Microbial Mechanism of Pathogenicity

Question 1

LD50?

Answer 1

LD stands for lethal dose which is the dose of pathogen that will kill half of the test animals. This is a way to measure virulence [The fewer microorganisms required, the higher the virulence].

Question 2

If the pathogen causes only a nonfatal disease, the equivalent to the LD50 test is referred to as (infectious dose)?

Answer 2

ID50 (infectious dose)

Question 3

3 portals of entry?

Answer 3

1. Mucous membrane (respiratory tract, gastrointestinal tract, genitourinary tract, conjunctiva - lining of eye)
2. Skin
3. Parenteral route (the route in which the skin and mucous membranes are punctured or injured/traumatized and microorganisms can gain access to body tissues).

Question 4

3 ways of penetration or evasion of host defenses?

Answer 4

1. Capsules
2. Cell wall components
3. Enzymes

Question 5

3 ways to damage to host cells / cytopathic effects?

Answer 5

1. Direct damage
2. Toxins (Exotoxins, Endotoxins)
3. Hypersensitivity