Optimal Duration of Therapy for Brucellosis
The optimal duration of therapy for this patient with uncomplicated brucellosis is 6 weeks (Answer B). 1, 2, 3
Treatment Regimen and Duration
For uncomplicated brucellosis, all standard first-line regimens require 6 weeks of treatment:
Doxycycline-Streptomycin (DOX-STR): Doxycycline 100 mg twice daily orally for 6 weeks PLUS streptomycin 15 mg/kg daily intramuscularly for 2-3 weeks (AI recommendation - considered the gold standard with lowest relapse rates) 1, 2, 3
Doxycycline-Rifampicin (DOX-RIF): Doxycycline 100 mg twice daily orally for 6 weeks PLUS rifampicin 600-900 mg daily as a single morning dose for 6 weeks (AI recommendation) 1, 2, 3
Doxycycline-Gentamicin (DOX-GENT): Doxycycline 100 mg twice daily orally for 6 weeks PLUS gentamicin 5 mg/kg daily parenterally for 7 days (BI recommendation) 1, 2
Clinical Context for This Patient
This patient presents with classic uncomplicated brucellosis features:
- Raw milk ingestion (primary transmission route) 4, 5
- Systemic symptoms (fever, fatigue, malaise, arthralgia, back pain) 4, 5
- Mild hepatosplenomegaly (common finding) 4, 5
- Gram-negative coccobacilli on blood culture (consistent with Brucella species) 4, 5
The back pain warrants careful attention - while this could represent simple arthralgia, brucellar spondylitis (vertebral osteomyelitis) is the most common complication of brucellosis and would require extended treatment duration beyond 6 weeks. 1, 3 If MRI demonstrates spinal involvement, treatment duration should be extended to 12 weeks (3 months) with aminoglycoside-containing regimens potentially superior to rifampicin-containing ones. 1, 6, 3
Important Caveats
Without evidence of complications, 6 weeks is the standard duration:
- Relapse rates with appropriate 6-week treatment range from 5-15%, and relapses are typically mild and respond to the same regimens 2, 3
- Shorter durations (3 weeks) are inadequate and associated with unacceptably high relapse rates 1
- Longer durations (12 or 24 weeks) are reserved for complicated brucellosis such as spondylitis, endocarditis, or neurobrucellosis 1, 6, 3
Critical pitfall to avoid: Do not assume uncomplicated disease if back pain is present - obtain MRI of the spine to exclude brucellar spondylitis, which would necessitate 12-week treatment duration. 1, 6, 3