产NDM-1型碳青霉烯酶摩根摩根菌的分离及分子背景研究

Isolation and molecular analysis of bIaNDM-1-pOsitive Morganella morganii

目的对发现的产新德里金属β内酰胺酶1（NDM-1）型碳青霉烯酶摩根摩根菌进行分子背景研究。方法两株碳青霉烯类抗生素耐药摩根摩根菌1和2分别于2013年10月4日和10月29日分离自浙江省嘉兴市第二医院。琼脂稀释法测定抗生素敏感性；脉冲场凝胶电泳（PFGE）分析两菌株同源性；特异性PCR扩增和序列分析、接合试验和耐药基因周围序列分析进行菌株耐药机制分子水平研究。结果2株菌对喹诺酮类和碳青霉烯类抗生素耐药，对氨曲南敏感；PFGE结果显示2株菌非同源；特异性PCR扩增和序列分析发现2株菌同时携带耐药基因blaNDM-1、blaSHV-12、qnrS1和aac（6’）-Ib-cr；接合子中同时携带blaNDM-1和qnrS1；耐药基因blaNDM-1周围序列分析发现，2株菌blaNDM-1周围序列blaNDM-1-bleMBL-trpF—dsbC-cutA1与国内已知肺炎克雷伯菌blaNDM-1基因周围序列一致。结论摩根摩根菌中blaNDM-1可能通过可转移的质粒从肺炎克雷伯菌中获得。

Objective To investigate the molecular background of the New Delhi-metallo-1 （ NDM- 1 ） -producing Morganella morganii. Methods Two carbapenem-resistant M. morganii named 1 and 2 were isolated in the Second Hospital of Jiaxing, Zhejiang on October 4th and 29th, respectively. Antimicrobial susceptibility was determined by agar dilution method. Pulsed-field gel electrophoresis （PFGE） was performed to analyse the homololgy of isolates. Amplification with specific primers, DNA sequencing, conjugation experiments and genetic environment analysis were conducted to investigate the molecular mechanisms of resistance. Results The two M. morganii isolates were resistant to carbapenem and fluoroquinolones, while susceptible to aztreonam. PFGE analysis indicated that the two isolates were distinguishable. Amplification and DNA sequencing confirmed the coexistence of blaNoM-1 , blasHv-12, qnrS1 and aac（6＇）-Ib-cr in both isolates. Transconjugants were detected with blaNoM-1 and qnrS1 simultaneously. Genetic environment analysis demonstrated that the blaNDM_l-bleMBL-trpF-dsbC-cutA1 structure was in consistence with those from known blaNDM_1 -carrying Klebsiella pneumoniae. Conclusion The blaNoM-1 in M. morganii isolates possiblely obtained from K. pneumoniae through translatable plasmids.