广州地区3500株革兰阴性杆菌TEM和SHV型超广谱β内酰胺酶基因分型研究  

Study on the genotypes of TEM-like and SHV-like extended-spectrum beta-lactamases in clinical isolates of Gram-negative bacilli in Guangzhou

作　　者：肖庆忠[1] 苏丹虹[1] 江洁华[1] 钟南山[2] 

机构地区：[1]广州医学院第一附属医院检验科,510120 [2]广州市呼吸疾病研究所

出　　处：《中华检验医学杂志》2005年第10期1010-1014,共5页Chinese Journal of Laboratory Medicine

基　　金：广州市科技局重大攻关项目资助(2000-Z-027-01-2)

摘　　要：目的调查广州地区临床分离的革兰阴性杆菌中TEM和SHV型超广谱β内酰胺酶(ESBLs)的主要基因型别及其流行情况。方法按照美国临床实验室标准化委员会2001年标准筛选广州地区临床分离菌株的ESBLs表型。用聚合酶链反应(PCR)扩增法和DNA测序法进行ESBLs基因序列分析。结果2001年7月—2003年8月本研究小组从广州地区13家大型医院中共获得3500株无重复地连续地革兰阴性杆菌分离菌株,其中ESBLs表型阳性为1084株,占31%。PCR扩增结果显示,blaTEM和blaSHV基因的总阳性率在本地区临床分离的革兰阴性杆菌中分别为24%和10·8%,同时检出TEM和SHV型ESBLs的菌株数为128株,阳性率为3·7%。序列分析进一步证实了TEM型bla均为TEM-1类非ESBLs,包括TEM-1、TEM-1B、TEM-1D和TEM-1F。而本地区的SHV型bla几乎均为SHV类ESBLs(SHV-1型仅占7·2%,获得22株),其中以SHV-12/5a阳性率最高(50%,152/304)。各基因型的菌株分布结果显示,TEM型基因主要分布于大肠埃希菌中,占53%(340/641);而SHV型基因则主要分布于肺炎克雷伯菌中,占57·9%(176/304)。结论本地区SHV类ESBLs较为常见,其中尤以SHV-12/5a为主,本地区暂无TEM类ESBLs。本地区可能存在SHV-12/5a流行菌株。对于ESBLs的检测,临床常用方法可能存在较高的漏检率和误检率。Objective To investigate the main genotypes and the epidemic characteristics of TEMtype and SHV-type extended-spectrum beta-lactamases （ESBLs） of the gram-negative bacilli in Guangzhou. Methods The phenotype of ESBLs from 3 500 clinical isolates were primary screened and confirmed by the NCCLS confirmatory test according to guidelines of NCCLS（2001 ）. PCR were performed on 3 500 clinical isolates using primers specific for blaTEM and blaSHV, respectively, the PCR product were purified and sequenced by ABI prism 377 DNA sequencer. Results Total of 3 500 un-replicated and consecutive Gram-negative bacilli were isolated from 13 hospitals in Guangzhou in the past two years, and the prevalence of ESBLs-producing clinical Gram-negative isolates was 31.0% （ 1 084/3 500）. The positive rates of PCR results for blaTEM, blaSHV, and both of them in all the clinical Gram-negative isolates were 24. 0% （840/3 500）, 10. 8% （378/3 500） ,and 3.7% （ 128/3 500）, respectively. All PCR products for blaTEM were further identified as TEM-l-type non-ESBLs gene, including TEM-1, TEM-1B, TEM-1D, and TEM-1F,by DNA sequencing analyses. However, almost all of the blaSHV gene were further identified as SHV-type ESBLs gene（ the prevalence of SHY-1 is 7. 2% only）. The prevalence of SHV-12/Sa accounted for highest（50. 0% ,152/304） in Guangzhou. Our test also showed that 53% （340/641） of blaTEM-producers were Escherichia coli, and 57. 9% （176/304） of blaSHV-producers were Klebsiella pneumoniae. Conclusions We could conclude from above results that SHV-type ESBLs, especial SHV-12/Sa, was the prevalent genotype of ESBLs of clinical gram-negative bacilli in Guangzhou. TEM-type ESBLs did not exist in our city. In addition, SHV-12/Sa-producing strains probably were main epidemic strains in Guangzhou. As for detection of ESBLs with regular phenotype methods, there was possibility of false negative and false positive.

关 键 词：革兰阴性菌感染 Β内酰胺酶类 基因型 

分 类 号：R446.5[医药卫生—诊断学]