What is the first-line treatment for brucellosis in a 48-year-old male with fever, headache, back pain, and splenomegaly after consuming unpasteurized milk?

Treatment of Brucellosis

The first-line treatment for brucellosis in this 48-year-old male with fever, headache, back pain, and splenomegaly after consuming unpasteurized milk is doxycycline plus streptomycin (option C). 1, 2

Recommended Treatment Regimen

The optimal regimen consists of:

• Doxycycline: 100 mg twice daily orally for 6 weeks
• Streptomycin: 15 mg/kg daily intramuscularly for 2-3 weeks

This combination is considered the first-line regimen with the highest level of evidence (AI) according to current guidelines 1. It demonstrates superior efficacy compared to other combinations, particularly in preventing relapse.

Evidence Supporting This Recommendation

The doxycycline-streptomycin (DOX-STR) regimen is superior to doxycycline-rifampicin (DOX-RIF) for several reasons:

• A Cochrane systematic review found that DOX-STR is more effective than DOX-RIF with significantly lower treatment failure rates (RR 1.91,95% CI 1.07 to 3.42) 2
• DOX-STR has a lower relapse rate compared to DOX-RIF (RR 2.39,95% CI 1.17 to 4.86) 2
• DOX-STR produces fewer minor adverse drug reactions than DOX-RIF 2

Alternative Regimens

If streptomycin is unavailable or contraindicated, the following alternatives can be considered:

1. Doxycycline-Gentamicin (DOX-GENT):

   • Doxycycline: 100 mg twice daily orally for 6 weeks
   • Gentamicin: 5 mg/kg daily parenterally for 7 days
   • Evidence level: BI 1

2. Doxycycline-Rifampicin (DOX-RIF):

   • Doxycycline: 100 mg twice daily orally for 6 weeks
   • Rifampicin: 600-900 mg daily for 6 weeks
   • Evidence level: AI, but with higher relapse rates 1

Treatment Duration and Monitoring

• For uncomplicated brucellosis: minimum 6 weeks of treatment
• For complicated cases with spinal involvement or abscesses: 3-6 months 1, 3
• Regular clinical monitoring is essential during treatment
• Follow-up for at least 2 years after treatment completion is recommended to detect potential relapses 1

Important Considerations

• Streptomycin requires daily intramuscular injections, which may impact treatment choice based on access to care and cost 2
• Treatment should begin promptly after diagnosis to prevent complications
• Relapse rates are significantly higher with monotherapy (13% vs. 4.8%) and short-term treatment regimens (less than 4 weeks) (22% vs. 4.8%) 4
• In patients with neurobrucellosis or spinal involvement, treatment duration may need to be extended to 3-6 months 1, 3

The evidence clearly supports doxycycline plus streptomycin as the most effective regimen for treating brucellosis in this patient, with the lowest rates of treatment failure and relapse compared to other combinations.