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Part 1 Examination in Medical Microbiology and Virology
Sample MCQs and EMQs
Multiple Choice Questions
Question 1 The cell wall of gram-positive bacteria may contribute to the development of septic shock.
Identify the component which is most associated with the induction of septic shock.
A Capsular protein B Endotoxin C Peptidoglycan D Phospholipid E Teichoic acid
Question 2 Genetic variation in viruses contributes to their ability to evade the immuneresponse.
Select the principal means by which antigenic shift occurs in influenza A virus.
A Low fidelity of DNA dependent DNA polymerase B Low fidelity of RNA dependent RNA polymerase C Low fidelity of reverse transcriptase D Reassortment of fragments of the RNA genome E Recombination between RNA genomes
Question 3 A 34 year old man with diabetic ketoacidosis develops headache, nasal congestion, periorbital swelling and a bloodstained nasal discharge. Over a period of a week he become drowsy and unresponsive. ENT examination shows black, necrotic lesions on the nasal septum, which is perforated. A lumbar puncture is performed but the CSF findings are entirely normal. Culture of the nasal discharge shows a heavy growth of Streptococcus pneumoniae and Staphylococcus aureus.
Select the most likely diagnosis.
A Dental abscess B Nasal diphtheria C Orbital cellulitis D Rhinocerebral mucormycosis E Severe maxillary sinusitis
Question 4 The aminoglycosides are a very active group of antibacterial agents, particularly against Gram-negative bacilli.
Identify their mode of action from the list.
A Disruption of cytoplasmic membrane function B Inhibition of bacterial cell wall synthesis C Inhibition of bacterial DNA gyrase D Inhibition of protein synthesis E Interference with bacterial folic acid metabolism
A 22-year old female medical student recently returned from Tanzania presents with a history of haematuria. On investigation schistosomal serology is shown to be positive.
Select the treatment of choice.
A Albendazole B Ivermectin C Mebendazole D Praziquantel E Suramin
Question 6 Many antiviral drugs act by inhibition of a viral DNA polymerase enzyme.
Select the virus for which this class of drugs would be effective.
A Cytomegalovirus B Influenza C Measles D Mumps E Rabies
Question 7 You are informed of an outbreak of diarrhoea and vomiting amongst the 100 guests at a wedding reception. About two thirds of the guests became ill between 2 and 3 days after the reception. You obtain a list of guests and the menu for the buffet meal.
Select the most appropriate epidemiological investigation.
A A case-control study B A correlational study C A cross- sectional study D A randomized controlled trial E A retrospective cohort study
Question 8 A 26 year old pregnant lady (17/40 gestation) consulted her general practitioner (GP) because her 2 year old son has a vesicular rash on his hands and in his mouth. The mother is concerned about her unborn child. The GP is experienced and confident of his diagnosis of hand foot and mouth disease, but telephones you regarding further management.
Choose the most appropriate advice.
A Phone the local CCDC to find out if there is a current epidemic B Reassure the mother that there is no risk to the pregnancy C Refer the lady for fetal ultrasound scan D Send a vesicle fluid from the child for EM studies E Send blood for serological examination
Question 9 A mother takes her 6 year old son to her general practitioner (GP) extremely anxious because the child has that morning stabbed himself with a needle he found in a park frequented by drug users. Apart from a minor scratch to the right hand the child is otherwise well and has no past medical history of note.
Select the most appropriate action for the GP at this consultation.
A Issue HIV post exposure prophylaxis to the child B Reassure the mother and suggest an accelerated course of Hepatitis B vaccine C Send the needle to the lab for testing D Suggest accelerated course of Hepatitis B vaccine and Hepatitis C immunization E Test the child for Hepatitis C, HIV, Hepatitis B surface antigen
A male baby is born at 39 weeks gestation with a petechial rash, low birthweight, hepatosplenomegaly and bilateral cataracts. This is thought to be due to an infection acquired while the baby was still in utero.
Select the condition which is most likely to cause this clinical presentation.
