Test 35
(Matching Paper: Microbiology)

In response to considerable discussion the Examinations Committee of the College has decided to update the format of the Part 3 MRCOphth Examination from April, 2003.

An extended matching paper will replace the existing MCQs and they will be no negative marking. The test will probably be easier than the previous format. To familiarize the candidates with the new formats, test 34 and onward will follow the new style as described below by the College.
 

40 questions over a 3-hour period. The questions will be divided as follows. 5 pathology questions 5 microbiology questions 15 general ophthalmology questions 15 Medicine and Neurology in relation to ophthalmology Extended matching questions are multiple choice items organized into sets that use one list of items in the set. The extended matching set includes four components  1.A theme  2.an option list  3.a lead in statement  4.at least four item stems, as illustrated below  This will involve 40 questions (probably 200 stems) over a period of 3 hours.

1. Match the stem questions (a-d) with the options (A-L) listed below:
 

A. Gram positive coccus B. Gram negative coccus C. Gram positive bacillus D. Gram negative bacillus E. Acid fast bacilli  F. Cytoplasmic inclusion bodies     on Giemsa staining

G. Multi-nucleated cells and inclusion bodies       on Tzanck test H. Grow on agar plate overlaid with E.coli I.   Stained with Gomori methenamine silver J.   Stained with Congo red K.  Stained with Sudan black L.   Stained with Ziehl-Neelsen stain

 

a.	A 25 year old woman presented with a painful right corneal ulcer with thick mucous adherent to the defect. 24 hours earlier, she scratched her right cornea while removing a soft contact lens.  Answer D. The rapid onset and thick mucous at the site of the ulcer in a contact  lens user is suggestive of Pseudomonas aeruginosa, a Gram negative bacillus.
b.	A 25 year old man has a right follicular conjunctivitis that recurs when  topical steroid is stopped. He is also under the genitourinary clinic for  non-specific urethritis. Answer F. Recurrent follicular conjunctivitis in a patient with non-specific urethritis suggests chlamydial conjunctivitis. Giemsa staining of the conjunctival scrap will show cytoplasmic inclusion bodies.
c.	A 70 year old man develops vesicles in his right forehead which are painful. The right eye is red and has mucous discharge. Answer G. The clinical features are that of ophthalmic shingle. Tzanck smear of the fluid taken from the vesicles typically show multinucleated cells  and inclusion bodies. These features are also seen in herpes simplex.
d.	A 25 year old male intravenous drug user presents with blurring of the  right eye. Examination reveals the presence of vitritis and multiple fluffy white lesions. Answer I. The history is suggestive of endophthalmitis caused by candidiasis.  The pathogen takes up Gomori methenamine silver stain readily.

2. Match the stem questions (a-d) with the options (A-L) listed below:
 

A. Gram positive coagulase positive coccus B. Gram positive coagulase negative coccus C. Gram positive aerobic bacillus D. Gram negative catalase positive coccus E. Gram negative catalase negative coccus F. Gram negative bacillus

G.  double-stranded DNA virus H.  single-stranded DNA virus I.   double-stranded RNA virus J.   single-stranded RNA virus K.  acid-fast bacilli L.  acid-fast coccus

 

a.	A new born child has bilateral cataracts and neurosensory deafness. Fundoscopy reveals pigmentary changes of the retina. Answer J. Congenital rubella is the most likely diagnosis. Rubella is a single-stranded RNA virus belonging to the togavirus family.
b.	A 70 year old develops recurrent iritis four months after an uneventful cataract  surgery. The iritis recurs when topical steroid is discontinued. Slit-lamp  examination reveals a plaque in the posterior capsule. Answer B. The history and clinical sign are suggestive of low-grade bacterial  endophthalmitis. Two bacteria are commonly implicated: Staphylococcus epidermidis and Propionibacterium acne. Staphylococcus epidermis is  a Gram positive coagulase negative coccus whereas Propionibacterium  acne is a Gram positive anaerobic bacillus.
c.	A 35 year old man who is HIV positive develops a white lesion in the peripheral retina with mild vitritis. The lesion enlarges over the next two weeks with dot haemorrhages. Answer G. The most likely diagnosis is cytomegalovirus retinitis. CMV virus belongs to the family of herpes virus and contains double-stranded DNA.
d.	A 2 day old baby has bilateral purulent ocular discharge. The mother has a history of vaginal discharge but receives no treatment. Answer D. The history and signs are suggestive of neonatal ophthalmia caused by Neisseria gonococcus which is a Gram negative catalase negative bacteria.

 

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