the virulence factor IgA protease?

Answer 13

IgA protease cleaves IgA to allow certain bacteria to colonize respiratory mucosa (recall IgA antibody plays a critical role in mucosal immunity)

Question 14

What virulence factor allows bacteria to evade mucosal immunity and colonize respiratory mucosa?

Answer 14

IgA protease

Question 15

IgA protease is expressed by which bacteria? (3)

Answer 15

“SHiN”

1) S. pneumoniae
2) H. influenzae type B
3) Neisseria

Question 16

What is the function of M protein?

Answer 16

M protein inhibits the action of complement to prevent phagocytosis

Question 17

What virulence factor inhibits complement to prevent phagocytosis?

Answer 17

M protein

Question 18

What microbe expresses M protein?

Answer 18

Group A streptococci (Strep. pyogenes)

Question 19

Exotoxins are produced by what type of bacteria?

Answer 19

Exotoxins are released by most of the major gram-positives, and some species of gram-negative bacteria

Question 20

Endotoxins are produced by which type of bacteria?

Answer 20

Most gram-negative bacteria (recall endotoxin, or Lipid A, is a component of LPS which is located on the outer cell membrane)

Question 21

Are exotoxins or endotoxins secreted from the cell?

Answer 21

Exotoxins are secreted

Endotoxins are released upon lysis of gram-negative bacteria

Question 22

What is the chemical composition of exotoxins versus endotoxins?

Answer 22

Exotoxins are composed of polypeptide.

Endotoxins are composed of lypopolysaccharide LPS

Question 23

Are exotoxins or endotoxins composed of polypeptide?

Answer 23

Exotoxins are composed of polypeptide

Question 24

Are exotoxins or endotoxins composed of lipopolysaccharide??

Answer 24

Endotoxins are composed of LPS

Question 25

What is the difference in location of genes of exotoxins versus endotoxins?

Answer 25

Exotoxin genes are located in plasmids or bacteriophages. | Endotoxin genes are located on the bacterial chromosome.

Question 26

Where are exotoxin genes located?

Answer 26

On plasmid or bacteriophage DNA

Question 27

Where are endotoxin genes located?

Answer 27

On bacterial chromosome

Question 28

Genes encoding which (exotoxin or endotoxin) are located on plasmids or bacteriophage DNA?

Answer 28

Exotoxin

Question 29

Genes encoding which (exotoxin or endotoxin) are located on bacterial chromosomes?

Answer 29

endotoxin

Question 30

What is the difference in toxicity of exotoxins versus endotoxins?

Answer 30

Exotoxins have high toxicity (fatal dose on the order of 1 ug). Endotoxins have low toxicity (fatal dose on the order of hundreds of micrograms).

Question 31

What is the difference in antigenicity of exotoxins versus endotoxins?

Answer 31

Exotoxins induce high-titer antibodies called antitoxins. | Endotoxins are poorly antigenic.

Question 32

Are vaccines available or exotoxins or endotoxins?

Answer 32

Toxoids (endotoxins) used as vaccines. | No toxoids are formed for endotoxins, so no vaccine is available.

Question 33

What is the difference in heat stability of exotoxins versus endotoxins?

Answer 33

Exotoxins are destroyed rapidly at 60C (except for staphylococcal enterotoxin). Endotoxins are stable at 100C for 1 hr.

Question 34

Which (exotoxins or endotoxins) are destroyed rapidly at 60C?

Answer 34

Exotoxins (except staphylococcal enterotoxins)

Question 35

Which (exotoxins or endotoxins) are stable at 100C for 1hr?

Answer 35

Endotoxins

Question 36

What are typical diseases associated with exotoxin? (3)

Answer 36

1) Tetanus 2) Botulism 3) Diphtheria

Question 37

Tetanus, botulism, and diphtheria are associated with (exotoxin or endotoxin)?

Answer 37

Exotoxin

Question 38

What diseases are typically caused by endotoxins? (2)

Answer 38

1) Meningococcemia | 2) Sepsis by gram-negative rods

Question 39

Meningococcemia and sepsis are typical diseases caused by (exotoxin or endotoxin)?

Answer 39

Endotoxin

Question 40

Bacteremia - defn

Answer 40

bacteria in the bloodstream

Question 41

Sepsis - defn

Answer 41

Bacteremia that causes a systemic immune response to the infection: - high or low temperature - elevation of WBC - fast heart rate - fast breathing rate

Question 42

Septic shock - defn

Answer 42

Sepsis that results in dangerous drops in blood pressure (hypotension) and organ dysfunction (severe sepsis).

Question 43

mnemonic for characteristics of endotoxin?

Answer 43

ENDOTOXIN 1) Edema 2) Nitric oxide 3) DIC 4) Outer membrane 5) TNF-a 6) O-antigen 7) eXtremely heat stable 8) IL-1 9) Neutrophil chemotaxis

Question 44

Endotoxin (Lipid A) activates which 3 pathways?

Answer 44

1) macrophages 2) complement 3) tissue factor

Question 45

Endotoxin activates macrophages to release what 3 endogenous mediators of sepsis? What are the associated clinical signs?

Answer 45

1) TNF-a - fever and hypotension 2) IL-1 - fever 3) Nitric oxide - hypotension

Question 46

Endotoxin activates complement (which 2 components) which leads to what clinical signs? (2)

Answer 46

1) C3a - edema, hypotension | 2) C5a - neutrophil chemotaxis

Question 47

Endotoxin activates the C3a component of complement which leads to what clinical signs?

Answer 47

Edema and hypotension

Question 48

Endotoxin activates the C5a component of complement which leads to what clinical sign?

Answer 48

Neutrophil chemotaxis

Question 51

Endotoxin activates tissue factor which can lead to what clinical sign?

Answer 51

coagulation cascade -> DIC

Question 52

What vital interventions should be performed immediately (<1 hr) of a diagnosis of sepsis?

Answer 52

The septic six: BUFALO 1) blood - draw blood cultures them prior to antibiotic administration 2) urine - insert urinary catheter and monitor hourly urine output 3) fluid - treat hypotension with IV fluids and drugs (dopamine and norepinephrine) 4) antibiotics - administer empiric broad spectrum antibiotics stat 5) lactate (and hemoglobin) - measure serum lactate and hemoglobin levels, associated with mortality 6) oxygen - maintain oxygenation, often with high flow O2 with intubation and mechanical ventilation