The inhibitory effect of tazobactam on development of piperacillin resistance in Pseudomonas aeruginosa Eto Maki 1 , Futakuchi Naoko 1 , Fukuda Yoshiko 1 , Nomura Nobuhiko 1 , Mitsuyama Junichi 2 , Ishii Yoshikazu 3 1Research Laboratories, Toyama Chemical Co., Ltd 2Development Division, Toyama Chemical Co., Ltd 3Department of Microbiology, Toho University School of Medicine Keyword: Pseudomonas aeruginosa , Tazobactam/piperacillin , 耐性化 pp.126-136
Published Date 2013/9/25
DOI https://doi.org/10.20837/2201310126
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 We investigated the inhibitory effect of tazobactam on development of piperacillin resistance in Pseudomonas aeruginosa. The mutation frequencies of P. aeruginosa cultured in liquid medium were determined after tazobactam/piperacilin or piperacillin exposure. Piperacillin decreased the mutation frequencies to detection limit at 4 MIC, while tazobactam/piperacilin at 2 MIC which is lower concentration than piperacillin. In order to evaluate the effect of tazobactam against clinical isolates in detail, we cultured P. aeruginosa with Etest strips containing tazobactam/piperacillin or piperacillin for two days, then, instead of counting the number of colonies, we measured the inhibition zone of Etests. Since the inhibition zone of tazobactam/piperacillin was larger than that of piperacillin in 64 of 65 clinical isolates, tazobactam was appeared to have the effect to suppress piperacillin resistance. The difference of inhibition zone between these antimicrobials became smaller when they were measured on an agar containing 3-aminophenyl boronic acid. This result suggested that the resistant mechanism of P. aeruginosa exposed to tazobactam/piperacillin or piperacillin was over expression of AmpC. Though we examined ampC trancsriptioal level of P. aeruginosa treated with tazobactam/piperacillin or piperacillin, there was no difference in the transcriptional level between these antimicrobials. It was suggested that the suppression effect of tazobactam on development of resistance is not from the inhibition activity of ampC transcription.


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