鸡源携带黏菌素耐药基因mcr-1大肠杆菌的流行情况及耐药性研究

Prevalence and Drug Resistance Analysis of Escherichia coli with Colistin Resistance Gene mcr-1 from Chickens

【目的】调查不同年份不同地区携带质粒介导的黏菌素耐药基因mcr-1大肠杆菌的流行情况,并分析其耐药性。【方法】2017、2018、2019、2021年从河南省开封、南阳以及江西省赣州随机收集鸡肛门拭子和粪便样品,对其进行细菌分离培养,挑取疑似菌落进行革兰染色镜检,利用药敏试验检测分离株对常见14种抗菌药的敏感性及多重耐药情况,通过PCR扩增分离株携带的临床常见耐药基因。采用多重PCR对mcr-1基因阳性分离株进行种族系统进化分析。【结果】共分离到724株鸡源大肠杆菌,其中河南省364株,江西省360株。724株分离株对四环素耐药率最高(93.65%),其次为氟苯尼考(87.98%),对阿米卡星和黏菌素较敏感,耐药率分别为4.83%和18.51%。724株菌株中共有96株分离株携带mcr-1基因,其均呈现多重耐药性,对多西环素和氟苯尼考的耐药率均为96.88%。96株携带mcr-1基因分离株中有27株同时携带其他临床耐药基因,其中14株携带fosA3基因,11株携带bla CTX-M-1G基因,13株携带bla CTX-M-9G基因,3株携带bla NDM基因,有11株同时携带磷霉素耐药基因fosA3和超广谱β-内酰胺酶基因。种族系统进化分析结果显示,87株携带mcr-1基因分离株为A群,4株为B1群,5株为D群。【结论】不同年份不同地区鸡源大肠杆菌携带mcr-1基因存在差异,mcr-1基因阳性菌株多重耐药情况较明显,部分携带mcr-1基因的分离株同时携带其他临床耐药基因。持续监测mcr-1基因在不同区域和不同领域的流行情况,有助于更好地了解细菌耐药性的形成和传播规律,进而采取有效的防控措施。

【Objective】The aim of this experiment was to investigate the prevalence of Escherichia coli with plasmid-mediated colistin resistance gene mcr-1 in different regions and years,and to analyze its drug resistance.【Method】In 2017,2018,2019 and 2021,anal swabs and fecal samples of chicken were randomly collected from Kaifeng and Nanyang in Henan province and Ganzhou in Jiangxi province.The bacteria were isolated and cultured,and the suspected colonies were selected for Gram staining microscopy.Susceptibility test was used to detect the sensitivity and multiple drug resistance of the isolates to 14 common antibacterial drugs.Common clinical drug resistance genes were isolated by PCR amplification.Phylogenetic analysis of mcr-1 gene positive isolates was performed by multiplex PCR.【Result】A total of 724 strains of Escherichia coli of chicken origin were isolated,including 364 in Henan province and 360 in Jiangxi province.The resistance rate of 724 isolates to tetracycline was the highest(93.65%),followed by flufenicol(87.98%),and amicacin and colistin were more sensitive(4.83%and 18.51%,respectively).96 isolates of 724 strains carried mcr-1 gene,and all of them showed multi-drug resistance,with 96.88%resistance rates to doxycycline and flufenicol.Among the 96 isolates carrying mcr-1 gene,27 carried other clinical drug resistance genes,among which 14 carried fosA 3 gene,11 carried bla CTX-M-1G gene,13 carried bla CTX-M-9G gene,and 3 carried bla NDM gene.11 isolates carried both fosA 3 andβ-lactamase genes.Phylogenetic analysis showed that 87 isolates carrying mcr-1 gene belonged to group A,4 isolates belonged to group B1,and 5 isolates belonged to group D.【Conclusion】There were differences in the mcr-1 gene Escherichia coli of chickens from different years and regions.mcr-1 gene positive isolates showed obvious multi-drug resistance,and some isolates carrying mcr-1 gene also carried other clinical drug resistance genes.Continuous monitoring of the prevalence of mcr-1 gene in different regions and fields was helpful to better understand the formation and spread of bacterial resistance,and then took effective prevention and control measures.