Brucellosis — DTM&H MCQ
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Correct answer: E — Doxycycline for 6 weeks plus gentamicin for 7 days
The correct answer is E, doxycycline for 6 weeks plus gentamicin for 7 days. This patient has classic brucellosis (occupational exposure to livestock as a veterinarian, undulant fever, sacroiliitis, hepatosplenomegaly, positive blood cultures after prolonged incubation), and combination therapy is required because Brucella is a facultative intracellular organism that readily relapses if treated inadequately. Doxycycline provides prolonged tissue and intracellular penetration over the 6 week course, while a short course of an aminoglycoside (gentamicin) covers the initial bacteraemic phase and reduces relapse rates compared with tetracycline monotherapy. This doxycycline plus gentamicin regimen has been shown to give total treatment failure rates comparable to, or better than, the classic doxycycline plus streptomycin combination, and gentamicin is more practical in most UK and field settings than streptomycin. Why the other options are wrong: A. Ciprofloxacin for 14 days: fluoroquinolone monotherapy for only 2 weeks is too short and has unacceptably high relapse rates in brucellosis; quinolones are only used as part of combination regimens and even then are second line. C. Rifampicin monotherapy for 6 weeks: single agent therapy fails to sterilise the intracellular reservoir and is associated with high relapse and emergence of rifampicin resistance. B. Co-trimoxazole for 4 weeks: not a recommended first line agent for brucellosis in adults; it is reserved as an alternative agent in pregnancy or children under 8, and even then given in combination, not alone. D. Ceftriaxone for 14 days: cephalosporins have poor intracellular activity against Brucella and clinical response is inconsistent; ceftriaxone is not part of standard first line regimens and a 14 day course is too short. Key point: Brucellosis always requires combination therapy for a minimum of 6 weeks, with doxycycline plus gentamicin (7 days) or doxycycline plus streptomycin as first line, because monotherapy or short courses carry unacceptable relapse rates.
Reference: GPnotebook, Brucellosis: Treatment, first line regimen doxycycline plus gentamicin/streptomycin for 6 weeks, https://gpnotebook.com/pages/infectious-disease/brucellosis/treatment