Test 122  (Ocular microbiology)

1. Bacteria that can invade intact corneal epithelium include: 

a. Pseudomonas aeurginosa

b. Neisseria gonorrhoea

c. Haemophilus influenzae

d. Staphylococcus aureus

e. Listeria species

Answera.F  b.T  c.T  d.F  e.T
Most bacteria require a breach in the epithelium to establish corneal infection. Exceptions are Neisseria species, Haemophilus influenzae, Listeria species and corynebacterium species.
 

2. Chocolate agar contains:

a. bovine haemoglobin

b. NAD (nicotinamide adenine dinucleotide)

c. vancomycin

d. colistin

e. nystatin

Answera.T   b.T  c.F  d.F  e.F
Vancomycin, colistin and nystatin are found in Thayer-Martin medium.

 
3. Moraxella lacunata:

a. is a Gram positive bacillus

b. causes angular blepharitis

c. grows on MacConkey agar

d. causes corneal ulcer in debilitated patients

e. is sensitive to chloramphenicol

Answera.F   b.T  c.T  d.T  e.T
Moraxella lacunata is a Gram negative bacillus. It grows on MacConkey agar and does not ferment carbohydrate.
.

4. Adenovirus:

a. is a double stranded DNA virus

b. can be cultured on HeLa cell lines

c. causes conjunctivitis which responds well to 
    oral acyclovir 

d. causes pharyngoconjunctival fever

e. is implicated in acute retinal necrosis

Answera.T  b.T  c.F  d.T  e.F
Adenoviral conjunctivitis does not respond to acyclovir. Acute retinal necrosis is caused by herpes virus especially herpes-zoster or herpes simplex.

5. With regard to chlamydia trachomatis:

a. it contains both DNA and RNA

b. it can be grown on McCoy cell culture

c. trachoma is caused by subtypes D to K

d. subtypes A to C are usually sexually transmitted

e. it is sensitive to rifampicin

Answera.T   b.T  c.F  d.F  e.T
Chlamydia is an obligatory intracellular organism. 
Trachoma is caused by subtype A to C.
Subtypes D to K causes inclusion conjunctivitis which is sexually transmitted.

 
 

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