Microbiology Shohaib

Question 1

name the three mechanisms that can cause diarrhea

Answer 1

1. Secretory-> No fever, water is stool (v.cholea, EHEC, e.coli)
2. Inflam-> fever, WCC in stools [neuts] (campylobacter, shigella)
3. Enteric-> Fever, WCC [mono] (typhoid)

Question 2

Give microbiology features of Staph A.

Answer 2

gram positive cocci (round)
catalase and coat +ve
tetrad clusters on gram stain
(skin lesions of food handlers)

Question 3

How does secretory diarrhoea happen?

Answer 3

Toxin production (super antigen)-> bind to t cell-> cytokine release

Question 4

how does staph A cause diarrhea

Answer 4

superantigen in GI tract-> IL1 and IL2 release-> watery diahreea, no blood, vomiting

SELF LIMITING

Question 5

Micro of Bacillus cereus

Answer 5

gram positive rod-spores
heat stable enteric toxin (reheating rice)
heat labile diarrhoea toxin

Question 6

how does B.Cereus cause diarrhoea

Answer 6

1. heat stable enteric toxin (not destroyed by rehearing)
2. heat labile diarrhoea toxin (not cooked enough)

watery non bloody-> Self limiting

can cause bacteria and cerebral accesses