摘要
目的 调查我院院内肠杆菌科细菌中产超广谱 β 内酰胺酶 (ESBL)菌株的发生率以及ESBL的表型和基因型。方法 对 1999年 2月～ 5月临床分离的 16 2株肠杆菌科细菌 ,采用美国临床实验室标准化委员会规定的ESBL表型筛选和确证试验确定ESBL的发生率 ;等电聚焦电泳、抑制试验、接合试验确定ESBL菌株中酶的表型 ;质粒的提取、脉冲场凝胶电泳 (PFGE)、TEM 、SHV 、CTX M 3特异引物的PCR和测序确定ESBL的基因型。结果 11.4% (5 44 )的大肠杆菌、39.5 % (17 43)的肺炎克雷伯菌、6 .0 % (3 5 0 )的阴沟肠杆菌和 8.0 % (2 2 5 )的弗劳地枸橼酸菌产ESBL。对于这 2 7株菌 ,头孢噻肟的MIC明显高于头孢他啶。除 1株阴沟肠杆菌外 ,其它 2 6株菌对亚胺培南敏感。大多数菌株产2～ 6种酶。 70 .3% (19 2 7)的菌株产生CTX M 3型的ESBL (等电点为 8.6 ) ,这种酶能被克拉维酸抑制 ,其编码的耐药性能够转移至敏感株 ,并且对头孢噻肟的耐药高于头孢他啶。对小部分菌株用PF GE分型发现存在多个克隆。结论 产ESBL的肠杆菌科在院内较普遍 ;CTX M 3型的ESBL最为常见。
Objective To investigate the prevalence, phenotypical and genotypical characteristics of extended spectrum β lactamases producing Enterobacteriaceae strains from Peking Union Medical College Hospital in China. Methods 162 strains of nosocomial Enterobacteriaceae from February to April, 1999 were investigated for the production for extended spectrum β lactamases (ESBLs) by phenotypic screening and confirmatory test provided by the National Committee for Clinical Laboratory Standards. Isoelectric focusing, inhibition assay, conjugation were used to determine the phenotype of the enzyme; Plasmid DNA preparation, pulsed field gel electrophoresis (PFGE), TEM or SHV or CTX M3 specific PCR and DNA sequencing were used to determine the genotype of the enzymes. Results 11.4% (5/44) of E.coli , 39.5% (17/43) of K.pneumoniae , 6.0% (3/50) of E.cloacae and 8.0% (2/25) of C.freundii produced ESBLs. Cefotaxime MICs was much higher than ceftazidime in the ESBL producing strains, and all of the strains were susceptible to imipenem except 1 strain of E.cloacae . Most isolates produced two to six enzymes. 19 of 27 ESBL producing strains (70.3%) expressed CTX M 3 β lactamase (pI 8.6), which can be inhibited by clavulanate. This ESBL properties can be transferred into E.coli C600 and conferred higher resistance to cefotaxime than ceftazidime. A subset of clinical isolates tested by PFGE of chromosomal DNA revealed multiple clones. Conclusion ESBL producing strains were very common in this hospital and CTX M 3 β lactamase was the most prevalent. [
出处
《中华微生物学和免疫学杂志》
CAS
CSCD
北大核心
2001年第6期676-679,共4页
Chinese Journal of Microbiology and Immunology
