The in vitro effect of some antibiotic combinations including ofloxacin and ciprofloxacin against brucella melitensis

Objective: To determine the in vitro activity and place of fluoroquinolones in combination therapy of brucellosis and to compare these results with the results of doxycycline plus rifampicin combination which is the current regimen of therapy. Method: Eight blood isolates of Brucella melitensis were used. Minimal inhibitory concentration (MIC) values of doxycycline, rifampicin, ofloxacin and ciprofloxacin were determined by agar dilution method and the effect of combination was tested by simplified checkerboard method. Results: The MIC values for doxycycline, rifampicin, ofloxacin and ciprofloxacin were found as 1.0, 4.0, 0.5 and 1.0 pg/ml respectively. The effect of combination of ofloxacin with doxycycline or rifampicin was found to be indifferent, when combinations of ciprofloxacin with doxycycline or rifampicin and doxycycline with rifampicin were additive. Conclusion: These results may encourage clinical use of a fluoroquinolone in the combination therapy of brucellosis.