Mechanisms of Bacterial Pathogenesis

Question 1

List 3 terms to describe an infection where the host defenses clear the pathogen before any disease symptoms are noted.

Answer 1

Asymptomatic, subclinical, or inapparent

Question 2

What term describes an infection that can be passed from host to host?

Answer 2

Communicable

Question 3

What term describes a highly communicable infection?

Answer 3

Contagious

Question 4

What term describes an infection that comes from the environment, not from a previous host?

Answer 4

Noncommunicable

Question 5

Are Botulism and Legionnaires disease examples of communicable, contagious, or noncommunicable infections?

Answer 5

Noncommunicable

Question 6

What term describes a host that survives an infection but continues to shed the pathogen?

Answer 6

Chronic carrier

Question 7

What term describes an infection where the disease symptoms subside, but the microbe remains in the body and can later reactive?

Answer 7

Latent infection

Question 8

What term describes microbes (like viruses) that require host cells to reproduce?

Answer 8

Obligate intracellular parasites

Question 9

What term describes microbes that can reproduce either inside or outside of host cells?

Answer 9

Facultative intracellular parasites

Question 10

What is the difference between an ID50 and LD50?

Answer 10

Infectious dose is the dose at which 50% of people will become sick; Lethal dose is the dose at which 50% of people will die.

Question 11

Which has higher virulence: an ID50 of 30 or an ID50 of 300?

Answer 11

30

Question 12

Which has higher virulence: an LD50 of 10 or an LD50 of 100?

Answer 12

10

Question 13

A Bacterium that has Mid-Low Pathogenicity and a Low Infectious Dose is most likely what?

Answer 13

An opportunistic pathogen

Question 14

Is pH tolerance a virulence factor that helps bacteria: survival in extreme environments, adherence to host surfaces, immune evasion, intracellular survival, or poison the host?

Answer 14

Survival in extreme environments

Question 15

What is the term for a bacteria that can steal iron from the hemoglobin of RBCs?

Answer 15

Siderophore

Question 16

Are curli a virulence factor that helps bacteria: survival in extreme environments, adherence to host surfaces, immune evasion, intracellular survival, or poison the host?

Answer 16

Adherence to host surfaces

Question 17

Is IgA protease a virulence factor that helps bacteria: survival in extreme environments, adherence to host surfaces, immune evasion, intracellular survival, or poison the host?

Answer 17

Adherence to host surfaces and immune evasion

Question 18

What does serum resistance allow bacteria to do?

Answer 18

Disrupt the complement cascade, evade the immune system

Question 19

Is antigenic variation a virulence factor that helps bacteria: survival in extreme environments, adherence to host surfaces, immune evasion, intracellular survival, or poison the host?

Answer 19

Immune evasion

Question 20

Are capsules and M proteins virulence factors that help bacteria: survival in extreme environments, adherence to host surfaces, immune evasion, intracellular survival, or poison the host?

Answer 20

Immune evasion

Question 21

LPS, LOS, and teichoic acids are all examples of what?

Answer 21

Endotoxins

Question 22

Which bacteria is best known for its actin polymerization “rockets”?

Answer 22

Listeria monocytogenes

Question 23

What term describes an inanimate object or substance capable of transferring infectious organisms between hosts?

Answer 23

A fomite

Question 24

Are endosome escape pathways virulence factors that help bacteria: survival in extreme environments, adherence to host surfaces, immune evasion, intracellular survival, or poison the host?

Answer 24

Intracellular survival

Question 25

Are type 3&4 secretion systems virulence factors that help bacteria: survival in extreme environments, adherence to host surfaces, immune evasion, intracellular survival, or poison the host?

Answer 25

Poison the host/host cell takeover - T3SS and T4SS can inject genes and exotoxins into a host cell.

Question 26

How does Legionella survive after it is taken up by phagocytosis?

Answer 26

It prevents the phagosome from fusing with a lysosome, or else inhibits the phagosome from acidifying

Question 27

Coagulase is a Staph. aureus virulence factor that does what?

Answer 27

Break down fibrinogen to form a fibrin clot around S. aureus

Question 28

Superantigens belong to what class of bacterial molecules that can also interfere with signal transduction and depolymerize actin?

Answer 28

Exotoxins

Question 29

Endotoxins cause an inflammatory immune response that is dominated by what 2 cytokines?

Answer 29

TNF and IL-1

Question 30

Are vaccines more useful against endotoxins or exotoxins?

Answer 30

Exotoxins - vaccines cannot help against endotoxins

Question 31

In a typical infectious disease timeline, what is the name for the stage dominated by nonspecific immunogenic symptoms like fever and fatigue?

Answer 31

Prodrome period

Question 32

In a typical infectious disease timeline, what is the name for the stage where pathogen-mediated symptoms emerge most strongly?

Answer 32

Specific-illness period

Question 33

Name the 4 steps of a typical infectious disease timeline.

Answer 33

Incubation - Prodrome - Specific-illness - Convalescence/recovery