临床分离的大肠杆菌和肺炎克雷伯菌中产超广谱β-内酰胺酶的分子特征

Molecular characterization of extended spectrum beta-lactamase among clinical isolates Escherichia coli and Klebsiella pneumoniae.

作者信息

Udomsantisuk Nibondh, Nunthapisud Pongpun, Tirawatanapong Thaweesak, Dansuputra Mayteera

机构信息

Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

出版信息

J Med Assoc Thai. 2011 Dec;94(12):1504-12.

PMID:22295740

Abstract

BACKGROUND

Resistance to beta-lactams has been increasing in the treatment of infections caused by Escherichia coli and Klebsiella pneumoniae. The production of extended-spectrum beta-lactamases (ESBLs), that hydrolyze extended-spectrum cephalosporins, is the major cause of beta-lactam resistance.

OBJECTIVE

To determine the prevalence and characterize of ESBLs produced by E. coli and K. pneumoniae from clinical specimens.

MATERIAL AND METHOD

ESBLs were determined by disk diffusion test, double disk synergy test, and E-test ESBLs. All ESBLs producing isolates were investigated for the presence of bla(TEM) bla(SHV), bla(CTX-M) and bla(VEB) genes by polymerase chain reaction (PCR). Nucleotide sequencing of bla(TEM) and bla(SHV) were performed E. coli and K. pneumoniae were isolated from clinical specimens of patients in King Chulalongkorn Memorial Hospital between February and May 2002. Of the 270 isolates, 212 were E. coli and 58 were K. pneumoniae.

RESULTS

ESBL roduction was detected in 17% (36/212) of E. coli and 34.5% (20/58) of K. pneumoniae isolates. Of the 20 K. pneumoniae isolates, the beta-lactamase genes were bla(SHV) (18/20, 90%), bla(TEM) (10/20, 50%), bla(VEB-like) (6/20, 30%) and bla(CTX-M-like) (3/20, 15%). Thirty-six E. coli isolates carried bla(TEM) bla(CTX-M-like) and bla(VEB-like) genes in 72.2% (26/36), 52.8% (19/36) and 16.7% (6/36), respectively Bla(SHV) was not detected in ESBL-producing E. coli, whereas it predominated in K. pneumoniae. Of the 56 ESBL producing isolates, 30 (53.6%) coharboured at least two different bla genes. All TEM identified were TEM-1B, which is not an ESBL. CTX-M ESBLs were the most common in E. coli.

CONCLUSION

The double disk diffusion test should be added routinely in the antibiotic susceptibility test for the Enterobacteriaceae. It is simple to perform, easy to interpret, and economical. The presence of bla(CTX-M) and bla(VEB) in ESBL-producing E. coli and K. pneumoniae indicates the high prevalence of these genes in Thailand.

摘要

背景

在大肠杆菌和肺炎克雷伯菌引起的感染治疗中，对β-内酰胺类药物的耐药性一直在增加。超广谱β-内酰胺酶（ESBLs）的产生可水解超广谱头孢菌素，是β-内酰胺类耐药的主要原因。

目的

确定临床标本中大肠杆菌和肺炎克雷伯菌产生的ESBLs的流行情况并进行特征分析。

材料与方法

采用纸片扩散法、双纸片协同试验和E-test法检测ESBLs。通过聚合酶链反应（PCR）对所有产ESBLs菌株进行bla(TEM)、bla(SHV)、bla(CTX-M)和bla(VEB)基因检测。对bla(TEM)和bla(SHV)进行核苷酸测序。2002年2月至5月从朱拉隆功国王纪念医院患者的临床标本中分离出大肠杆菌和肺炎克雷伯菌。在270株分离菌株中，212株为大肠杆菌，58株为肺炎克雷伯菌。

结果

在212株大肠杆菌分离株中，17%（36/212）检测到产ESBLs；在58株肺炎克雷伯菌分离株中，34.5%（20/58）检测到产ESBLs。在20株肺炎克雷伯菌分离株中，β-内酰胺酶基因bla(SHV)占90%（18/20），bla(TEM)占50%（10/20），bla(VEB样)占30%（6/20），bla(CTX-M样)占15%（3/20）。36株大肠杆菌分离株中，分别有72.2%（26/36）、52.8%（19/36）和16.7%（6/36）携带bla(TEM)、bla(CTX-M样)和bla(VEB样)基因。产ESBLs的大肠杆菌中未检测到bla(SHV)，而在肺炎克雷伯菌中占主导地位。在56株产ESBLs菌株中，30株（53.6%）至少携带两种不同的bla基因。所有鉴定出的TEM均为TEM-1B，它不是ESBL。CTX-M型ESBLs在大肠杆菌中最常见。