产ESBL肺炎克雷伯菌医院感染分子流行病学研究

A molecular epidemiologic study on nosocomial infection caused by ESBL producing Klebsiella pneumoniae

目的 明确产 ESBL 肺炎克雷伯菌医院感染发生率及其流行病学特征。方法 收集、鉴定分离菌株 ,进行药敏实验和 ESBL 检测 ;PCR扩增 bla TEM和 bla SHV基因 ;等电聚焦测定 β-内酰胺酶的等电点 ( p I)、染色体 DNA的PFGE分型以及进行病例资料分析。结果 共分离到 10 4株非重复肺炎克雷伯菌 ,产 ESBL 株占 13 .5 %。医院感染株 ESBL 阳性率 ( 2 8.3 % )明显高于院外感染株 ( 3 .6% ) ;ESBL 阳性菌对 CPD、CTX、CAZ、CTR、ATM、FOX、CIP和 GEN的中敏或耐药率分别为 92 .9%、92 .9%、3 5 .7%、92 .8%、78.6%、7.1%、2 8.6%和 4 2 .9% ,但对IMP10 0 %敏感 ;β-内酰胺酶等电聚焦分析及 bla TEM和 bla SHV基因检测结果 ,提示该院流行的 ESBL 主要为 SHV类 ;PFGE分析证实在干部 1病区、SICU和 RICU存在产 ESBL 菌株流行。结论 该医院存在产 ESBL 肺炎克雷伯菌医院感染流行 ;合理使用抗生素 ,加强消毒隔离措施 ,严格遵守无菌操作规程和屏障护理 ,是控制医院感染流行的重要措施。

OBJECTIVE The purpose of this study was to determine the prevalence and mechanisms of nosocomial infections caused by ESBL producing Klebsiella pneumoniae.METHODS Isolates were collected and identified as well as subjected to drug susceptibility test,ESBL detection,β lactamase gene analysis by PCR,β lactamases study by isoelectric focusing and chromosomal DNA analysis by PFGE.RESULTS Total of 14 isolates(13.5%)of 104 nonrepetitive strains were ESBL positive by E test ESBL screen.The ESBLproducing strains were observed more frequently in nosocomail isolates(28.3%) than in community ones (3.6%).Resistant rates of ESBL producers to CPD,CTX,CAZ,CTR,ATM,FOX,CIP and GEN were 92.9%,92.9%,35.7%,92.9%,78.6%,7.1%,28.6% and 42.9% respectively,but none of them was resistant to imipenam.The results of isoelectric focusing analysis of β lactamases and PCR analysis of total bacteria DNA using bla TEM and bla SHV specific primers indicated that the predominant extended spectrum β lactamase in our hospital was SHV type β lactamase.Chromosomal DNA analysis by PFGE showed that some types of ESBL producing K.pneumoniae were epidemic in RICU,SICU and the first section of the Geriatric wards.CONCLUSIONS Nosocomial infection outbreaks caused by ESBL producing K.pneumoniae have occurred in our hospital.Barrier precaution and producuse of antibiotics are important infection control measures.