Brucellosis — DTM&H MCQ

Correct answer: B — Doxycycline plus rifampicin

Doxycycline plus rifampicin (option B) is correct. The vignette describes brucellosis: undulating fever, night sweats, back pain (spondylitis is a classic complication), Middle Eastern exposure, unpasteurised goat milk, and blood cultures growing small Gram-negative coccobacilli (Brucella spp). Brucella is an intracellular organism, so single-agent therapy fails to eradicate it and is associated with high relapse rates. UK reference laboratory guidance (UKHSA) and WHO-aligned practice recommend combination therapy, typically oral doxycycline plus rifampicin for six weeks, to achieve cure and minimise relapse. Why the other options are wrong: C. Doxycycline for one day: this is the regimen for louse-borne relapsing fever or as chemoprophylaxis, not brucellosis; brucellosis needs weeks of combination therapy, not a single dose. D. Cefalexin: a cephalosporin has poor intracellular penetration and is not an evidence-based agent for Brucella; it has no role in first-line treatment. E. Chloroquine: this is an antimalarial with no activity against Brucella; malaria does not explain a positive Gram-negative coccobacillus culture or the exposure history described. A. Praziquantel: this is an antihelminthic used for schistosomiasis and other flukes or tapeworms; it has no antibacterial activity and is irrelevant to a bacteraemic illness. Key point: unpasteurised dairy exposure plus undulating fever and Gram-negative coccobacilli on culture points to brucellosis, which requires prolonged combination antibiotic therapy (doxycycline plus rifampicin) because Brucella is intracellular and monotherapy relapses.

Reference: UKHSA, Brucella: laboratory and clinical services, dosage guidance: oral doxycycline plus rifampicin for 6 weeks in patients aged 12 years or older, gov.uk/guidance/bru-reference-services