China Animal Husbandry and Veterinary Medicine ›› 2025, Vol. 52 ›› Issue (1): 470-480.doi: 10.16431/j.cnki.1671-7236.2025.01.043

• Basic Veterinary Medicine • Previous Articles    

Prevalence and Drug Resistance of Escherichia coli Isolated from Dairy Cows in Some Areas of Xinjiang

MA Hongpeng1,2, SHAO Wei2, LOU Xiaoxiao1,2, GAO Jiaojiao1,2, MA Xianlan1, CHEN He1, ZHENG Nan3, ZHAO Yankun1,3   

  1. 1. Xinjiang Agricultural Product Quality and Safety Laboratory, Agricultural Product Quality and Safety Risk Assessment Laboratory of the Ministry of Agriculture and Rural Areas (Urumqi), Institute of Agricultural Quality Standards and Testing Technology, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China;
    2. College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China;
    3. Key Laboratory for Quality & Safety Control for Milk and Dairy Products of Ministry of Agriculture and Rural Affairs, Institute of Animal Science of CAAS, Beijing 100193, China
  • Received:2024-03-14 Published:2024-12-30

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Abstract: 【Objective】 This study was aimed to investigate the prevalence and drug resistance of Escherichia coli in milk from diseased cows and environment of dairy farms in some regions of Xinjiang,and to provide basis for clinical drug use of Escherichia coli in this region. 【Method】 171 samples (55 milk samples from diseased cows and 116 environmental samples) from four intensive farms in some regions of Xinjiang were isolated and purified by plate scribing method,and the Escherichia coli isolates were identified by morphological observation,Gram staining microscopy, biochemical identification and molecular biology methods. The resistance phenotypes and resistance genes of 16 kinds of antibacterial drugs of Escherichia coli isolates were analyzed by broth dilution method and PCR method. 【Result】 A total of 45 strains of Escherichia coli were isolated from 171 samples,including 8 strains from milk samples from diseased cows with a separation rate of 14.55% (8/55),and 37 strains from environmental samples with a separation rate of 31.90% (37/116).All isolates were pink round colonies.Gram staining microscopy showed red,short rod Gram-negative bacteria.Biochemical identification results showed that lactose,mannitol,indigo matrix and MR were positive,while oxidase,H2S,VP and simonium citrate were negative,which was consistent with the biochemical characteristics of Escherichia coli.The results of drug susceptibility test showed that the Escherichia coli isolates showed different degrees of resistance to cephalothin,ampicillin,streptomycin and tetracycline,with resistance rates of 82.22%,48.89%,33.33% and 33.33%,respectively,while they showed high sensitivity to meropenem,kanamycin,gentamicin,ciprofloxacin and sulfamethoxazole,with sensitivity rates of more than 85.00%,including 16 Escherichia coli strains with multiple drug resistance.The multidrug resistance rate was 35.56%.The results of drug resistance gene detection showed that,β-lactams resistance gene blaTEM,aminoglycosides resistance genes addA1 and strA were 13.33%,6.66% and 11.11%,respectively.The positive rates of tetracycline resistance genes tetA and tetC were 13.33% and 33.33%,respectively. 【Conclusion】 Escherichia coli isolated from dairy cattle breeding sites in some regions of Xinjiang was highly resistant to β-lactam antibiotics and exhibited severe multidrug resistance.

Key words: dairy cow mastitis; Escherichia coli; susceptibility test; resistance genes

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