苍蝇中产耐NDM型碳青霉烯类肠杆菌的流行情况与耐药性分析

The Prevalence of NDM-Carbapenem-resistant Enterobacteriaceae (NDM-CRE) in Flies, and Analysis of Drug Resistance for NDM-CRE

为明确苍蝇对产NDM型碳青霉烯类耐药肠杆菌(NDM-CRE)传播的作用,对2016年9月-2017年9月采集于青岛地区某肉鸡养殖场周边的苍蝇进行NDM-CRE的流行情况与耐药性分析。通过细菌分离,16S rRNA鉴定与bla NDM耐药基因的确认,从120份苍蝇样品中分离出31株碳青霉烯耐药菌株(分离率为25.8%),其中NDM-CRE 16株(分离率为13.3%),分别为大肠杆菌10株(分离率为8.3%)、弗氏柠檬酸杆菌5株(分离率为4.2%)和肺炎克雷伯菌1株(分离率为8.3%)。对16株NDM-CRE进行NDM亚型鉴定,确认10株为bla NDM-5,6株为bla NDM-9;对其进行16种抗菌药物敏感性测试,结果显示,所有分离株除对替加环素敏感外,对氨苄西林、阿莫西林-克拉维酸钾(2∶1)、美罗培南、头孢唑啉、头孢西丁、头孢噻呋、四环素、土霉素和复方新诺明均耐药;85%以上的分离株对庆大霉素(87.5%)、氟苯尼考(93.8%)、氯霉素(93.8%)和恩诺沙星(87.5%)耐药;46.7%的分离株对氨曲南耐药;18.8%的分离株对多黏菌素E耐药;所有分离株对至少11种抗菌药物耐药,以耐14种抗菌药物菌株最多(n=6)。此外,对分离菌株进行12种耐药基因检测,结果发现,其至少携带5种耐药基因(bla NDM,bla TEM-1,sul 1,sul 2,floR),耐药机制较复杂。研究结果表明,养殖场周边的苍蝇可作为NDM耐药基因的重要载体,可能促进了养殖场、环境及相关人群中NDM-CRE的传播,对养殖产业的健康发展和公共卫生安全具有较大的威胁,有必要对其进行消除。

In order to clarify the effect of flies on the transmission of NDM-Carbapenem-Resistant Enterobacteriaceae(NDM-CRE),this study investigated the prevalence of NDM-CRE in flies,and the samples were collected from a broiler farm in Qingdao from September 2016 to September 2017.A total of 31 carbapenem-resistant bacteria(CRB)were obtained from 120 flies through bacterial separation and 16S rRNA sequence identification,in which 16 NDM-producing CRE(ten Escherichia coli,five Citrobacter freundii and one Klebsiella pneumonia)were obtained.In addition,two bla NDM variant genes,bla NDM-5 and bla NDM-9 were identified in 10 and 6 NDM-CRE isolates,respectively.The susceptibility testing showed that all isolates were sensitive to tigecycline but resistant to ampicillin,amoxicillin-clavulanate potassium(2∶1),meropenem,cefazolin,cefoxitin,ceftiofur,tetracycline,oxytetracycline,and cotrimoxazole;More than 85%isolates were resistant to gentamicin(87.5%),florfenicol(93.8%),chloramphenicol(93.8%),and enrofloxacin(87.5%);46.7%isolates showed resistance to aztreonam;18.8%isolates were resistant to polymyxin E.All isolates were resistance to at least 11 antibiotics,and most of the isolates(n=6)exhibited resistant to 14 antimicrobial agents.The detection of 12 resistance genes in all isolates revealed that it carried at least five resistance genes(bla NDM,bla TEM-1,sul 1,sul 2,floR),indicating that the mechanism of antimicrobial resistance was complicated.The results show that the flies closely surrounding the farm play as an important vector for bla NDM genes,which may promote the spread of NDM-CRE in farms,and its associated environment and population,and become a great concerns for both breeding industry and public health.Further efforts for eliminating the flies carrying NDM are needed.