Novel plasmid-mediated beta-lactamase in clinical isolates of Klebsiella pneumoniae more resistant to ceftazidime than to other broad-spectrum cephalosporins
Novel plasmid-mediated beta-lactamase in clinical isolates of Klebsiella pneumoniae more resistant to ceftazidime than to other broad-spectrum cephalosporins
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肺炎克雷伯菌临床分离株中新型质粒介导的β-内酰胺酶对头孢他啶比对其他广谱头孢菌素更耐药
DOI：
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发表时间：
1988
影响因子：
4.9
通讯作者：
R. Cluzel
中科院分区：
文献类型：
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作者：
A. Petit;D. Sirot;C. Chanal;J. Sirot;R. Labia;G. Gerbaud;R. Cluzel
多重耐药肺炎克雷伯菌菌株分离自同一重症监护病房的3例患者，对头孢他啶的耐药性高于头孢噻肟和氨曲南，但对氧内酰胺和亚胺培南仍敏感。对β-内酰胺类、卡那霉素、链霉素、磺胺类和四环素类的耐药性可通过接合转移至大肠杆菌，并在用溴化乙锭处理后整体丧失。琼脂糖凝胶电泳的野生型和transconjugants表明，这些电阻介导的150-脱氢酶质粒，pCFF 14。菌株组成型产生β-内酰胺酶，其等电点接近5.6，并且头孢他啶和头孢噻吩的Vmax高于头孢噻肟。因此，这种酶的底物分布和等电点不同于其他已知质粒介导的β-内酰胺酶，包括广谱酶CTX-1。杂交研究支持从TEM型β-内酰胺酶衍生的新酶。
Multiresistant Klebsiella pneumoniae strains isolated from three patients in the same intensive care unit were more resistant to ceftazidime than to cefotaxime and aztreonam but remained susceptible to moxalactam and imipenem. Resistance to beta-lactams, kanamycin, streptomycin, sulfonamides, and tetracyclines was transferable to Escherichia coli by conjugation and was lost en bloc after treatment with ethidium bromide. Agarose gel electrophoresis of wild types and transconjugants indicated that these resistances were mediated by a 150-kilobase plasmid, pCFF14. The strains constitutively produced a beta-lactamase with isoelectric point close to 5.6 and which had a higher Vmax for ceftazidime and cephalothin than for cefotaxime. The substrate profile and isoelectric point of this enzyme thus differ from those of other known plasmid-mediated beta-lactamases, including the broad-spectrum enzyme CTX-1. Hybridization studies support the derivation of the novel enzyme from a TEM-type beta-lactamase.