CTX-M-3超广谱-和TEM-1广谱β-内酰胺酶基因同时存在于大肠埃希菌

Finding of CTX-M-3 extended-spectrum β-lactamase coexistent with TEM-1 broad-spectrum-β-lactamase in clinical isolates of Escherichia coli

目的 分析我院大肠埃希菌临床分离株中超广谱 β 内酰胺酶 (ESBLs)的基因型。方法用NCCLS表型确证试验确定临床标本中产ESBLs的大肠埃希菌 ,用Etest检测其MIC值 ,分别用TEM、SHV和CTX M通用引物进行PCR扩增并对PCR产物进行序列分析。结果 我院大部分产ESBLs的大肠埃希菌体外对头孢噻肟耐药而对头孢他啶敏感。这些菌株以TEM和CTX M引物的PCR扩增结果均出现阳性条带 ,而SHV引物的PCR均无条带产生 ,测序发现阳性条带分别为TEM 1和CTX M 3基因序列。结论 发现CTX M 3型ESBL和TEM 1广谱 β

Objective To find the genotypical characteristics of extended-spectrum-β-lactamase(ESBLs) in clinical isolates of Escherichia coli. Methods The clinical isolates of ESBLs producing E.coli were confirmed by the NCCLS phenotypic confirmatory test, and the MICs were determined by Etest. PCR were performed using primers specific for blaTEM, blaSHV and blaCTX-M respectively, and the PCR products were purified and directly sequenced by ABI PRISM377 DNA sequencer. Results The phenotype of most ESBLs producing E.coli was resistance to cefotaxime and susceptible to ceftazidime. PCR experiment gave blaTEM -positive, blaCTX-M-positive and blaSHV-negative results for all the strains detected, and it was confirmed as TEM-1 and CTX-M-3 respectively. Conclusion CTX-M-3 was found in the mainland of China, and CTX-M-3 coexistent with TEM-1 is the prevalent genotype of extended-spectrum β-lactamase in clinical isolates of Escherichia coli in our hospital.