In-vitro activity of ciprofloxacin, ceftriaxone and five other antimicrobial agents against 95 strains of Brucella melitensis.

We studied the in-vitro activity of seven antibiotics against 95 strains of Brucella melitensis isolated in blood cultures of 95 patients with brucellosis. The minimum inhibitory concentration (MIC) was measured by the agar dilution method. All strains of B. melitensis were inhibited by doxycycline at 0.25 mg/l, tetracycline at 0.5 mg/l, ciprofloxacin at 0.5 mg/l, streptomycin at 1 mg/l, ceftriaxone at 1 mg/l, rifampicin at 4 mg/l and by co-trimoxazole at 0.5/9.5 mg/l. We did not find strains resistant to any of the antibiotics studied. All antibiotics, including ciprofloxacin and ceftriaxone, showed a good in-vitro activity against B. melitensis.