儿科患者感染大肠埃希菌耐药性分析及其耐药基因与可移动遗传元件研究

Analysis of the drug resistance of Escherichia coli infecting pediatric patients and study of its drug resistance genes and mobile genetic elements

目的研究儿科患者感染大肠埃希菌的耐药性及其耐药基因与可移动遗传元件的分布情况,为儿科患者抗感染治疗及致病菌耐药性的控制提供指导。方法收集本院2014年1月至2014年12月就诊的儿科患者临床标本,经分离、鉴定共获得大肠埃希菌201株。采用K-B法进行药敏试验,根据2015年CLSI标准判定结果。提取大肠埃希菌基因组DNA并设计耐药基因、可移动遗传元件扩增引物,通过PCR扩增检测其分布情况。结果药敏试验显示大肠埃希菌对阿米卡星、庆大霉素、氨苄西林、头孢唑林、头孢呋辛、头孢吡肟、头孢噻肟、头孢他啶、环丙沙星、妥布霉素、左氧氟沙星、亚胺培南、亚胺培南/西司他丁的耐药率分别为15.92%、33.83%、100.00%、64.68%、47.76%、4.98%、36.82%、18.91%、48.26%、38.81%、50.75%、12.94%和0.00%。PCR扩增ISCR1、IMP、tnpU、TEM、CTX-M-1、NDM-1、ant(3'')-Ⅰ、traA、qnr、aac(3)-Ⅱ、IS26、intⅠ1和SHV基因大小分别为475、587、403、535、891、287、284、272、240、237、387、373和305bp;IMP、CTX-M-1、TEM、SHV、NDM-1、aac(3)-Ⅱ、ant(3')-Ⅰ、qnr、intⅠ1、IS26、traA、tnpU和ISCR1基因阳性率分别为8.96%、46.77%、55.72%、42.79%、3.98%、48.76%、29.85%、52.74%、54.73%、90.05%、80.60%、19.90%和39.80%。结论儿科患者感染大肠埃希菌除了对亚胺培南/西司他丁敏感外,对其余检测药物均耐药,其耐药性的产生与其耐药基因及遗传元件的分布情况关系密切。

Objective The drug resistance of Escherichia coli infecting pediatric patients and its drug resistance genes and mobile genetic elements were studied to provide guidance for treatment of infections in pediatric patients and to limit the development of drug resistance. Methods Clinical samples from pediatric patients at this hospital were collected between January 2014 and December 2014.E.coli was isolated and identified,yielding a total of 201 strains of E.coli.A drug sensitivity test was conducted using the K-B method,and the results were judged in accordance with the 2015 guidelines of the CLSI.Genomic DNA of E.coli was extracted and primers were designed for amplification of drug resistance genes and PCR products were amplified to test for mobile genetic elements. Results Analysis of drug resistance indicated that E.coli resistance to amikacin was 15.92%,its resistance to gentamicin was 33.83%,its resistance to ampicillin was 100.00%,its resistance to cefazolin was 64.68%,its resistance to cefuroxime was 47.76%,its resistance to cefepime was 4.98%,its resistance to cefotaxime was 36.82%,its resistance to ceftazidime was 18.91%,its resistance to ciprofloxacin was 48.26%,its resistance to tobramycin was 38.81%,its resistance to levofloxacin was 50.75%,its resistance to imipenem was 12.94%,and its resistance to imipenem-cilastatin was 0.00%.PCR amplification revealed that the ISCR1 gene was 475 bp in length,the IMP gene was 587 bp in length,the tnpU gene was 403 bp in length,the TEM gene was 535 bp in length,the CTX-M-1gene was 891 bp in length,the NDM-1gene was 287 bp in length,the ant（3’）-I gene was 284 bp in length,the traA gene was 272 bp in length,the qnr gene was 240 bp in length,the aac（3）-II gene was 237 bp in length,the IS26 gene was 387 bp in length,the int I gene was 373 bp in length,and the SHV gene was 305 bp in length.Of the E.coli isolates,8.96% tested positive for IMP,46.77% tested positive for CTX-M-1,55.72%tested positive for TEM,42.79%tested positive for SHV,3.98% tested positive for NDM-1,48.76% tested positive for aac（3）-II,29.85%tested positive for ant（3’）-I,52.74%tested positive for qnr,54.73%tested positive for intI1,90.05%tested positive for IS26,80.60%tested positive for traA,19.90%tested positive for tnpU,and 39.80%tested positive for ISCR1. Conclusion The E.coli infecting pediatric patients had developed resistance to the tested drugs except for imipenem-cilastatin,and the development of this drug resistance was closely related to the distribution of drug resistance genes and mobile genetic elements.