Ding H, Yang Y, Lu Q, Wang Y, Chen Y, Deng L, Wang A, Deng Q, Zhang H, Wang C, Liu L, Xu X, Wang L, Shen X
Beijing Children's Hospital, Affiliated to Capital Medical University, 56 South Lishi Road, Beijing, 100045, People's Republic of China.
Eur J Clin Microbiol Infect Dis. 2008 Oct;27(10):915-21. doi: 10.1007/s10096-008-0532-4. Epub 2008 May 1.
The purpose of this study was to investigate the prevalence of plasmid-mediated AmpC beta-lactamases in Escherichia coli and Klebsiella pneumoniae from five children's hospitals in China. A total of 494 E. coli and 637 K. pneumoniae isolates were collected from five children's hospitals in China from 2005 to 2006. The isolates with decreased susceptibility to cefoxitin were subjected to confirmation test with 3-aminophenyl boronic acid. Polymerase chain reaction (PCR) amplification of the blaAmpC, blaTEM, blaCTXM, and blaSHV genes and their gene sequencing were performed. Transconjugants were achieved by conjugation experiments. Plasmid-mediated AmpC beta-lactamases were found in 10.1% of K. pneumoniae (64/637) and in 2.0% of E. coli (10/494) strains. The proportion of plasmid-mediated AmpC-producing strains significantly increased from 2005 (2.6%) to 2006 (9.3%) (p<0.001). The DHA-1-producing isolates were the most prevalent type (93.2%, 69/74). The sequences of blaDHA-1 genes were all identical to those from the GenBank. Strains of blaCMY-2 were isolated from five isolates (6.8%), which were all from E. coli. One sequence of blaCMY-2 differs from blaCMY-2 in the GenBank. Eighteen of the 74 (24.3%) AmpC-producing K. pneumoniae and E. coli isolates coproduced an extended-spectrum beta-lactamase (ESBL). Cefoxitin resistance was transferred to 15 of the 74 positive strains (20.3%). Our study has demonstrated the occurrence of plasmid-mediated AmpC beta-lactamases in E. coli and K. pneumoniae in Chinese pediatric patients and DHA-1 type AmpC enzymes had the highest prevalent rate. The CMY-2 AmpC beta-lactamases from the children's hospitals in China in this study are the first reported. Hence, continuous surveillance of the prevalence and evolution of AmpC beta-lactamase is important.
本研究旨在调查中国五家儿童医院分离的大肠埃希菌和肺炎克雷伯菌中质粒介导的AmpCβ-内酰胺酶的流行情况。2005年至2006年，从中国五家儿童医院共收集了494株大肠埃希菌和637株肺炎克雷伯菌。对头孢西丁敏感性降低的菌株用3-氨基苯硼酸进行确证试验。进行blaAmpC、blaTEM、blaCTXM和blaSHV基因的聚合酶链反应（PCR）扩增及其基因测序。通过接合实验获得接合子。在10.1%的肺炎克雷伯菌（64/637）和2.0%的大肠埃希菌（10/494）菌株中发现了质粒介导的AmpCβ-内酰胺酶。质粒介导的产AmpC菌株比例从2005年的2.6%显著增加到2006年的9.3%（p<0.001）。产DHA-1的分离株是最常见的类型（93.2%，69/74）。blaDHA-1基因序列与GenBank中的序列完全相同。从五株分离株（6.8%）中分离出blaCMY-2菌株，均来自大肠埃希菌。blaCMY-2的一个序列与GenBank中的blaCMY-2不同。74株产AmpC的肺炎克雷伯菌和大肠埃希菌分离株中有18株（24.3%）同时产生超广谱β-内酰胺酶（ESBL）。74株阳性菌株中有15株（20.3%）的头孢西丁耐药性得以转移。我们的研究表明中国儿科患者的大肠埃希菌和肺炎克雷伯菌中存在质粒介导的AmpCβ-内酰胺酶，且DHA-1型AmpC酶的流行率最高。本研究中来自中国儿童医院的CMY-2 AmpCβ-内酰胺酶为首次报道。因此，持续监测AmpCβ-内酰胺酶的流行情况和演变很重要。
