China Animal Husbandry and Veterinary Medicine ›› 2023, Vol. 50 ›› Issue (2): 789-797.doi: 10.16431/j.cnki.1671-7236.2023.02.036

• Basic Veterinary Medicine • Previous Articles     Next Articles

Isolation,Identification and Drug Resistance Analysis of Staphylococcus aureus in Raw Milk in Some Areas of Xinjiang

MA Xiaojiao1,2,3, ZHAO Yankun2,3, SHAO Wei1, WU Yating2, LI Ming1,2, LIU Huimin3, MENG Lu3, CHEN He2   

  1. 1. Xinjiang Meat and Milk Herbivore Nutrition Laboratory, College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China;
    2. Agricultural Product Quality and Safety Risk Assessment Laboratory of the Ministry of Agriculture and Rural Areas (Urumqi), Xinjiang Agricultural Product Quality and Safety Laboratory, Institute of Agricultural Quality Standards and Testing Technology, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China;
    3. Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China
  • Received:2022-09-06 Online:2023-02-05 Published:2023-02-06

Abstract: 【Objective】 The purpose of the experiment was to investigate the prevalence and drug resistance of Staphylococcus aureus in raw milk in some areas of Xinjiang,and provide a theoretical basis for monitoring Staphylococcus aureus in raw milk in this area and ensure the quality and safety of raw milk.【Method】 A total of 110 raw milk samples were randomly collected from large-scale dairy farms in Northern and Southern Xinjiang. Staphylococcus aureus was isolated and identified from milk samples by enrichment culture,isolation and purification,Gram staining,biochemical identification and PCR.The phenotypic resistance and drug resistance genes of Staphylococcus aureus to 16 antimicrobial agents were analyzed by broth microdilution and PCR.【Result】 18 strains of Staphylococcus aureus were isolated from 110 milk samples.The isolated strains showed light yellow,smooth and convex round colonies.Gram staining microscopy showed purple,short chain arrangement of Gram-positive bacteria.The biochemical test results conformed to the biochemical characteristics of Staphylococcus aureus.The isolated strains were identified as Staphylococcus aureus by 16S rDNA and nuc gene PCR amplification,with a separation rate of 16.36%(18/110).Drug susceptibility results showed that Staphylococcus aureus isolates had high resistance rates to ampicillin,penicillin and sulfaisoxazole,with resistance rates of 100%,83.33% and 77.78% respectively,while they were highly sensitive to vancomycin,compound minophen,oxacillin,cefalotin,ceftiofur,rifaximin and ciprofloxacin,with sensitivity rates of 100%,100%,94.44%,94.44%,94.44%, 94.44% and 94.44%,respectively.Among them,14 strains of Staphylococcus aureus were multidrug resistant,and the multidrug resistance rate was 77.78%.The detection results of drug resistance genes showed that the detection rate of macrolide resistance gene ermB (50.00%) was the highest,followed by β-lactam resistance gene mecA (27.28%) and Sul1 (22.22%).【Conclusion】 The prevalence and drug resistance rate of Staphylococcus aureus isolated from raw milk obtained from dairy farms in Xinjiang were still relatively serious,and the phenomenon of multi-drug resistance existed,which emphasized the importance of monitoring the drug resistance of Staphylococcus aureus in raw milk.

Key words: raw milk; Staphylococcus aureus; antibiotics; multiple drug resistance; drug resistance gene

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