Mechanisms of Bacterial pathogenesis

Question 1

What are commensals?

Answer 1

coexist (neutral relationship) however, the commensals are kind of beneficial when kept in check as they gobble up resources that would otherwise be used by more harmful bacteria.

Question 2

What are opportunistic pathogens?

Answer 2

pathogens that take advantage of breaks/disruption in the most defense system

Question 3

What are primary pathogens?

Answer 3

cause disease on their own (have factors that damage the host)

Question 4

What must a bacteria do to be considered a pathogen?

Answer 4

the bacteria must case damage to the host (colonizing isn’t enough to be considered a pathogen)

Question 5

What must a primary pathogen be able to do in order to cause disease?

Answer 5

1) breach cellular/anatomical barriers (innate defenses)
- gain access to unique niches where there is less competition from other micoorganisms
2) avoid host defense - circumvent, exploit, subvert, and even manipulate normal host defenses
3) transmission: long term survival is dependent on ability to replicate, survive, and be transmitted to another host

Note: if the pathogen is too deadly/kills the host they will no longer have a place to colonize

Question 6

What non-inducible innate host defense mechanisms are most important at various sites within the body?

Answer 6

• lysozyme - saliva and tears
• cilia - trachea
• acid- stomach
• mucus - intestinal tract
• sebum - intact skin
• flushing action - urinary tract

Question 7

What is meant by an invasive pathogen and what an invasion is?

Answer 7

invasive pathogen is a pathogen that invades host cells or tissues where a bacteria are not normally present. Invasive bacteria can use invasions, a protein produced by the bacteria that allows it to invade non-phagocytic host cells or host tissues.

Question 8

Mechanism used by primary pathogens to cause injury: Exotoxins

Answer 8

inhibitory, stimulatory, or fatal (usually bind to specific cell receptors) - creates pores in host cell membranes

Question 9

Mechanism used by primary pathogens to cause injury: endotoxins

Answer 9

induces fever through release of IL-1 and TNF. (lipid A portion of Lipopolysaccharide/LPS) this can lead to inflammation

Question 10

Mechanism used by primary pathogens to cause injury: Hydrolytic enzymes

Answer 10

facilities tissue invasions

Question 11

Mechanism used by primary pathogens to cause injury: super antigen

Answer 11

causes the massive release of cytokines which activate non specific T cells through binding to MHC II (toxic shock)

Question 12

Mechanism used by primary pathogens to cause injury: inflammation

Answer 12

chronic inflammation can lead to improper organ function/damage host tissue