产超广谱β-内酰胺酶革兰阴性杆菌临床分离株的分布与基因型研究

Distribution and Genotyping of Extended-spectrum Beta-lactamases in Gram-negative Rods

目的了解临床分离的革兰阴性杆菌中产ESBLs的分布、耐药性及ESBLs基因型。方法对医院临床分离的革兰阴性杆菌,采用CLSI标准检测产ESBLs菌株,用PCR对ESBLs基因进行分型。结果 120株革兰阴性杆菌分离出38株产ESBLs菌,阳性率31.7%,其中,第1位是大肠埃希菌(53.8%),其次产酸克雷伯菌(35.3%)、肺炎克雷伯菌(33.3%);药敏结果显示,除对碳青酶烯类抗菌药物敏感外,ESBLs阳性株对多种抗菌药物的耐药率均较高,且明显高于ESBLs阴性株;38株产ESBLs菌基因型为TEM、SHV、CTX-M的分别为20、4、6株,有4株同时携带两种β-内酰胺酶基因的菌株,其他基因型4株。结论调查结果表明医院产ESBLs菌分离率较高,主要以大肠埃希菌、产酸克雷伯菌、肺炎克雷伯菌为主,其基因主要以TEM型、CTX-M型流行为主。

OBJECTIVE To study the distribution characteristics of extended-spectrum beta-lactamases（ESBLs） producing strains and the genotype of ESBLs.METHODS The Gram-negative rods were detected by screening and confirmatory test.The genotype of ESBLs was confirmed by PCR analysis.RESULTS From 120 Gram-negative rods 38 ESBLs producing strains（32%） were isolated,the first three isolates with the highest ESBLs producing rate were Escherichia coli（53.8%） Klebsiella oxytoca（35.3%）,and K.pneumoniae（33.3%）.PCR products revealed that 20 strains harbored TEM type,4 strains with SHV type and 6 strains with CTX-M using their specific primers.Four strains with two kinds of β-lactamase genes were found from the 38 ESBLs producing isolates.CONCLUSION E.coli,K.oxytoca and K.pneumoniae are the most common bacteria producing ESBLs.The ESBLs producing isolates mainly carry the TEM and CTX-M resistant genes.