a. is sensitive to fusidic acid

b. is resistant to phagocytosis by neutrophils

c. produces exotoxins

d. is the most common cause of carbuncle

e. phage type I and II are the commonest cause of boils

Answera.T   b.F   c.T   d.T   e.T

2. The following can be used to identify Staphylococcus aureus:

a. identification of Lancefield groups through serology

b. phosphatase positivity

c. coagulase positivity

d. fermentation of mannitol

e. golden appearance of colonies

Answera.F   b.T   c.T   d.T   e.T
Lancefield group identification is for Streptococcus.
The colonies are typically golden but may range from orange to white.

3. The effect of endotoxins include:

a. inhibition of platelet aggregation

b. inhibition of Hageman factor

c. release of interleukin 1

d. initial leucopenia

e. activation of the alternative complement pathway.

Answera. F   b.F   b.T   d.T   e.T
Endotoxins stimulate platelet aggregation.
It activates Hageman factor (also called factor XII) which in turn activate the clotting cascade, the kinin system.
The release of interleukin 1 is the cause of fever.
 

a. it is a strict anaerobe

b. it is a bacteria

c. it causes chronic canaliculitis

d. it is usually sensitive to penicillin

e. infection is associated with discharges containing yellow sulphur granules.

Answera.T   b.T  c.T   d.T   e.T
 

a. vancomycin and penicillin inhibit bacterial cell wall synthesis through 
    the same mechanisms.

b. vancomycin is poorly absorbed from the gut

c. metronidazole crosses the blood-brain barrier readily

d. sulphonamides crosses the blood-brain barrier readily

e. chloramphenicol is active against Pseudomonas bacteria

Answera.F   b.T   c.T  d.T   e.F
Vancomycin and penicillin act on the cell wall of bacteria but via different mechanisms.
Chloramphenicol is not active against Pseudomonas bacteria and should therefore not be prescribed in contact-lens associated infection (which is mainly caused by Pseudomonas).
 
 
 

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