Mechanisms of bacterial virulence

Question 1

What is the difference between bacteriostatic and bactericidal?

Answer 1

Bacteriostatic - stops proliferation

Bactericidal - kills bacteria

Question 2

What is the difference between LPS/LOS and lipoteichoic acid?

Answer 2

Gram-negative bacteria have LPS/LOS, and gram-positive bacteria have lipoteichoic acid.

Question 3

Virulence factors: what is LPS?

Answer 3

• Impedes destruction of bacteria

- May be involved in adherence, or antigenic shifts that determine the course of infection.

Question 4

Virulence factors: what is a capsule?

Answer 4

A capsule protects against complement-mediated killing.

Question 5

Virulence factors: what do enterotoxins do? Example of one?

Answer 5

They affect the permeability of the small intestine. Ex) shiga toxin.

Question 6

What kind of toxin is LPS? What is it made out of?

Answer 6

An endotoxin. Carbohydrate (variable between species) and lipid A (constant between species).

Question 7

What are some surface-localized virulence factors?

Answer 7

Flagella, fibrin, pili.

Question 8

Monotrichous

Answer 8

One flagellum on one pole (of bacteria)

Question 9

Lophotrichous

Answer 9

Multiple flagella on each pole

Question 10

Amphitrichous

Answer 10

One flagellum on each pole

Question 11

Peritrichous

Answer 11

Many flagella all over

Question 12

T1SS

Answer 12

Very simple, three component, sec-independent pathway

Question 13

T2SS

Answer 13

Sec-dependent, much more complicated than T1SS. 12-16 components that polymerize and “push” toxin such as cholera toxin through the pore.

Question 14

T3SS

Answer 14

Single step injectasome secretion. Related to bacterial flagella. Sec-independent.

Question 15

T4SS

Answer 15

Sec-independent. Versatile, found in gram -/+ and secrete wide range of substances, including DNA.

Question 16

T5SS

Answer 16

Sec-dependent. Have auto-transporters and two-partner secretion systems.

Question 17

What interacts with toll-like receptors on immune cells?

Answer 17

LPS, peptidoglycan, lipoteichoic acid, flagellin, and unmethylated CpG sequences on the bacterial cell walls.

Question 18

Flagella:
Fimbriae:
Pili:
Adhesion:
Afimbrial adhesins:

Answer 18

Flagella: Long things that help bacteria move. Can be located all over, on one pole, or both poles of bacteria.
Fimbriae: Long structures that mediate attachment.
Pili: Can be extended or retracted to facilitate movement. Also aides in conjugation.
Adhesion: A ligand that assists in attachment and colonization to a host cell.
Afribrial adhesins: surface proteins not related to fimriae, and not organized like pili. Wide variation.