Abstract
Sultamicillin (SBTPC) was found to be widely effective against both gram-positive and gram-negative bacteria, particularly showing the profound activity against β-lactamase-producing ABPC-resistant strains of Staphylococcus spp., E. coli, K. pneumoniae, Proteus spp., H. influenzae and B. fragilis.
The MIC values of SBTPC were scarcely affected by medium pH, inoculum size and concentration of horse serum in the medium.
Bactericidal action of SBTPC was observed at concentrations of around its MIC value.
In mice, the therapeutic effect of orally administered SBTPC was remarkable against various infections caused by ABPC-resistant strains, essentially consistent with the findings in the in vitro antibacterial activity.
The advantages of mutual pro-drug over single ABPC were also observed in the treatment of infections caused by ABPC-sensitive strains. Although SBTPC contains only 58.8% of ABPC in total weight, ED50 values of SBTPC were practically comparable to those of ABPC against infections by ABPC-sensitive isolates of S. aureus and S. pneumoniae.
In mixed infection of ABPC-sensitive S. aureus and APBC-resistant B. fragilis in rat pouches, sulbactam consisting of SBTPC not only potentiated the activity of ABPC against β-lactamase-producing B. fragilis, but kept relatively high level of ABPC in the exudate. As a result SBTPC showed greater bactericidal activity against both B. fragilis and S. aureus than bacampicillin and cefadroxil.
