RESUMEN
Recently, two new combinations of ß-lactam antibiotics with ß-lactamase inhibitors become commercially avaiable in Brazil: piperacillin/tazobactam and ampicillin/sulbactam. This study was designed to assess and compare the in-vitro activity of theses new compounds, as well as that of ticarcillin/clavulanic acid, against bacteria isolated in our environment. A total of 749 bacteria isolated at São Paulo Hospital were tested using the disk diffusion method, in compliance with NCCLS Standardization, using strict quality control. Only one sample per patient was included in the study. Oxacillin-resistant staphylococcus samples were not included in this study. Of the total samples tested 84.5 percent were susceptible to piperacillin/tazobactam, 81.2 percent to ticarcillin/clavulanic acid, and 77.6 percent to ampicillin/sulbactam. Piperacillin/tazobactam was also found to be the most active combination of the three against Enterobacteriaceae (n=312), inhibiting 91.7 percent of the bacteria tested. Ticarcillin/clavulanic acid was active against 85.8 percent of the Enterobacteriaceae, while ampicillin/sulbactam inhibited 83.2 percent of the samples...