In vitro antimicrobial susceptibility of Brucella species.

MIC50 and MIC90 values of doxycycline, rifampicin, ciprofloxacin, trimethoprim-sulphamethoxazole and ceftriaxone for 42 blood isolates of Brucella species were determined using the Etest. Thirty-seven isolates were identified as B. melitensis and five as B. abortus. Doxycycline had the lowest and rifampicin the highest MIC50 values. Four strains were non-susceptible to rifampicin, and one strain was resistant to trimethoprim-sulphamethoxazole. There is no significantly important resistance problem for antibiotics targeted against Brucella species in Turkey. However, since rifampicin is commonly used for prevalent diseases such as tuberculosis, the regional susceptibility pattern of rifampicin should be assessed periodically.