Staphylococci

Question 1

Describe the appearance of staphylococci under a microscope

Answer 1

Gram positive - purple

Grape like clusters

Question 2

What can staphylococcus infection cause?

Answer 2

Pneumonia 
Endocarditis 
Septicaemia
Toxic shock
UTI
Gastroenteritis 
Cellulitis

Question 3

Describe the features of toxic shock

Answer 3

Fever
Hypotension
Erythematous rash (desquamation)
GI/Renal/Hepatic damage

Question 4

How does staphylococcus aureus cause toxic shock?

Answer 4

Produces toxins that stimulate T cells to produce excess cytokines, causing widespread vasodilation

Question 5

What are the virulence factors for staphylococcus aureus?

Answer 5

Antiphagocytic effect - produces proteins that bind to IgG
Damage cell membranes - produce exotoxins
Induce toxic shock - produce toxins that stimulate T cells to excessively produce cytokines
Produce enzymes that disrupt normal cell function - coagulase, catalase, fibrinolysin

Question 6

What is staphylococcus aureus treated by?

Answer 6

Methicillin susceptible - oxacillin

Methicillin resistant - vancomycin

Question 7

Why is staphylococcus epidermis not usually a problem?

Answer 7

Low virulence factors

Part of normal skin flora

Question 8

When does staphylococcus epidermis cause infection?

Answer 8

In valve and catheter procedures

Question 9

How is staphylococcus epidermis treated?

Answer 9

Oxacillin

Vancomycin