住院患者产CTX-M型ESBLs和KPC的大肠埃希菌感染分布与耐药基因分析

Distribution and antimicrobial resistance genes of CTX-M extended-spectrum β-lactamase- and Klebsiella pneumoniae carbapenemasesproducing Escherichia coli isolated from patients with infection

摘要:

目的了解住院患者产CTXM型超广谱β内酰胺酶（ESBLs）和碳青霉烯酶（KPC）大肠埃希菌感染的临床分布与耐药情况。方法收集某院2011—2012年临床送检标本分离的多重耐药大肠埃希菌，采用微量肉汤稀释法检测抗菌药物最低抑菌浓度（MIC）；聚合酶链反应（PCR）扩增ESBLs和KPC基因，确定CTXM和KPC基因型别及MLST分型。结果48株多重耐药大肠埃希菌中单产ESBLs 45株（93.75%），携带blaCTXM基因者44株（91.67%），其中blaCTXM1组基因20株（41.67%）、blaCTXM9组基因32株（66.67%），同时携带两组基因者8株（16.67%）。经基因测序确定的基因亚型有CTXM14（65.91%，29/44）、CTXM55（31.82%，14/44）、CTXM15（11.36%，5/44）、CTXM3（2.27%，1/44）、CTXM24（2.27%，1/44）和CTXM65（2.27%，1/44），其中CTXM14+CTXM55（11.36%，5/44）、CTXM14+CTXM15（4.55%，2/44）和CTXM55+CTXM65（2.27%，1/44）。产ESBLs+KPC菌株中2株（4.17%）经PCR扩增均携带blaKPC和 blaCTXM基因，经测序分析1株为CTXM14+KPC2，1株为CTXM3+KPC2。ST131 （53.66%）是主要的MLST型别，检测到ST648、ST405、ST167、ST1193等ST型。 结论该院大肠埃希菌产ESBLs基因型中CTXM14、CTXM55和CTXM15亚型最常见，存在多种不同亚型；ST131是主要的MLST型别，检测到产KPC2型碳青霉烯酶菌。

Abstract:

ObjectiveTo investigate clinical distribution and antimicrobial resistance genes of  CTXM extendedspectrum βlactamases (ESBLs) and Klebsiella pneumoniae carbapenemases (KPCs)producing Escherichia coli (E. coli) isolated from patients with infection. MethodsMultidrugresistant E. coli (MDRE. coli) isolated from clinical specimens in a hospital in 2011-2012 were collected, minimal inhibitory concentrations (MICs) were detected by microbroth dilution method; ESBLs and KPC genes were amplified by polymerase chain reaction (PCR),  CTXM and KPC genotypes，as well as multilocus sequence types (MLST) were identified. ResultsOf 48 MDRE.coli, 45（93.75%） only produced ESBLs, 44（91.67%） carried  blaCTXM gene, 20（41.67%） of which were blaCTXM1 gene and 32（66.67%）were blaCTXM9 gene，8（16.67%）carried both genes. The following subtypes were identified through gene sequencing: CTXM14（65.91%，29/44）, CTXM55（31.82%，14/44）, CTXM15（11.36%，5/44）, CTXM3（2.27%，1/44）, CTXM24（2.27%，1/44）,and CTXM65（2.27%，1/44）. The detection rates of CTXM14+CTXM55, CTXM14+CTXM15, and CTXM55+CTXM65 were 11.36% (5/44）, 4.55%(2/44）, and 2.27%(1/44）respectively. PCR showed that 2(4.17%） ESBLs+KPCproducing strains carried blaKPC and  blaCTXM genes, sequencing analysis showed that 1 was CTXM14+KPC2，and the other was CTXM3+KPC2. ST 131 （53.66%）was the main type of MLST,  ST648, ST405, ST167, and ST1193 were also detected. ConclusionCTXM14, CTXM55 and CTXM15 are the most common genotypes of ESBLsproducing E. coli isolates, different subtypes exists, ST131 is the predominant MLST, KPC2producing  isolate of E.coli has been detected.