肺炎克雷伯菌超广谱β内酰胺酶及AmpC酶分析研究

Detection of extended-spectrum and AmpC β-lactamases among Klebsiella pneumoniae isolates

目的 :研究目前我国肺炎克雷伯菌中超广谱 β内酰胺酶 (ESBLs)及质粒介导AmpC酶产生情况。 方法 :以美国国家临床实验室标准委员会 (NCCLS)推荐纸片扩散法确证试验检测肺炎克雷伯菌产ESBLs情况 ,以三维试验检测其产质粒介导AmpC酶情况。等电聚焦电泳测定所产粗酶的等电点。聚合酶链反应 (PCR)检测 β内酰胺酶亚型。DNA序列测定判断质粒介导AmpC酶的种类。结果 :检出产ESBLs肺炎克雷伯菌 37株 ,检出率 17.5 % (37/ 2 12 )。三维试验检测出产质粒介导AmpC酶肺炎克雷伯菌 2株 ,检出率 0 .9% (2 / 2 12 ) ,此 2株菌均同时产ESBLs。在所产ESBLs中 ,CTX M型占 83.8% (31/ 37) ,其中CTX M 1组占 5 4 .1% (2 0 / 37) ,Toho 2组占 2 9.7% (11/ 37) ,CTX M 1组∶Toho 2组为 1.8∶1;SHV型占 2 4 .3% (9/ 37)。DNA测序结果 ,1株肺炎克雷伯菌所产质粒介导AmpC酶为DHA 1。结论 :①肺炎克雷伯菌中ESBLs以CTX M型为主。②在肺炎克雷伯菌中发现 1株质粒介导AmpC酶为DHA 1。

Objective: To investigate the prevalence of extended-spectrum β-lactamases (ESBLs) and AmpC lactamases in cli-nical isolates of Klebsiella pneumoniae in China. Methods:ESBLs were detected by screening and confirmatory methods recommended by NCCLS. AmpC β-lactamases were detected by three-dimensional extract test. Isoelectric focusing analysis and PCR were performed to determine the sub-types of ESBLs and AmpC β-lactamases. Results:Of 212 strains tested, ESBLs were detected in 37 (17.5%) strains and AmpC-type β-lactamases in 2 (0.94%) strains of K. pneumoniae (these 2 strains produced ESBLs simultaneously). Among 37 ESBL-producing strains, 31 (83.8%) produced CTX-M type β-lactamases in which 20 (54.1%) and 11 (29.7%) belonged to CTX-M-1 and Toho-2 respectively, 9 (24.3%) strains produced SHV type ESBLs (both CTX-M and SHV were detected in 3 strains simultaneously). DNA sequencing results demonstrated that one strain of produced DHA-1 AmpC-type β-lactamase. Conclusions:CTX-M type ESBLs are the most common ESBLs in K. pneumoniae in China. DHA-1 AmpC-type plasmid-mediated β-lactamase can be found in K. pneumoniae.