Niumsup Pannika R, Tansawai Uttapoln, Boonkerd Nitsara, Polwichai Pitimon, Dejsirilert Surang
Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, 65000, Thailand.
J Infect Chemother. 2008 Dec;14(6):404-8. doi: 10.1007/s10156-008-0642-z. Epub 2008 Dec 17.
Fifty clinical isolates of Klebsiella pneumoniae and Escherichia coli with reduced susceptibility to third-generation cephalosporins, collected from 11 hospitals in Thailand, were studied. All isolates were found to produce extended-spectrum beta-lactamase (ESBL), as judged by double-disk synergy and combination disk methods. Most ESBL-producing K. pneumoniae isolates were resistant to ceftazidime (94%) and aztreonam (90%). In contrast, most ESBL-producing E. coli isolates were resistant to ceftriaxone (95%) and cefotaxime (74%). Plasmid DNA was isolated and beta-lactamase genes were identified by PCR and sequencing. We found that SHV-12 and CTX-M-14 were the main ESBLs responsible for resistance in K. pneumoniae and E. coli, respectively. SHV-27, SHV-28, and CTX-M-14 were detected in three, two, and four K. pneumoniae isolates, respectively. A high genetic diversity among ESBL-producing K. pneumoniae and E. coli isolates was observed. In addition, the finding of a few isolates that produced identical restriction patterns on pulsed field gel electrophoresis (PFGE) suggests the clonal spread of resistant bacteria within the hospital.
对从泰国11家医院收集的50株对第三代头孢菌素敏感性降低的肺炎克雷伯菌和大肠埃希菌临床分离株进行了研究。通过双纸片协同试验和组合纸片法判断，所有分离株均产超广谱β-内酰胺酶（ESBL）。大多数产ESBL的肺炎克雷伯菌分离株对头孢他啶（94%）和氨曲南（90%）耐药。相比之下，大多数产ESBL的大肠埃希菌分离株对头孢曲松（95%）和头孢噻肟（74%）耐药。分离质粒DNA，通过PCR和测序鉴定β-内酰胺酶基因。我们发现，SHV-12和CTX-M-14分别是肺炎克雷伯菌和大肠埃希菌耐药的主要ESBL。分别在3株、2株和4株肺炎克雷伯菌分离株中检测到SHV-27、SHV-28和CTX-M-14。观察到产ESBL的肺炎克雷伯菌和大肠埃希菌分离株之间存在高度的遗传多样性。此外，少数分离株在脉冲场凝胶电泳（PFGE）上产生相同的限制性图谱，这一发现表明耐药菌在医院内的克隆传播。
