MRCP Part 1 Infectious Diseases and Immunology

Question 1

A 30-year-old man from sub-Saharan Africa presents with fever, weight loss, and a CD4 count of 150 cells/microL.
Chest X-ray shows bilateral upper lobe cavitating lesions.
Sputum is positive for acid-fast bacilli.
What is the most appropriate initial treatment regimen?

Accepted Answer

Rifampicin, isoniazid, pyrazinamide, and ethambutol for 2 months then rifampicin and isoniazid for 4 months

Answer

Rifampicin and isoniazid for 6 months

Answer

Isoniazid monotherapy for 9 months

Answer

Levofloxacin and amikacin for 3 months

Question 2

A healthcare worker sustains a needlestick injury from a patient known to be HIV positive with a detectable viral load. The injury is deep and from a hollow-bore needle. When should post-exposure prophylaxis (PEP) ideally be started?

Accepted Answer

Within 1 hour (as soon as possible)

Answer

Within 24 hours

Answer

Within 72 hours

Answer

Within 1 week

Question 3

A 5-year-old child presents with fever, petechial rash, and neck stiffness. CSF shows raised WCC (predominantly neutrophils), raised protein, low glucose, and Gram-negative diplococci. What is the most likely causative organism?

Accepted Answer

Neisseria meningitidis

Answer

Streptococcus pneumoniae

Answer

Haemophilus influenzae

Answer

Listeria monocytogenes

Question 4

A patient with rheumatoid arthritis on methotrexate and adalimumab develops reactivation of latent tuberculosis. Which component of the immune system has been most critically compromised?

Accepted Answer

TNF-alpha mediated macrophage activation and granuloma maintenance

Answer

B-cell antibody production

Answer

Complement activation

Answer

Natural killer cell function

Question 5

A 70-year-old man develops profuse watery diarrhoea and abdominal cramping 5 days after completing a course of co-amoxiclav. Stool toxin assay is positive. What is the first-line treatment?

Accepted Answer

Oral vancomycin

Answer

Oral metronidazole

Answer

IV vancomycin

Answer

Fidaxomicin

Question 6

A patient presents with a painless genital ulcer. Dark-field microscopy of the ulcer exudate shows spirochaetes. What is the recommended treatment?

Accepted Answer

Intramuscular benzathine penicillin G (single dose)

Answer

Oral doxycycline for 14 days

Answer

Oral azithromycin 1g single dose

Answer

Topical aciclovir

A 30-year-old man from sub-Saharan Africa presents with fever, weight loss, and a CD4 count of 150 cells/microL.Chest X-ray shows bilateral upper lobe cavitating lesions.Sputum is positive for acid-fast bacilli.What is the most appropriate initial treatment regimen?

A 30-year-old man from sub-Saharan Africa presents with fever, weight loss, and a CD4 count of 150 cells/microL.
Chest X-ray shows bilateral upper lobe cavitating lesions.
Sputum is positive for acid-fast bacilli.
What is the most appropriate initial treatment regimen?