Optimal Duration of Therapy for Acute Brucellosis
The optimal duration of antimicrobial therapy for this patient with acute uncomplicated brucellosis is 6 weeks (Answer B). 1, 2
Treatment Duration Rationale
Standard treatment for uncomplicated brucellosis requires a 6-week regimen of doxycycline (100 mg twice daily) combined with either streptomycin (1 g daily) for 2-3 weeks or rifampicin (600-900 mg daily) for the full 6 weeks. 1, 2 This duration has been established by the World Health Organization and represents the evidence-based standard for achieving cure while minimizing relapse risk. 1
Clinical Context Supporting 6-Week Duration
This patient presents with classic acute brucellosis features:
- Fever, malaise, arthralgia, and back pain are characteristic presenting symptoms 2, 3
- Hepatosplenomegaly is present in 31-55% of pediatric and adult cases 3
- Raw milk ingestion is the primary transmission route 4, 3
- Gram-negative coccobacilli on blood culture confirms the diagnosis 2
- Mild anemia and thrombocytopenia are common non-specific findings in 64-65% of cases 3, 5
Importantly, there is no evidence of complicated disease (no spondylitis mentioned despite back pain, no neurobrucellosis, no endocarditis), which would require longer treatment duration. 2
Why Not Other Durations?
- 3 weeks (Option A): Too short and associated with significantly higher relapse rates, particularly when single-drug therapy or inadequate duration is used 3
- 12 weeks (Option C): Reserved for complicated cases such as neurobrucellosis, endocarditis, or spondylitis requiring extended therapy 2, 5
- 24 weeks (Option D): This represents the surveillance period for exposed individuals, not the treatment duration for active disease 6
Expected Outcomes with 6-Week Treatment
- Relapse rates of 5-15% are expected even with appropriate 6-week treatment 1, 2
- Clinical improvement should occur within 7-14 days, with fever typically resolving in 3-4 days 2, 3
- Relapses are usually mild and respond to the same treatment regimens 1, 2
- Cure rates exceed 90% when combination therapy is used for the full 6-week duration 4, 7
Critical Treatment Considerations
The specific antibiotic combination matters as much as duration: Doxycycline plus streptomycin has the lowest relapse rate, while doxycycline plus rifampicin is equally effective and more practical given streptomycin's limited availability. 1 Single-drug therapy or shorter courses are associated with relapse rates approaching 50%. 7