Staphylococcus Aureus Gram positive

Question 1

Classification of Staph Aureus

Answer 1

Shape: Cocci
Catalse: Negative
Coagulase: positive

Question 2

name an important toxin produced by staph aureus that causes shock, fever, rash or scaled skin sydrome ?

Answer 2

TSST-1

Toxic Shock Syndrome Toxin

Question 3

what is the mechanism of the TSST-1 toxin in staph aureus?

Answer 3

Cross links B-region of the TCR to MHC class II on APC:

Severly overwhelms immune response:
IL-1
IL-2
IFN- y
TNF alpha

key: overwhelms the release of interleukins

Question 4

Describe the virulence factor Protein A

Answer 4

Protein A is one of the virulence factor of staph aureus: It binds to Fc-IgG to stop phagocytosis

Question 5

common sites of staph Aureus

Answer 5

Nares
ears
axilla
groin

Question 6

describe MRSA

Answer 6

Important cause of serious nosocomial and community accuired infections

Key: Reistant strain due to Pencillin-Binding proteins

Question 7

A super antigen that binds to MHC class II and T-cell receotor resulting in T-cell activation (agitation) and CYTOKINE craze (release)

Answer 7

TSST-1

Question 8

Common source of Toxic Shock staph infection

Answer 8

nasal packing
Tampons

Question 9

What does coagulase positive mean in Staph Aureus ?

Answer 9

Coagulase means “CLOT”
so staph aureus forms fibrin and clots around itself