Does high level production of SHV-type penicillinase confer resistance to ceftazidime in enterobacteriaceae?

作者：A Petit, H. Ben Yaghlane-Bouslama, Luc Sofer, Roger Labia · 发表于：FEMS Microbiology Letters · 年份：1992 · DOI：10.1111/j.1574-6968.1992.tb05240.x · 被引用次数：20 · 研究领域：Antibiotic Resistance in Bacteria、Bacteriophages and microbial interactions、Salmonella and Campylobacter epidemiology

We report the isolation of a clinical isolate of Klebsiella pneumoniae that showed resistance to ceftazidime (MIC: 8 μg/ml), susceptibility to aztreonam (MIC: 2 μg/ml) and cefotaxime (MIC: 0.015 μg/ml). A synergistic effect between clavulanic acid and ceftazidime or aztreonam against this strain was also observed. The strain hyper-produced SHV-1 penicillinase (990 U/g) which is encoded by a self-transferrable plasmid of at least 150 kb. That the ceftazidime-resistance phenotype could be due to hyperproduction of SHV-1 penicillinase is supported by the study of a spontaneous ceftazidime-resistant mutant in vitro obtained from an Escherichia coli strain containing plasmid p453 encoding the SHV-1. Indeed, this mutant hyperproducing SHV-1 (2200 U/g) was resistant to ceftazidime (MIC: 16 μg/ml) and aztreonam (MIC: 8 μg/ml) but susceptible to cefotaxime (MIC: 0.03 ng/ml). Clavulanic acid showed a synergistic effect when associated with ceftazidime or aztreonam. In contrast, the hyperproduction of TEM-1 (790 U/g) did not confer a ceftazidime- and aztreonam-resistant phenotype while hyperproduction of both TEM-1 and SHV-1 increased the resistance to amoxycillin/clavulanic acid and to cephalothin.