OBJECTIVE: To evaluate the in-vitro
antibacterial activity of combinations of cefoperazone(CPZ)-tazobactam(TAZ) according
to ratio 8:1 and factors of impact on
antibacterial achvity. METHODS: The minimal inhibitory concentrations (MICs) of CPZ/TAZ (8:l) to the bacteria isolated from clinical department and producing B-actamases were determined by standard agar dilution method and compared with the MICs of CPZ,
cefoperazone (CPZ)/sulbactam (SUB) (l:1) and piperacillin (PIPC)/TAZ) (8:1). RESULTS: The antibacterial activity of CPZ combined with TAZ was superior to CPZ alone and similar to CPZ/SUB(1:1) and PIPC/TAZ(8: 1). The result of in-vitro bactericidal activity showed the minimal bactericidal concentrations (MBC90) of CPZ/TAZ of 8:1 were 4 to 8 higher than MIC90 against the detected bacteria. The MIC of CP/TAZ (8:1) increased with increase of concentration of serum albumin and bacteria incubated in media. The MICs of CPZ/TAZ (8:1) to MSSA and MSCoNS increased and The MICs of it against gram-negative bacilli decreased with increase of pH in media. CONCLUSION: The stability of the combinations of CPZ with TAZ to B-lactamases is improved and antibacterial and bactericidal activities are of cefoperazone enhanced by tazobactam. Different condihons in media can influence on antimicrobial activity of CPNAZ.