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目的研究临床分离碳青霉烯类抗菌药物耐药肠杆菌科细菌中新德里金属β-内酰胺酶(NDM)及其亚型的分布及流行特点。方法收集医院2014年1月-2015年1月各种临床标本中分离碳青霉烯类耐药肠杆菌科细菌563株,结合改良Hodge试验、EDTA协同及增效试验与PCR扩增检测blaNDM基因;通过肠杆菌基因间重复一致序列聚合酶链反应(ERIC-PCR)及多位点序列分型(MLST)分析菌株之间的同源性,采用药物敏感性试验、接合试验、质粒图谱分析、特异性聚合酶链反应(PCR)扩增和序列分析等技术研究细菌新德里金属β-内酰胺酶耐药的分子机制。结果共筛选出45株产NDM菌株,其中肺炎克雷伯菌38株,包括NDM-1型37株、NDM-5型1株,大肠埃希菌7株,均为NDM-7型;所有菌株呈现多药耐药现象,且每株菌均携带多种耐药基因,其中blaCTX-M、blaTEM、blaSHV、qnrB、qnrS、acc(6′)-Ib、rmtB、armA等为最常见共同携带耐药基因;MLST分型显示,产NDM-1肺炎克雷伯菌主要分布于ST11、ST76、ST495、ST37、ST700及ST395型中,产NDM-5肺炎克雷伯菌仅为ST14型;21株产NDM菌株接合试验阳性,其中包括13株NDM-1型、1株NDM-5型及7株NDM-7型,部分质粒之间有着相似图谱,blaNDM均定位于约46kb大小IncX3质粒上。结论医院已出现多种NDM亚型,主要通过IncX3型质粒在肠杆菌科细菌中传播,存在克隆传播现象;此外,NDM亚型的出现也表明NDM或正处于快速进化过程中而导致其广泛传播。
Objective To study the distribution and epidemic characteristics of metal β-lactamase (NDM) and its subtype in Enterobacteriaceae resistant to carbapenem-resistant antibiotics. Methods A total of 563 strains of carbapenem-resistant enterobacteriaceae were collected from January 2014 to January 2015 in hospitals, and the blaNDM gene was detected with improved Hodge test, EDTA synergy and synergistic test and PCR amplification ; The homology between the strains was analyzed by repeated sequence homologous polymerase chain reaction (ERIC-PCR) and multiple site sequence typing (MLST) of Enterobacteriaceae. The drug susceptibility test, conjugation test, plasmid map analysis, Specific polymerase chain reaction (PCR) amplification and sequence analysis techniques to study the molecular mechanism of bacterial β-lactamase resistance in New Delhi. Results A total of 45 strains of NDM were screened, of which 38 strains were Klebsiella pneumoniae, including 37 strains of NDM-1, 1 strain of NDM-5 and 7 strains of Escherichia coli. All strains were NDM-7. The results showed that there were many multidrug resistance genes in each strain, of which blaCTX-M, blaTEM, blaSHV, qnrB, qnrS, acc (6 ’) - Ib, rmtB and armA were the most common carriers Klebsiella pneumoniae producing NDM-1 Klebsiella pneumoniae mainly distributed in ST11, ST76, ST495, ST37, ST700 and ST395 type, producing NDM-5 Klebsiella pneumoniae was only ST14 type; 21 strains Strains of NDM-producing strains were positive, including 13 strains of NDM-1, 1 strain of NDM-5 and 7 strains of NDM-7. Some of the plasmids showed a similar pattern, blaNDM was located on the about 46kb IncX3 plasmid. Conclusion There are many subtypes of NDM in the hospital, which mainly spread in Enterobacteriaceae bacteria through IncX3 plasmid. Clonal transmission also exists in the hospital. In addition, the appearance of NDM subtypes also indicates that NDM is in the process of rapid evolution and leads to its widespread spread .