摘要
[目的]了解猪源性肠球菌的耐药性及肠球菌对重金属锌抗性的现状,探究耐药基因和锌抗性基因的流行特征及其之间的相关性,为后期养殖临床上抗菌药物和ZnO的使用提供参考.[方法]采集了 395 份猪粪便样品,使用特异性选择培养基分离肠球菌,采用微量肉汤稀释法测定肠球菌分离株对9 种抗菌药物和ZnSO4 的敏感性,并采用PCR检测耐药基因和锌抗性基因.[结果]共分离出 348 株肠球菌,分离率为 88.10%.药物敏感性检测结果显示:肠球菌对红霉素的耐药率最高,达 96.81%,对万古霉素耐药率最低,仅为 0.71%.对锌敏感性的检测结果显示,对ZnSO4 的最小抑菌浓度(MIC)≥12 mmol·L-1的肠球菌占 52.13%.多重耐药性检测结果显示,肠球菌四重耐药占比最高,为 31.91%.PCR检测结果显示,锌抗性基因zntA的检出率为 37.93%,DNA旋转酶A亚单位基因gyrA的检出率为 92.79%,大环内酯类耐药基因mefA的检出率仅为 0.31%.相关性分析显示,锌抗性基因与核糖体保护蛋白编码基因tetS、四环素外排基因tetL呈显著正相关(P＜0.05),与四环素外排基因tetG呈显著负相关(P＜0.05),与gyrA、核糖体甲基化酶基因ermB呈负相关.[结论]重金属锌可能诱导猪肠道肠球菌的耐药以及多重耐药表型的出现,且抗菌药物可能会影响猪粪便中肠球菌的抗锌性.
Abstract
[Objective]The porcine Enterococcus resistance to heavy metal zinc and drug,its epidemiological feature and potential cor-relation between zinc and drug resistance genes were analyzed to provide reference for the use of antimicrobial drugs and ZnO in breed-ing.[Method]Enterococcus were isolated from 395 pig stool samples with specific selection medium,and their sensitivity to 9 antimi-crobial drugs and ZnSO4 were determined by microdilution method.Meanwhile,the presence of drug and zinc resistance genes were i-dentified through PCR.[Result]A total of 348 Enterococcus isolates were obtained,with an isolation rate of 88.10% .The drug suscep-tibility testing of Enterococcus isolates showed the highest resistance to erythromycin at 96.81% and the lowest to vancomycin at only 0.71% .Multidrug resistance analysis revealed that Enterococcus isolates with quadruple resistance accounted for the highest proportion(31.91% ).The ZnSO4 sensitivity testing indicated that 52.13% of the isolates had a minimum inhibitory concentration(MIC)≥12 mmol·L-1.The zinc resistance gene zntA had the detection rate of 37.93% .The detection rate of gyrA gene encoding the A subunit of DNA gyrase was 92.79%,while that of macrolide resistance gene mefA was only 0.31% .Correlation analysis indicated that zinc resist-ance gene was significantly positively correlated(P＜0.05)with the tetS gene encoding ribosome protection protein and tetracycline ef-flux gene tetL,but negatively correlated with the tetracycline efflux gene tetG(P＜0.05),gyrA and rRNA methylase gene ermB.[Con-clusion]The heavy metal zinc may induce the development of resistance and multidrug-resistant phenotypes in enteric Enterococcus of swine,and antimicrobial drugs may also influence the zinc resistance of Enterococcus in pig feces.
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