Zhang F, Zhu D, Xie L, Guo X, Ni Y, Sun J
Department of Clinical Microbiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, 197 Ruijin No. 2 Road, Shanghai, 200025, China.
Eur J Clin Microbiol Infect Dis. 2015 Jun;34(6):1263-9. doi: 10.1007/s10096-015-2356-3. Epub 2015 Mar 11.
The molecular characteristics and epidemiology of carbapenemase-producing Escherichia coli (CPEC) isolates from Shanghai, China, were investigated using 21 imipenem-resistant E. coli isolates obtained from a Shanghai teaching hospital from 2011 to 2014. The presence of bla KPC, bla IMP, bla VIM, bla OXA-48, and bla NDM was assessed by polymerase chain reaction (PCR) amplification and sequencing. CPEC isolates were characterized by the Etest®, multilocus sequence typing (MLST), and pulse-field gel electrophoresis (PFGE). Plasmids carrying resistance genes were analyzed by conjugation experiments, replicon typing, plasmid MLST (pMLST), S1 nuclease PFGE (S1-PFGE), and Southern hybridization. The genetic environment of the resistance genes was determined by PCR and sequencing. Among the 21 E. coli isolates, 16 produced carbapenemases; of these, ten isolates transferred carbapenemase-encoding plasmids to recipient bacteria. Nine of the 16 isolates were clonally related, and their PFGE patterns were designated type A. ST131 was the predominant sequence type (11 isolates, 68.8 %); the H30 subclone comprised 81.8 % of the ST131 strains. In all three isolates, bla IMP-4 was located on 50-kb IncN plasmids. All but two bla KPC-2 genes were carried on IncF plasmids of various sizes. Hence, both clone-spread and horizontal transfer mediated the dissemination of carbapenemase-producing genes in the Shanghai isolates.
利用从上海一家教学医院2011年至2014年分离得到的21株对亚胺培南耐药的大肠埃希菌，对中国上海产碳青霉烯酶大肠埃希菌（CPEC）分离株的分子特征和流行病学进行了研究。通过聚合酶链反应（PCR）扩增和测序评估bla KPC、bla IMP、bla VIM、bla OXA - 48和bla NDM的存在情况。采用Etest®、多位点序列分型（MLST）和脉冲场凝胶电泳（PFGE）对CPEC分离株进行特征分析。通过接合实验、复制子分型、质粒MLST（pMLST）、S1核酸酶PFGE（S1 - PFGE）和Southern杂交分析携带耐药基因的质粒。通过PCR和测序确定耐药基因的遗传环境。在21株大肠埃希菌分离株中，16株产生碳青霉烯酶；其中，10株分离株将编码碳青霉烯酶的质粒转移至受体细菌。16株分离株中有9株克隆相关，其PFGE图谱被指定为A类型。ST131是主要的序列类型（11株，68.8%）；H30亚克隆占ST131菌株的81.8%。在所有3株分离株中，bla IMP - 4位于50 kb的IncN质粒上。除2个bla KPC - 2基因外，其余均携带在各种大小的IncF质粒上。因此，克隆传播和水平转移均介导了上海分离株中产碳青霉烯酶基因的传播。
