Abstract：
Extensively drug-resistant (XDR) bacteria are the main caues for causing clinical infectious diseases. Our aim was to distinguish the present molecular epidemiological situation of XDR Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli isolates recovered from local hospitals in Changzhou. Antibiotic susceptibility and phenotypic analysis, multilocus sequence typing and Pulsed Field Gel Electrophoresis were performed to trace these isolates. Resistant phenotype and gene analysis from 29 XDR strains demonstrated that they mainly included TEM, CTX-M-1/2, OXA-48, and KPC products. A. baumannii strains belonged to sequence type (ST) ST224, and carrying the blaCTX-M-2/TEM gene. The quinolone genes aac(6\')-ib-cr and qnrB were carrying only in A. baumannii and E.coli. Three (2.3%) of these strains were found to contain the blaNDM-1 or blaNDM-5 gene. A new genotype of K. pneumoniae was found as ST2639. Epidemic characteristics of the XDR clones showed that antibiotic resistance genes distributed unevenly in different wards in Changzhou\'s local hospitals. With the sequencing of blaNDM carrying isolates, the plasmids often carrying a highly conservative Tn3-relavent mobile genetic element. The especially coupled insert sequence ISKox3 may be a distinctive resistance gene transfer loci. The genotypic diversity variation of XDRs suggested that tracking and isolating the sources of antibiotic resistance especially MBL-encoding genes such as blaNDM-will help manage the risk of infection by these XDRs.
摘要：
广泛耐药（XDR）细菌是引起临床感染性疾病的主要原因。我们的目的是区分肺炎克雷伯菌XDR的分子流行病学现状，鲍曼不动杆菌,和从常州当地医院回收的大肠杆菌分离株。抗生素敏感性和表型分析，进行多位点序列分型和脉冲场凝胶电泳以追踪这些分离株。29株XDR菌株的耐药表型和基因分析表明，它们主要包括TEM，CTX-M-1/2、OXA-48和KPC产品。鲍曼不动杆菌属序列型(ST)ST224,携带blaCTX-M-2/TEM基因。喹诺酮基因aac(6')-ib-cr和qnrB仅在鲍曼不动杆菌和大肠杆菌中携带。发现这些菌株中的三个(2.3%)含有blaNDM-1或blaNDM-5基因。发现肺炎克雷伯氏菌的新基因型为ST2639。XDR克隆的流行特征表明，常州当地医院不同病房的抗生素抗性基因分布不均。随着blaNDM携带分离株的测序，质粒通常携带高度保守的Tn3相关的可移动遗传元件。特别偶联的插入序列ISKox3可能是独特的抗性基因转移基因座。XDR的基因型多样性变异表明，跟踪和分离抗生素抗性的来源，尤其是MBL编码基因，如blaNDM，将有助于控制这些XDR感染的风险。
