ICU病区大肠埃希菌中qnr基因的分布与耐药性的研究

目的调查温州医科大学附属第一医院ICU病区分离的大肠埃希菌基因的分布以及与耐药谱的关系，并初步探讨其在分子流行病学中的作用。方法收集2012年1-9月ICU病区分离的大肠埃希菌76株进行qnr基因检测，并通过DNA直接测序确定;分析qnr基因在ICU病区分离的大肠埃希菌的分布及其与耐药性的关系。结果根据PCR产物片段大小及测序分析，76株大肠埃希菌中共有qm基因阳性菌株46株，阳性率为60. 5% ;对阳性菌株进行DNA测序、BLAST比对,其中25株为qnrB基因，17株为qnrS基因阳性，12株基因阳性，未检测到qwC和qnrD基因。在46株qnr基因阳性菌株中有38株为产ESBL菌株,而在qnr阴性菌株中仅有5株ESBL阳性。结论该院ICU分离大肠埃希菌qnr基因携带严重，呈现出多重耐药性，多伴随呈现为产ESBL菌株。

The prevalence of qnr gene and drug resistance in Escherichia coli

Objective To investigate the prevalence of qnr gene and to analyze their effect on the drug resistance in multi drug-resistant strains of Escherichia coli. Methods A total of 76 isolates of Escherichia coli were isolated from clinical specimens in our hospitalfrom Jan to sep 2012. qnr genes was determined by PCR. All PCR products were sequenced for determination. Analysis the distributionand relationship between the two resistance genes in the Enterobacter cloacae. Results qnr genes was present in 46 （60. 5% ） of the 76isolates. The positive isolates were sequenced, 25 isolates harbored qnrB,17 isolates contained qnr S. While only 12 strains were positiveof qnrA gene. The qnrC and qnrD genes were not detected. Among the 46 qnr positive isolates, there were 38 ESBL-producing strains.However, there were only 5 ESBL strains in 30 qnr negative isolates. Conclusion The resistance of Escherichia coli isolated in ICUwards of our hospital is serious. The fluoroquinolone resistance is mainly mediated the qnr genes,commonly accompanied by ESBLstrains.