ANTIBACTERIAL ACTIVITY OF SULBACTAM AND SULBACTAM/CEFOPERAZONE

Abstract

The in vitro antibacterial activity of CPZ against bacteria resistant to CPZ was markedly increased by the addition of Sulbactam (SBT), while the antimicrobial activity of SBT was generally weak, except for its powerful activity against species of N. gonorrhoeae and A. calcoaceticus. The combination of SBT and CPZ in the ratio of 1:1 displayed the marked synergy against β-lactamase-producing strains of E. coli, K. pneumoniae, Proteus spp. and B. fragilis. This synergetic effect was also observed in other species of Enterobacteriaceae, P. aeruginosa and Staphylococcus spp.
The degree of synergetic effect of SBT and CPZ against various species was closely related to the affinity of SBT to the β-lactamase produced by the bacterial strains. The bactericidal activity of CPZ was also potentiated by the addition of SBT.
The in vitro and in vivo antibacterial activities of various ratios of SBT and CPZ were compared using CPZresistant E. coli, K. pneumoniae, Proteus spp. and B. fragilis, and the most effective ratio in in vitro was found to be between 1:4 and 4:1, while the ratio between 1:8 and 2:1 was most effective against experimental infections in mice.
The simultaneous administration of SBT and CPZ to the mice infected with various CPZ-resistant bacteria demonstrated higher survival rate of mice than that by CPZ administration alone, and the administration of SBT 60 min. prior to that of CPZ showed full survival without lowering of the survival rate of mice.