外科监护室耐药大肠杆菌和肺炎克雷伯杆菌产超广谱β-内酰胺酶的基因型研究

Genotype of extended-spectrum β-lactamases produced by antibiotic-resistant Escherichia coli and Klebsiella pneumoniae in surgical intensive care unit

目的：了解外科监护室产生超广谱β-内酰胺酶(extended-spectram β-lactamases，ESBLs)的大肠杆菌和肺炎克雷伯杆菌的耐药性和基因型。方法：琼脂稀释法测定临床分离株的最小抑菌浓度(minimal inhibitory concentra-tion，MIC)值，分别用 TEM、SHV 和 CTX-M 的特异性引物扩增临床菌株和接合子的超广谱β-内酰胺酶基因。接合试验提取接合子质粒进行聚合酶链反应(polymerase chain reaction，PCR)，产物测序，确定基因类型。结果：93.5%的菌株含 CTX-M 基因，38.7%的菌株含 SHV 基因，87.1%的菌株含 TEM 基因。测序明确了 TEM-1，CTX-M-1，3，14，22等基因类型。结论：外科监护室大肠杆菌和肺炎克雷伯杆菌产超广谱β-内酰胺酶的基因以 CTX-M 为主。

Objective:To describe the antibiotic resistant mode of extended-spectrum β-lactamases(ESBLs)producing Escherichia coli(E coli)and Klebsiella pneumoniae(KPn)in surgical intensive careunit(SICU),and to implore the molecular epidemiology of ESBLs coding genes of these strains.Meth-ods:The minimal inhibitory concentrations(MICs)atantibiotics were examined by agar dilution method.The ESBLs coding genes were amplified by TEM,SHV and CTX-M specific primers.Amplicons of suchgenes with conjugates' plasmids as templates were sequenced.Results:In vitro susceptibility tests ofESBLs producing strains showed a high level of resistance to most of the β-lactam biotics,especially cefo-taxime.93.5% of these ESBLs positive strains contained CTX-M group genes,and 38.7% of the strainscontained SHV genes.By sequencing,some genotype were determined:TEM-1,CTX-M-1,3,14,22.Conclusion:ESBLs producing strains were resistant to most of the β-lactam biotics.The most prevalentESBLs genotype of ESBLs produced by E coli and KPn in SICU was CTX-M subgroup.The most probablereason might be the extensive use of cefotaxime.