Comparative in-vitro activity of piperacillin-tazobactam against recent clinical isolates, a Dutch national multicentre study.

In this Dutch national survey piperacillin-tazobactam had a MIC90 of < or = 8 mg/L for Enterobacteriaceae (Enterobacter cloacae excluded) and Pseudomonas aeruginosa, 64 mg/L for E. cloacae, and 4 mg/L for Acinetobacter spp. The corresponding MIC90 values for piperacillin alone were < or = 256 mg/L, 256 mg/L, 16 mg/L and 32 mg/L. Only 15 of 93 piperacillin-tazobactam resistant E. cloacae strains were sensitive for ceftazidime, whereas 41 of 93 ceftazidime-resistant E. cloacae were sensitive to piperacillin-tazobactam.