辽宁地区奶牛乳房炎源大肠杆菌毒力基因及耐药基因检测分析

摘要

为了掌握辽宁地区规模奶牛场乳房炎源大肠杆菌携带的毒力基因和耐药基因,为奶牛养殖业提供更好的乳房炎防制方案,本研究采用PCR检测方法对辽宁地区多个规模奶牛场临床奶牛乳房炎奶样中分离的66株大肠杆菌进行了4种毒力基因和4种耐药基因的检测分析.结果发现,66株大肠杆菌中仅有1株未检出相关目的基因,其余65株中最少检出2种目的基因,最多检出7种目的基因.其中,毒力基因stx2e、eaeA、K99和astA的检出率分别为56.1%、47.0%、34.8%和31.8%,双重毒力基因的检出率达到43.9%,以eaeA/stx2e基因型的检出率最高;耐药基因sul3、sul1、cmlA及aacA4的检出率分别为87.9%、83.3%、40.9%和28.8%,双重耐药基因的检出率为36.4%,以sul1/sul3基因型检出率最高;三重耐药基因的检出率为37.9%,以cmlA/sul1/sul3检出率最高.本研究结果证实,辽宁地区奶牛乳房炎源大肠杆菌携带磺胺类耐药基因和氯霉素类耐药基因的比率较高,与大肠杆菌的耐药性有较直接的关系,该结果对于辽宁地区奶牛乳房炎的防制具有重要的指导意义,更具有重要的公共卫生意义.%In order to understand the virulence genes and drug resistance genes carried by E.coli strains from dairy cows with mastitis in large-scale dairy farms in Liaoning region, and also provide improved programs for control and treatment of mastitis to dairy farmers, 66 strains of E.coli isolated from milk of dairy cows with clinical mastitis in several large-scale farms in Liaoning region were examined to detect 4 virulence genes and 4 drug resistance genes using PCR methods.The results showed that none of the target genes was detected in only one strain, while at least 2 and up to 7 target genes were detected in the rest of 65 strains.The detection rates of the virulence genes stx2e, eaeA, K99 and astA were 56.1%, 47.0%, 34.8% and 31.8%, respectively.In addition, the detection rate of dual virulence gene reached 43.9%, in which the genotype with the highest detection rate was eaeA/stx2e.The detection rates of the drug resistance genes sul3, sul1, cmlA and aacA4 were 87.9%, 83.3%, 40.9% and 28.8%, respectively.And the dual resistance gene detection rate was 36.4%, in which the highest detection rate was sul1/sul3 genotype;Triple drug resistance gene detection rate was 37.9%, and cmlA/sul1/sul3 presented the highest detection rate.These results confirmed that the E.coli isolated from dairy cow mastitis in large-scale dairy farms in Liaoning region had high detecting rates of sulfonamide resistance genes and chloramphenicol resistance genes, which was directly related to the drug resistance of the E.coli.These results provided important guiding significance for the prevention and control of dairy cow mastitis in Liaoning region as well as the safety of public health.