2 DD Host-Microbe Interactions

Question 1

Definition: Infection

Answer 1

Process of establishing a relationship between microbe and host

• may/may not cause disease

Question 2

Definition: Infectious disease

types?

Answer 2

Disease caused by an infection with a microbe

Communicable - transmitted patient to patient
Non-communicable - not transmitted

Question 3

Definition: Pathogenicity

Frank vs opportunistic

Answer 3

Capacity to cause disease

Frank: microbes cause disease with normal hosts
Opportunistic: can’t usually do in healthy people, need immunocompromised

Question 4

Definition:Virulence

low vs high

Answer 4

Relative capacity to damage a host; measure of pathogenicity (ability to cause disease)

Few microbes needed for disease = high virulence
Many microbes needed for disease = low virulence

Question 5

Koch’s Postulates

Answer 5

1. Specific microbes are present regularly in characteristic lesions of the disease
2. The specific microbes can be isolated and grown in vitro.
3. Injection of the cultured microbes into animals reproduces the disease that you see in humans
4. The specific microbes can be re-isolated from lesions of the disease in animals.

• this shows that a microbe can be the cause of a specific disease

Question 6

Stages of pathogenesis of ID

Answer 6

1. Encounter
2. Entry
3. Spread
4. Multiplication
5. Damage
6. Outcome

Question 7

Typical stage in pathogenesis:

Encounter

Answer 7

1st stage

How the agent meets the host.

Question 8

Give an example of microbial ‘spreading factors’ through tissues

Answer 8

during 3rd stage

Hyaluronidase, elastase, collagenase

Question 9

how can coagulase inhibit spread of microbes.

Answer 9

coagulase: inhibits spread of microbes because it lays down fibrin to “wall off” and localize infection

Question 10

Typical stage in pathogenesis:

damage

Answer 10

5th stage

how tissue damage is cause by the agent and/or the host response

are virulence factors present?

Question 11

Typical stage in pathogenesis:

outcome

Answer 11

6th stage

does the microbial agent or the host win the battle, or do they learn to coexist?

Question 12

Innate vs. Adaptive defense against infections

Answer 12

Innate: Immediate response
Adaptive: Defends against future recurrences

Question 13

Things that affect composition of microbiome

Answer 13

1. Diet
2. Antibiotics
3. Anatomy
4. Genetics

Question 14

Importance of microbiome

Answer 14

1. Effects on tissue/organ differentiation
2. Production of vitamins by flora
3. Biochemical conversions
4. Competition with pathogens for colonization of surfaces

Question 15

If growth rate in vivo is slower than in vitro, what does that mean?

Answer 15

host defense is aiding to prevent infection

Question 16

Skin normal flora

Answer 16

Staphylococci
Enteric bacilli
Corynebacteria
Propionobacterium acnes

Question 17

Large intestine normal flora

Answer 17

Micrococcus streptococci (enterococcus)
Lactobacilli
Enteric bacilli
Clostridia
Pseudomonas

Question 18

Vaginal normal flora

Answer 18

Streptococci
Lactobacilli
Bacteroides
Mycoplasma

Question 19

What does the disease paradigm of pathogenesis mean?

Answer 19

Certain types of bacteria will result in very specific diseases

Question 20

Using disease paradigm of pathogenesis, what causes Cholera?

Answer 20

A toxin-mediated disease

Question 21

Using disease paradigm of pathogenesis, what causes Pneumococcal pneumonia

Answer 21

acute inflammation caused by invasive, extracellular bacteria

Question 22

Using disease paradigm of pathogenesis, what causes Tuberculosis

Answer 22

infection by a facultative intracellular bacterium

Question 23

What causes Rheumatic fever

Answer 23

pathology mediated by an immune response