DMF Week 9 SAQ

1

Which one or more of the techniques listed below would be useful in the diagnosis of the cause of gastroenteritis in several members of a family?

A - Culture of faeces on a range of microbiological media

B - Culture of faeces in cell cultures for the detection of viruses

C - Microscopic examination of a wet preparation of faeces

D - Gram stain of faeces


2

Which one or more of the following statements describe the mechanisms by which pathogenic E. coli cause diarrhoea?

A - The release of heat-stable enterotoxin

B - The invasion of colonic epithelium

C - The production of attachment-effacement lesions

D - The production and release of cytotonic toxins


3

Which one or more of the following statements about parasite lifecycles is/are correct?

A - Parasites always reach sexual maturity in the reservoir host.

B - Definitive hosts of parasites differ from intermediate hosts because, although development occurs in both, sexual maturity only occurs in the definitive host.

C - Parasites only replicate in the reservoir host.

D - In paratenic hosts, parasites remain infective but do not undergo development.


4

Which one of the following statements about malaria caused by Plasmodium falciparum is correct?


5

A 45 yr old non-Caucasian male was referred to the emergency department of the local hospital with malaise, headache and myalgia for the past week. He had no relevant medical history, and was not taking any medications. On examination, he had a temperature of 38oC. Physical examination was normal, however his pulse rate was slow. He had visited his brother in India, and had returned one week ago. He took prophylaxis for malaria, and had been vaccinated against hepatitis A and B, cholera, Japanese encephalitis and polio.

Which one or more of the specimens below is appropriate for the diagnosis of his condition?

A - Three sets of blood cultures

B - Blood for serology

C - Thick and thin blood films

D - A faeces sample


6

No parasitic forms were seen in any of the specimens collected from the patient above. A bacterium considered to be the cause of his infection was grown from appropriate specimens. The organism was a Gram negative bacillus, which grew on HBA (horse blood agar) in aerobic and anaerobic conditions. The organism produced a colony of 2 mm diameter on MacConkey agar, and was a lactose non-fermenter.

Which one of the organisms listed below is the most likely cause of the patient’s condition?


7

Which one of the antimicrobial agents listed below would be most appropriate for this patient?