Comparison of the efficacy of gentamicin for 5 days plus doxycycline for 8 weeks versus streptomycin for 2 weeks plus doxycycline for 45 days in the treatment of human brucellosis: a randomized clinical trial.

Objectives: To compare the efficacy of gentamicin for 5 days plus doxycycline for 8 weeks with streptomycin for 2 weeks plus doxycycline for 45 days in the treatment of human brucellosis.

Methods: In each arm of the study, 82 patients older than 10 years randomly received 5 mg/kg gentamicin once daily for 5 days plus 100 mg of doxycycline twice daily for 8 weeks or 1 g of streptomycin intramuscularly for 2 weeks plus the same dose of doxycycline for 45 days. Therapeutic failure and relapse in these two treatment groups were compared. This study was registered in the Iranian Registry of Clinical Trials (www.irct.ir) with registration number ID: IRCT138708191441N1.

Results: The clinical manifestations in these two groups were similar. Therapeutic failure was seen in two (2.4%) patients in the gentamicin/doxycycline group and in four (4.9%) patients in the streptomycin/doxycycline group [relative risk (RR) = 0.5, 95% confidence interval (CI) 0.09-2.66, P = 0.68]. Relapse was seen in two (2.4%) cases in the gentamicin/doxycycline group and in five (6.1%) cases in the streptomycin/doxycycline group (RR = 0.4, 95% CI 0.08-2, P = 0.44). The efficacy with the gentamicin/doxycycline regimen was 95.12% and that with the streptomycin/doxycycline regimen was 89% (RR = 1.07, 95% CI 0.98-1.17, P = 0.25). Cox regression analyses showed no differences among the two treatment groups for patients who had relapse or therapeutic failure and those who had not regarding baseline covariates such as sex, duration of disease before diagnosis, positive blood culture and focal disease.

Conclusions: The results show that the efficacy of gentamicin for 5 days plus doxycycline for 8 weeks is not superior to that of streptomycin for 2 weeks plus doxycycline for 45 days.