犬源大肠杆菌新疆流行株鉴定及其耐药特征与毒力基因检测分析

Identification of canine Escherichia coli epidemic strains in Xinjiang, their drug resistance characteristics, and virulence gene detection

  • 摘要: 【目的】 鉴定犬源大肠杆菌新疆流行株,并进行耐药特征与毒力基因检测分析,为新疆地区犬源耐药菌株的针对性防控与临床合理用药提供理论依据。【方法】 2024年2—10月,在新疆采集犬源肛拭子样本(健康犬样本168份,患病犬样本287份)。对犬源大肠杆菌进行分离鉴定和分子分型分析,并检测药物敏感性和超广谱β-内酰胺酶(ESBLs)耐药基因。随后对的391株犬源大肠杆菌进行18种毒力基因的PCR检测,并筛选出携带毒力基因≥8的菌株进行小鼠致病性检测。【结果】共分离鉴定出大肠杆菌391株,B1群检出率最高,其次为A群、B2群,D群检出率最低。犬源大肠杆菌对β-内酰胺类药物氨苄西林的耐药率最高,其次为头孢噻肟和四环素,多重耐药菌株(同时对≥3类抗菌药物耐药)的检出率为66.75%,健康犬源与患病犬源大肠杆菌对15种抗生素的多重耐药情况无显著差异(P>0.05)。产ESBLs菌株的4种耐药基因的PCR检测结果显示,TEM基因携带率最高,其次为CTX-M基因,SHVOXA基因的检出率较低。391株犬源大肠杆菌共检出12种毒力基因,ompA基因检出率最高,其次为ibeBsodAyijPmatfimHiroN基因。小鼠致病性检测结果显示,不同流行株的致病力存在差异。【结论】犬源大肠杆菌新疆流行株以A群和B1群为主,耐药情况严峻,多重耐药现象普遍。大部分犬源大肠杆菌携带ESBLs耐药基因与多种毒力基因,且具有较强的致病性。产ESBLs的犬源流行株可能已在新疆地区宠物犬中广泛流行与传播,对公共卫生安全构成严重威胁。

     

    Abstract: 【Objective】 To identify canine Escherichia coli epidemic strains in Xinjiang, analyze their drug resistance characteristics and virulence genes, which could provide theoretical basis for targeted prevention and control of canine drug-resistant strains as well as rational clinical medication in Xinjiang. 【Method】 From February to October in 2024, a total of canine anal swab samples were collected in Xinjiang, including 168 samples from healthy dogs and 287 samples from sick dogs. Isolation, identification and molecular typing of canine Escherichia coli were performed. Drug susceptibility and extended-spectrum β-lactamase (ESBLs) resistance genes were subsequently detected. A total of 18 virulence genes were screened by PCR in the 391 obtained Escherichia coli isolates. Strains carrying ≥8 virulence genes were selected for pathogenicity tests in mice. 【Result】 A total of 391 Escherichia coli strains were isolated and identified. Group B1 showed the highest detection rate, followed by group A and group B2, while group D had the lowest rate. Canine Escherichia coli exhibited the highest drug resistance rate to ampicillin (a β-lactam antibiotic), followed by cefotaxime and tetracycline.The detection rate of multiple drug-resistant strains (resistant to ≥3 classes of antibiotics) reached 66.75%. No significant difference was observed in the multiple drug resistance against 15 antibiotics between Escherichia coli strains from healthy dogs and sick dogs (P>0.05). According to PCR detection,among the four ESBLs resistance genes in ESBLs-producing strains, TEM gene had the highest carrying rate, followed by CTX-M gene, while SHV and OXA genes presented relatively low detection rates. A total of 12 virulence genes were detected in the 391 canine Escherichia coli strains. The detection rate of ompA gene was the highest, followed by ibeB, sodAyijPmatfimH and iroN genes. Pathogenicity assays in mice revealed distinct virulence among different epidemic strains. 【Conclusion】 The canine Escherichia coli epidemic strains in Xinjiang belong to group A and group B1. Severe drug resistance and widespread multidrug resistance are observed in these strains. Most strains carry ESBLs resistance genes and multiple virulence genes with strong pathogenicity. ESBLs-producing canine Escherichia coli strains have likely spread extensively among pet dogs in Xinjiang, posing a serious threat to public health security.

     

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