Abstract: Aim To study the antibacterial activity in vitro of cefoperazone/ sulbactam. Methods The MIC₅₀, MIC₉₀ and IC₅₀ of cefoperazone (CPZ), sulbactam (SBT) sulperazone(SPZ) (a combina- tion of CPZ and SBT in a ratio of 1: 1) against 322 strains isolated clinically were determined and analyzed. Results SPZ was more effective than CPZ against the isolates except S. aureus. MIC₉₀ of SPZ to these isolates were reduced to 2 ~ to 4 - fold. MIC₅₀ of SPZ to S. pncumonia and Ⅱ. influenza were reduced remarkly; MICs of SPZ to 53.2 % strains of the family Enter-obacteriaceae and to 40.7 % strains of Ps. auruginosa reduced 2 - fold or more than CPZ. Tolerance to CPZ occurred in 9.04 % strains of the family enterobacteriaceae and in 33.3 % strains of Ps. auruginos and 52.9 % of the fomer and 50.0 % of the latter of CPZ resistant strains were susceptible to SPZ. Although there was almost no antibaterial activity of SBT against the isolates tested, but SBT may enhance the effectivity of CPZ,it may be induced by its inhibitory effect to β-lactamase. Conclusion SPZ may be used in treatment of serious infection caused by CPZ resistant isolates.

Key words: Sulperazone(SPZ), Minimun inhibitory concentration(MIC)