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

摘要

Objective To investigate clinical distribution and antimicrobial resistance genes of CTX-M extended-spectrumβ-lactamases (ESBLs)- and Klebsiella pneumoniae carbapenemases (KPCs)-producing Escherichia coli (E.coli)isolated from patients with infection.Methods Multidrug-resistant E.coli (MDR-E.coli)isolated from clinical specimens in a hospital in 2011 -2012 were collected,minimal inhibitory concentrations (MICs)were detec-ted 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.Results Of 48 MDR-E. coli,45(93.75%)only produced ESBLs,44(91 .67%)carried bla CTX-M gene,20(41 .67%)of which were bla CTX-M-1 gene and 32(66.67%)were bla CTX-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 bla KPC and bla CTX-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. Conclusion CTX-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.%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 bla CTX-M 基因者44株（91．67％），其中 bla CTX-M-1组基因20株（41．67％）、bla CTX-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 bla KPC 和 bla CTX-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。