In vitro antibacterial activities of different formula cefotaxime/sulbactam

Objective To study the in vitro antibacterial activities of cefotaxime and different formula of cefotaxime/sulbactam.Methods Minimal inhibitory concentrations (MIC)and the minimal bactericidal concentrations(MBC) were measured on 644 clinical isolates. The influences of the inoculum size,pH and concentrtion of serum protein on antibacterial activities of cefotaxime/sulbactam were observed. Results MIC_ 50 of cefotaxime/sulbactam(1∶1,2∶1) against β-lactmases-producing gram-positive coccus was 0.06～32 mg·L -1 , MIC_ 90 of cefotaxime/sulbactam(1∶1,2∶1) against gram-negative bacteria was 0.25～32 mg·L -1 ,being 1/4～1/8 of that of cefotaxime alone.Conclusion Cefotaxime/sulbactam with 1∶1and 2∶1 ratio possesses high antibacterial activities against most clinical isolates. It's better than that of cefotaxime alone and cefotaxime/sulbactam with other ratios.