Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P.O. Box 577, Jhang Road, Faisalabad, Pakistan, an affiliated institute of Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan.
Int J Antimicrob Agents. 2013 Jun;41(6):524-6. doi: 10.1016/j.ijantimicag.2013.02.017. Epub 2013 Apr 24.
The aim of this study was to characterise extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolated from urinary tract and wound infections from Pakistan (n=25). Isolates were subjected to commercially available microarray analysis to determine the presence of ESBLs and acquired AmpC enzymes. The genetic diversity of the isolates was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Plasmid replicon typing and capsular serotyping were conducted by PCR. Finally, screening for virulence genes, plasmid-mediated quinolone resistance (PMQR) genes, and genes encoding 16S rRNA methylases was done using PCR. All K. pneumoniae isolates hosted blaCTX-M genes and all strains belonged to phylogroup CTX-M-1. Acquired AmpC β-lactamases (ACT/MIR and CIT group) were found in 16% of isolates. Two clusters were observed with ≥80% similarity among profiles obtained by PFGE, and two sequence types (STs) by MLST, namely ST215 and ST307, were observed in these clusters. Three ST215 isolates carried virulence factor wcaG and three ST215 isolates had capsular type K20. IncFIA, IncFIB, IncFIIK and FrepB replicons were most commonly found in this collection. Among the PMQR determinants, aac(6')-lb-cr was present in 96% (24/25) of the isolates, qnrB was found in 88% (22/25) and qepA was found in 4% (1/25). The 16S rRNA methylase-encoding gene rmtB was found in 60% (15/25) of the isolates. In conclusion, CTX-M-producing ST215 and ST307 K. pneumoniae were the two major clones detected. Of particular concern was the high prevalence of 16S rRNA methylases conferring resistance to all aminoglycosides.
本研究的目的是对来自巴基斯坦的尿路感染和伤口感染患者分离的产超广谱β-内酰胺酶（ESBL）肺炎克雷伯菌（n=25）进行表型特征分析。采用商业化微阵列分析来确定 ESBL 和获得性 AmpC 酶的存在。通过脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）来确定分离株的遗传多样性。通过 PCR 进行质粒复制子分型和荚膜血清分型。最后，通过 PCR 对毒力基因、质粒介导的喹诺酮耐药（PMQR）基因和编码 16S rRNA 甲基化酶的基因进行筛选。所有肺炎克雷伯菌分离株均携带 blaCTX-M 基因，且所有菌株均属于 CTX-M-1 谱系组。在 16%的分离株中发现了获得性 AmpC 内酰胺酶（ACT/MIR 和 CIT 组）。通过 PFGE 获得的图谱和 MLST 获得的两种序列类型（ST）中观察到≥80%相似性的两个聚类，分别为 ST215 和 ST307。这两个聚类中发现了三个 ST215 分离株携带毒力因子 wcaG，三个 ST215 分离株具有荚膜型 K20。IncFIA、IncFIB、IncFIIK 和 FrepB 复制子在本研究中最为常见。在 PMQR 决定因素中，aac(6')-lb-cr 在 96%（25/25）的分离株中存在，qnrB 在 88%（25/25）的分离株中存在，qepA 在 4%（1/25）的分离株中存在。16S rRNA 甲基化酶编码基因 rmtB 在 60%（25/25）的分离株中存在。总之，检测到的两种主要克隆是产 CTX-M 的 ST215 和 ST307 肺炎克雷伯菌。特别令人关注的是，16S rRNA 甲基化酶的高流行率赋予了对所有氨基糖苷类药物的耐药性。
