China Animal Husbandry and Veterinary Medicine ›› 2022, Vol. 49 ›› Issue (7): 2788-2795.doi: 10.16431/j.cnki.1671-7236.2022.07.037

• Basic Veterinary Medicine • Previous Articles     Next Articles

Establishment of the Epidemiological Cut-off Values of Enterococcus Isolated from Animals for Antimicrobial Growth Promoters

YANG Yuying1,2, WANG Shaolin1   

  1. 1. College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
    2. Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
  • Received:2021-12-29 Online:2022-07-05 Published:2022-06-29

Abstract: 【Objective】 This study was aimed to establish the epidemiological cut-off values of Enterococcus isolated from animals for antimicrobial growth promoters and further to understand the resistance rate of animal-derived Enterococcus to antimicrobial growth promoters from 2019 to 2021.【Method】 The MICs of Enterococcus isolated from breeding farms in Beijing,Hebei,Sichuan,Shanxi,Shaanxi and Inner Mongolia from 2019 to 2021 to seven antimicrobial growth promoters (kitasamycin,flavomycin,enramycin,nasipeptide,averamycin,viginiamycin and bacitracin) were tested.According to the method specified in CLSI-VET,the non-linear regression simulation of MIC distribution data was carried out using the statistical tool ECOFFinder.The drug resistance rate of Enterococcus from animals to 7 kinds of antibacterial growth promoters was calculated by the epidemiological cut-off values under 95% confidence interval.【Result】 The epidemiological cut-off values of kitasamycin,flavomycin,enramycin,narceptide,averamycin,virinomycin and bacitracin were 8,8,8,0.25,8,8 and 32 μg/mL,respectively.Based on this,the drug resistance rates calculated were 64.38%,34.48%,80.06%,14.69%,19.06%,50.69% and 24.96%,respectively.Among them,Enterococcus was most resistant to enramycin,kitasamycin and virginiamycin,but most sensitive to nazeptide.In the statistics from 2019 to 2021,the drug resistance rates of flavomycin and bacitracin decreased relatively obviously.【Conclusion】 This study established the epidemiological cut-off values of animal-derived Enterococcus against seven antimicrobial growth promoters commonly used in aquaculture. It could be used as a preliminary criterion for determining the sensitivity and resistance of animal-derived Enterococcus to antimicrobial growth promoters and provide a scientific basis for further establishing drug resistance points and monitoring the changes of drug resistance of animal-derived Enterococcus to antimicrobial growth promoters.

Key words: Enterococcus; antimicrobial growth promoters; ECOFFs; drug resistance

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