一种新型β-内酰胺酶OKP-B-13的发现

A Novel Beta-lactamase in ESBLs-producing Klebsiella pneumoniae

目的鉴定一种新型超广谱β-内酰胺酶肺炎克雷伯菌的基因亚型并分析其耐药性。方法分析11种抗菌药物对该菌株的最低抑菌浓度（MIC）,并以碱裂解法抽提菌株的质粒DNA,应用聚合酶链反应（PCR）扩增产ESBLs株质粒的TEM、SHV、CTX基因,对其扩增产物进行DNA序列分析。结果TEM基因和CTX-M基因的PCR扩增结果均显示为阴性,SHV基因的PCR扩增获得862 bp产物;DNA测序未能在GenBank数据库查询到与之相一致的核苷酸序列,该基因编码的氨基酸序列与OKP型β-内酰胺酶为最相近,存在4-18个氨基酸差异,与SHV-1同源性为90%;此新型β-内胺酶被命名为OKP-B-13（GenBank注册号AY825330）。结论发现了一种新型的产ESBLs肺炎克雷伯菌β-内酰胺酶-OKP-B-13,其酶特性有待进一步研究。

OBJECTIVE To identify a novel genotype of the β-lactamases produced in ESBLs-producing Klebsiella pneumoniae.METHODS Minimal inhibitory concentrations（MIC） for 11 antibiotics against the isolate were determined.Plasmid DNA was extracted by the alkaline lysis method.Nucleotide sequences of TEM,SHV and CTXM genes in the ESBL-producing isolate were amplified by PCR.The purified PCR products were sequenced.RESULTS TEM and CTX-M genes were not detected in this isolate.A 862 bp nucleotide product was amplified by the SHV gene primers.The analysis of DNA sequence showed that it was a novel β-lactamase gene.The amino acid sequence of novel β-lactamase gene was most similar to OKP type β-lactamase and there was 4 to 18 amino acid difference between them.But it shared only 90% identity with SHV-1.It was named as OKP-B-13 β-lactamase（GenBank No.AY825330）.CONCLUSIONS OKP-B-13 is a novel β-lactamase found in a K.pneumoniae strein.