Test 137  (Microbiology)

1. The following are live vaccines

a. tetanus

b. hepatitis B

c.  measles

d.  mumps

e.  rubella
 

Answer
a.F   b.F   c.T   d.T   e.T
Live vaccines include:
Measles
Mumps
Rubella
Oral polio vaccine (OPV)
.

2. The following are recognized features of onchocerciasis:

a. keratitis

b. chorioretinal atrophy

c  "hanging groin"

d.  pruritis

e.  depigmentation

Answer
a.T   b.T   c.T   d.T  e.T
Causative organism: Onchocerca volvulus 
Vector: Simulium fly
Distribution: Equatorial Africa, Yemen, S.America
Other hosts: Adult worms are only found  in humans.
Life cycles: Adult worms live in subcutaneous tissue. 
They may also be found in fibrotic nodules. Female 
worms produce many microfilariae which may be taken 
up by Simulium when it bites. After several weeks in 
the fly the microfilariae develop into infective larvae.
Clinical features: pruritus, depigmentation , "hanging groin", keratitis, retinal changes.
Treatment: Ivermectin

3. Loa loa:

a. is confined to Central and West Africa

b. is spread by mosquito

c. may cause a high eosinophilia 

d. is diagnosed by histological examination of skin snips

e. is treated with diethylcabamazine citrate

Answera.T  b.F  c.T  d.F  e.T
High eosinophilia is particularly suggestive of infection 
with filarial worms or strongyloidiasis.
The vector is a fly of the genus Chrysops.
The diagnosis is usually made by finding microfilariae 
in the blood. Adult worms are sometimes (dramatically)
seen crossing the eye subconjunctivally. Adult worms are 
also located in the pathognomonic Calabar swellings.
.

4. Staphylococcus epidermidis:

a. is coagulase positive

b. on microscopy are Gram positive cocci in chains

c. are usually sensitive to penicillin

d. grown in blood cultures are due to contamination and 
    should be ignored

e. are destroyed by povodine iodine

Answer
a.F   b.F  c.F  d.F   e.T
Staph. epidermidis is part of the normal skin flora.
As for Staph. aureus, Gram positive cocci in bunches 
are seen on microscopy.
It is usually insensitive to penicillin.
Although it is often a contaminant in blood cultures,
it is associated with line infections. Central venous catheters are an especially likely site of infection 
even in the absence of overt exit site sepsis. They 
should not be ignored but interpreted in the clinical 
context, and usually the blood cultures should be repeated.
In patients with central lines, blood cultures should be taken both peripherally and from the central line as semi-quantitative microbiological techniques are available that may point to the central line as the principle site of infection.

5. HIV-associated Kaposi's sarcoma is 

a. radiosensitive

b. chemosensitive

c. may be mistaken for subconjunctival haemorrhage

d. more common in intravenous drug abusers than 
    homosexuals

e. associated with infection by HHV-8 (Herpes hominis 
    virus type 8)

 
Answer
a.T   b.T  c.T  d.F   e.T
The skin and palate are particularly common sites for Kaposi sarcoma (KS). Cutaneous and lymph node KS responds to radiotherapy. Systemic KS (i.e. bowel, pulmonary) responds to chemotherapy: vincristine, bleomycin, etoposide.
Involvement of the conjunctiva may give the eye a red 
appearance which may be mistaken for subconjunctival haemorrhage.
Human Herpes virus type 8 DNA sequences have been found in KS, both HIV-related and HIV-unrelated. KS is more common in sexually acquired HIV 
suggesting that there may be sexually acquired co-factor for the development of KS. Human Herpes virus type 8 DNA has also been isolated from AIDS-related body cavity lymphoma.
.

 

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