A Cytomegalovirus B Group B streptococcus C Rubella virus D Toxoplasma gondii E Treponema pallidum
Question 15 The complement fixation test (CFT) has largely been replaced by improved assays for evidence of infection.
Select the organism for which CFT remains a useful laboratory diagnostic test of infection.
A Coxiella burnetii B Cytomegalovirus C Herpes simplex virus D Neisseria gonorrhoeae E Parainfluenza type 3
Extended Matching Questions
Question 1
Option list A Chlorhexidine B Chloroxylenol disinfectant (e.g. ‘Dettol’) C Clear soluble phenolic disinfectant (e.g. ‘Hycolin’) D Downward-displacement autoclave (e.g. 121ºC for 15 minutes) E Glutaraldehyde 2% solution F High-vacuum, high-temperature (porous load) autoclave G Hydrogen peroxide 3% H Hypochlorite solution (125 parts-per-million available chlorine) I Isopropanol 70% J Sodium dichloroisocyanurate granules or tablets (e.g. ‘Presept’)
For each of the scenarios below, choose the most appropriate method of disinfection or sterilization from the list of options. Each option may be used once, more than once, or not at all.
1 Hand disinfection prior to a surgical operation
2 Treatment of a colonoscope between patients on an endoscopy list
3 Management of a blood spill from a patient thought be hepatitis B- positive
4 Decontamination of a stethoscope following use on a patient positive for methicillinresistant Staphylococcus aureus (MRSA)
5 Treatment of a surgical instrument set used in an appendectomy
Question 2
Option list A Amoxicillin B Ceftazidime C Chloramphenicol D Ciprofloxacin E Flucloxacillin F Gentamicin G Nitrofurantoin H Polymyxin B I Tetracycline J Vancomycin
For each of the following resistance mechanisms, select the one which is most frequently associated with one of the antibiotics in the list of options. Each option may be used once, more than once, or not at all.
- Inactivation by enzymes such as acetyltransferases, phosphotransferases, or adenyltransferases
- Production of an altered DNA gyrase which has reduced affinity for the antibiotic
- Production of a new penicillin-binding protein which has reduced affinity for the antibiotic
4 Inactivation by chromosomally-mediated (constitutive) beta-lactamase enzymes
5 Alteration in the pentapeptide side chain of bacterial peptidoglycan, resulting in failure to bind the antibiotic
Option list A Calymmatobacterium granulomatis B Candida albicans C Chlamydia trachomatis D Cryptococcus neoformans E Haemophilus ducreyi F Herpes simplex virus, type 2 G Human papilloma virus type 6 H Neisseria gonorrhoeae I Treponema pallidum J Trichomonas vaginalis
For each of the following clinical scenarios, select the most likely infecting organism from the list of options. Each option may be used once, more than once, or not at all.
1 A 17 year old heterosexual male presents to his general practitioner with a 24 hour history of painful dysuria and a thin urethral discharge. Nothing abnormal is found on examination. A Gram-stained smear of a uretheral swab shows numerous pus cells and scattered intra-and extra-cellular Gram-negative diplococci.
2 A 30 year old heterosexual male treated for gonococcal urethritis returns to the surgery 5 days later with a relapse of dysuria and urethral discharge. Bacterial culture of a urethral swab is reported as negative.
3 A 38 year old homosexually-active male presents with a painless ulcer at the anal margin. He has had a steady partner for 5 years and not left the UK during the past 2 years, but had receptive anal intercourse with a new partner 3 weeks ago.
4 A 25 year old female presents with a short history of severe vulvo-vaginal inflammation and whitish discharge. She denies having had intercourse for the past month. Two weeks ago she had an episode of dysuria which was treated by her general practitioner with a 5 day course of amoxicillin.
5 A 25 year old woman presents with dysuria and vaginal soreness. She admits to several similar episodes during the past year. On examination the external genitalia show extensive inflammation with a few vesicular lesions on the periphery.
