Multiple Choice Questions MCQ

Question 59# Print Question

A 34-year-old HIV positive man is being treated for Pneumocystis carinii pneumonia with cotrimoxazole. Arterial blood gases show a pO2 of 8.2 kPa.

What drug should be added to treatment?

A. Meropenem

B. Chloramphenicol

C. Steroids

D. Nebulized fluconazole

E. Magnesium sulphate

Question 56# Which of the following is true regarding the Salmonella species?
A. Rose spots appear in all patients with typhoid
B. They are normally present in the gut as commensals
C. They are anaerobic organisms
D. A relative bradycardia is often seen in typhoid fever
E. Salmonella typhi can be categorized into type A, B and C
Correct Answer D: Salmonella: The Salmonella group contains many members, most of which cause diarrhoeal diseases. They are aerobic, Gram negative rods which are not normally present as commensals in the gut. Typhoid and paratyphoid are caused by Salmonella typhi and Salmonella paratyphi (types A, B & C) respectively. They are often termed enteric fevers, producing systemic symptoms such as headache, fever, arthralgia. Features: Initially systemic upset as above Relative bradycardia Abdominal pain, distension Constipation: although Salmonella is a recognized cause of diarrhoea, constipation is more common in typhoid Rose spots: present on the trunk in 40% of patients, and are more common in paratyphoid Possible complications include: Osteomyelitis (especially in sickle cell disease where Salmonella is one of the most common pathogens) GI bleed/perforation Meningitis Cholecystitis Chronic carriage (1%, more likely if adult females)

Question 57# Which one of the following is true regarding Escherichia coli infection?
A. It is a Gram negative coccus
B. E coli is an important cause of neonatal meningitis
C. The O157:H7 strain is typically spread via shellfish
D. Severe infection should be treated with teicoplanin
E. It is an aerobic bacteria
Correct Answer B: Escherichia coli is classified as a facultative anaerobe. Escherichia coli: Escherichia coli is a facultative anaerobic, lactose-fermenting, Gram negative rod which is a normal gut commensal. E coli infections lead to a variety of diseases in humans including: Diarrhoeal illnesses UTIs Neonatal meningitis

Question 58# A 34-year-old man presents with a widespread maculopapular rash and mouth ulcers. Two months ago he presented to the local GUM clinic after developing a painless penile ulcer. At the time he was noted to have inguinal lymphadenopathy. Which one of the following organisms is most likely to be responsible?
A. Lymphogranuloma venereum
B. Herpes simplex virus type 2
C. Mycoplasma genitalium
D. Haemophilus ducreyi
E. Treponema pallidum
Correct Answer E: This patient has symptoms of secondary syphilis. Syphilis: Syphilis is a sexually transmitted infection caused by the spirochete Treponema pallidum. Infection is characterized by primary, secondary and tertiary stages. The incubation period is between 9-90 days. Primary features: Chancre - painless ulcer at the site of sexual contact Local lymphadenopathy Often not seen in women (the lesion may be on the cervix) Secondary features - occurs 6-10 weeks after primary infection: Systemic symptoms: fevers, lymphadenopathy Rash on trunk, palms and soles Buccal 'snail track' ulcers (30%) Condylomata lata Tertiary features: Gummas Aortic aneurysms General paralysis of the insane Tabes dorsalis

Question 60# What is the mechanism of action of the antiviral agent ribavirin?
A. Inhibits DNA polymerase
B. Inhibits uncoating of virus in the cell
C. Protease inhibitor
D. Nucleoside analogue reverse transcriptase inhibitor
E. Interferes with the capping of viral mRNA
Correct Answer E: Antiviral agents: Aciclovir: Aciclovir is phosphorylated by thymidine kinase which in turn inhibits the viral DNA polymerase Ribavirin: Effective against a range of DNA and RNA viruses Interferes with the capping of viral mRNA Interferons: Inhibit synthesis of mRNA, translation of viral proteins, viral assembly and release Amantadine: Used to treat influenza Inhibits un-coating of virus in cell Anti-retroviral agent used in HIV: Nucleoside analogue reverse transcriptase inhibitors (NRTI) Examples: zidovudine (AZT), didanosine, lamivudine, stavudine, zalcitabine Protease inhibitors (PI): Inhibits a protease needed to make the virus able to survive outside the cell Examples: indinavir, nelfinavir, ritonavir, saquinavir Non-nucleoside reverse transcriptase inhibitors (NNRTI): Examples: nevirapine, efavirenz

Question 59# A 34-year-old HIV positive man is being treated for Pneumocystis carinii pneumonia with cotrimoxazole. Arterial blood gases show a pO2 of 8.2 kPa. What drug should be added to treatment?
A. Meropenem
B. Chloramphenicol
C. Steroids
D. Nebulized fluconazole
E. Magnesium sulphate
Correct Answer C: HIV: Pneumocystis jiroveci pneumonia: Whilst the organism Pneumocystis carinii is now referred to as Pneumocystis jiroveci, the term Pneumocystis carinii pneumonia (PCP) is still in common use: Pneumocystis jiroveci is an unicellular eukaryote, generally classified as a fungus but some authorities consider it a protozoa PCP is the most common opportunistic infection in AIDS All patients with a CD4 count < 200/mm³ should receive PCP prophylaxis Features: Dyspnoea Dry cough Fever Very few chest signs Extrapulmonary manifestations are rare (1-2% of cases), may cause: Hepatosplenomegaly Lymphadenopathy Choroid lesions Investigation: CXR: typically shows bilateral interstitial pulmonary infiltrates but can present with other x-ray findings e.g. lobar consolidation. May be normal Exercise-induced desaturation Sputum often fails to show PCP, bronchoalveolar lavage (BAL) often needed to demonstrate PCP (silver stain) Management: Co-trimoxazole IV pentamidine in severe cases Steroids if hypoxic (if pO₂ < 9.3kPa then steroids reduce risk of respiratory failure by 50% and death by a third)