[In vitro interaction of tazobactam/piperacillin combined with aminoglycosides against Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli AND Staphylococcus aureus].

The in vitro combination effect of tazobactam/piperacillin (TAZ/PIPC) with aminoglycosides (amikacin (AMK) and isepamicin (ISP)) were investigated by the checkerboard dilution method against PIPC-resistant and TAZ/PIPC-susceptible Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Methicillin-sensitive Staphylococcus aureus (MSSA). The following results were obtained. 1. The combination of TAZ/PIPC with AMK showed synergistic effect for 66.7% of P. aeruginosa and 9.1% of K. pneumoniae and additive effect for 76.9% of E. coli and 74.1% of MSSA. The antagonistic effect of TAZ/PIPC with AMK was not demonstrated for all tested strains. 2. The combination of TAZ/PIPC with ISP showed synergistic effect for 61.9% of P. aeruginosa and 22.7% of K. pneumoniae and additive effect for 84.6% of E. coli and 66.7% of MSSA. The antagonistic effect of TAZ/PIPC with ISP was not demonstrated for all tested strains. In conclusion, these results suggest that the combination therapies of TAZ/PIPC with aminoglycosides are useful for the clinical treatment of sepsis caused by above four species.