Comparative susceptibility profile of piperacillin/tazobactam against anaerobic bacteria.

Current data are summarized on the comparative susceptibility of Gram-positive and Gram-negative anaerobic bacteria to piperacillin/tazobactam and other anti-anaerobe agents. For beta-lactamase-positive organisms, tazobactam, in fixed concentration or fixed ratio, lowered the MIC of piperacillin at least four-fold to susceptible levels in almost all cases; beta-lactamase-negative strains were all susceptible to piperacillin alone. Susceptibility rates and MIC90 values for piperacillin/tazobactam were comparable to those of other anti-anaerobe agents, including other combinations of beta-lactam agents with beta-lactamase inhibitors, such as amoxycillin/clavulanate, ticarcillin/clavulanate, ampicillin/sulbactam and cefoperazone/sulbactam. Kinetic studies revealed IC50 and Ki values for tazobactam that were in most cases lower than those of clavulanate and sulbactam against beta-lactamase-positive Gram-negative anaerobic bacilli.