Bacterial susceptibilities to piperacillin/tazobactam in a tertiary care hospital: 5-year review.

Several factors influence the speed of development of antibacterial resistance, among which is the amount of antibiotic consumption. During the 3-year period 1998-2000, the consumption of piperacillin/tazobactam (pip/tazo) increased by 85% in our hospital. Five years ago we conducted a comparative in vitro study to evaluate susceptibilities of microorganisms to pip/tazo. The objective of the present study was to re-evaluate in vitro susceptibilities to pip/tazo, compared to other beta-lactams, and the potential impact its increased consumption might have on its susceptibility patterns. The study was performed between November 2000 and April 2001. As in 1996, of the beta-lactams studied, pip/tazo and imipenem had the highest susceptibility rates against selected pathogens (>90% susceptibility rates). P. aeruginosa susceptibilities to both imipenem and pip/tazo were high (97% for both). P. aeruginosa susceptibilities to cefepime were lower. Despite its increased use, pip/tazo retained its initially observed high susceptibility rates for the study pathogens.