Kachur - Topic 1 - Immunity to Bacterial Pathogens

Question 1

Human microbiome

Answer 1

all the microbes that call us home

Question 2

pathogen

Answer 2

microbes that can cause disease

Question 3

infection

Answer 3

infection replicates in/on host

Question 4

disease

Answer 4

microbial infection damages host

Question 5

pathogenicity

Answer 5

• ability of an organism to cause disease
• either a yes or no

Question 6

Virulence

Answer 6

extent to which a microbe can cause disease
- how bad something effects

Question 7

Virulence factors

Answer 7

adaptations and traits that promote virulence in a pathogen

Question 8

What are the two types of pathogens

Answer 8

• opportunistic pathogens
• true pathogens

Question 9

What is a opportunistic pathogen

Answer 9

• result from opportunistic conditions:
• compromised immune system (immunodeficiency)
• disruption in the balance of normal microbes

Question 10

What are the two types of true pathogens

Answer 10

obligate and facultative pathogens

Question 11

What are obligate pathogens

Answer 11

pathogen must cause disease to be transmitted

Question 12

What is a facultative pathogen

Answer 12

can cause disease but doesn’t require host to complete life cycle

Question 13

How does the establishment of infection work

Answer 13

• presence of microorganism on host doesn’t lead to disease
• interactions between host + microbe contribute to final outcome

Question 14

What is the establishment of infection influenced by?

Answer 14

• virulence of the microbe
• defense mechanism of host (innate vs adaptive)

Question 15

What are the steps to establishment of infection

Answer 15

1. pathogen encounter/exposure
2. host entry
3. adhesion + invasion
4. immune system evasion
5. host damage
   - each step requires unique evasion strategies

Question 16

What is staphylococcus epidermis

Answer 16

• an opportunistic pathogen
• normal component of the skin + important in protecting skin from unwanted pathogens

Question 17

How do we encounter S. epidermis

Answer 17

• its very hardy and a ubiquitous component of human skin

Question 18

How does S. epidermis enter the host

Answer 18

• nosocomial (hospital-borne)
• spread through catheters, pacemakers, + plastic implants

Question 19

How does S. epidermis adhere to the host

Answer 19

• can tolerate changing osmolarity
• attaches via hydrophobic interactions
• teichoic acid associates with plastic
• bacterial components bind ECM components of host

Question 20

How does S. epidermis evade the immune system

Answer 20

• biofilms provide resistance to antibiotics + protection from AMPs
• AMP resistance through efflux pumps (extensive antibiotic resistance genes)
• PGA-poly-gamma-glutamic acid production in capsule-like exopolymer (protects against phagocytosis + AMPs)

Question 21

How does S. epidermis damage the host

Answer 21

• PSMs (phenol-soluble modulins)
• allows access to host cell resources

Question 22

What is Yersinia pestis

Answer 22

• gram negative bacilli
• discovered by Alexandre Yersin in 1894
• causative agent of bubonic plague

Question 23

How does yersinia pestis cause bubonic plague

Answer 23

• route of infection: flea bite
• replicate in macrophages
• macrophages migrate to lymph nodes -> buboes form

Question 24

Who was Roberta Koch

Answer 24

• studied the theory that microorganism cause human disease (showed cause and effect relationship between pathogen + disease)
• developed Koch’s postulates

Question 25

What are the 4 Koch’s postulates

Answer 25

• pathogen must be present in all cases of disease + absent from health animals
• pathogen must be grown in pure culture
• cause disease from culture
• be reisolated + shown to be same as original