1. A 4-year-old child presents with a 2-week history of persistent cough, worsening at night and followed by vomiting. The child is unvaccinated, and pertussis is clinically suspected. What is the most appropriate next step in management?

• Start clarithromycin and notify public health authorities
• Isolate the child at home for 14 days and monitor symptoms
• Administer the pertussis vaccine immediately
• Treat only household contacts with antibiotics

Answer: Start clarithromycin and notify public health authorities

Clarithromycin is the first-line treatment for pertussis in children. Additionally, pertussis is a notifiable disease in the UK, so public health authorities must be informed to manage and prevent further spread.

2. A 50-year-old man presents with bilateral ptosis, dysarthria, and progressive muscle weakness. He recently ate home-canned food. What is the most appropriate initial management?

• Administer botulinum antitoxin
• Prescribe high-dose IV antibiotics
• Perform gastric lavage
• Start IV steroids

Answer: Administer botulinum antitoxin

Botulinum antitoxin is critical for preventing further toxin binding and reducing severity of botulism symptoms.

3. What is the primary mechanism by which HIV causes immunodeficiency?

• Direct destruction of CD4+ T cells
• Suppression of bone marrow function
• Inhibition of antigen presentation by dendritic cells
• Autoimmune destruction of lymphocytes

Answer: Direct destruction of CD4+ T cells

HIV infects and destroys CD4+ T lymphocytes, leading to profound immunodeficiency and opportunistic infections.

4. A 65-year-old woman presents with diarrhoea following a course of antibiotics. Stool tests are positive for C. difficile toxin. What is the most appropriate first-line treatment?

• Oral vancomycin
• Metronidazole IV
• Loperamide
• Oral ciprofloxacin

Answer: Oral vancomycin

For an initial episode of C. difficile (mild or severe), oral vancomycin is the recommended first-line treatment per current guidelines.

5. A 25-year-old traveller returning from sub-Saharan Africa presents with fever, chills, and headache. Thick and thin blood films confirm Plasmodium falciparum. What is the most appropriate initial treatment?

• IV artesunate
• Oral hydroxychloroquine
• Start doxycycline monotherapy
• Oral mefloquine

Answer: IV artesunate

Severe or complicated falciparum malaria requires IV artesunate, which is more effective and safer than IV quinine.

6. A 2-year-old boy presents with fever, cough, conjunctivitis, and a maculopapular rash. Koplik spots are visible on examination. What is the most effective way to prevent measles outbreaks?

• Administer the MMR vaccine to all susceptible individuals
• Isolate the child for 7 days after rash onset
• Provide immune globulin to exposed contacts
• Start prophylactic antibiotics for close contacts

Answer: Administer the MMR vaccine to all susceptible individuals

MMR vaccination is the cornerstone of measles prevention, ensuring herd immunity and reducing outbreaks.

7. A 50-year-old man presents with severe pain, swelling, and erythema of the leg. The skin is dusky, and crepitus is present. What is the most appropriate next step?

• Immediate surgical debridement
• Start broad-spectrum IV antibiotics
• Perform MRI to confirm the diagnosis
• Administer IV steroids

Answer: Immediate surgical debridement

Necrotising fasciitis is a surgical emergency; rapid debridement plus broad-spectrum antibiotics are vital to prevent mortality.

8. What is the most common complication of infectious mononucleosis caused by EBV?

• Splenic rupture
• Hepatitis
• Haemolytic anaemia
• Airway obstruction due to tonsillar swelling

Answer: Hepatitis

Mild hepatitis is often seen with EBV infection. Other issues like splenic rupture or airway problems occur less frequently.

9. A 6-year-old boy presents with perianal itching, worse at night. His mother notices small white worms in his stool. What is the most appropriate treatment?

• Mebendazole for the whole family
• Topical antihistamine cream
• Oral ivermectin
• Observation and reassurance

Answer: Mebendazole for the whole family

Threadworms (Enterobius vermicularis) require mebendazole or similar plus treating close contacts to prevent reinfection.

10. A 7-year-old girl presents with fever, a red "strawberry" tongue, and a fine, sandpaper-like rash. Throat swab confirms Group A Streptococcus. What is the most appropriate treatment?

• Penicillin V
• Erythromycin
• Amoxicillin
• Ceftriaxone

Answer: Penicillin V

Scarlet fever is best treated with oral Penicillin V (phenoxymethylpenicillin) for a full course to prevent complications.