Multicenter evaluation of the in vitro activity of six broad-spectrum β-lactam antimicrobial agents in Puerto Rico

The minimum inhibitory concentrations of 6 broad-spectrum beta-lactam antimicrobial agents were determined by use of the Etest versus a total of 569 bacteria in 7 Puerto Rican hospital laboratories. These included 342 recent clinical isolates of Enterobacteriaceae, 63 Pseudomonas aeruginosa, 54 Acinetobacter species, and 110 oxacillin-susceptible staphylococci. Extended spectrum beta-lactamase production was noted an-long 11% of Klebsiella pneumoniae isolates, Hyperproduction of Amp C cephlosporinase was observed with > 20% of isolates of Enterobacter spp., Serratia spy., and Citrobacter freundii. The overall rank order of activity of the six beta-lactams examined in this study versus all clinical isolates was imipenem (95.8% susceptible) > cefepime (91.1%) > piperacillin/tazobactam (82.3%) > cefotaxime (77.6%) > piperacillin (72.5%) > ceftazidime (67.0%). (C) 1998 Elsevier Science Inc.