Acta Veterinaria et Zootechnica Sinica ›› 2021, Vol. 52 ›› Issue (9): 2650-2659.doi: 10.11843/j.issn.0366-6964.2021.09.029

• BASIC VETERINARY MEDICINE • Previous Articles     Next Articles

Prevalence of Antimicrobial Resistance and Virulence Factors in Enterococci from Poultry Farms in Guangdong Province

ZHANG Jing, CAI Ping, HE Yizhuo, CHEN Weitao, HUANG Yuchen, JIANG Hongxia*   

  1. National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
  • Received:2021-01-06 Online:2021-09-23 Published:2021-09-26

Abstract: The subtypes, antimicrobial resistance, virulence genes of enterococci isolated from poultry farms in Guangdong province were investigated and analyzed, aimed to provide theoretical basis for the control of resistance spread of animal origin enterococci and public health. A total of 493 intestinal samples were collected from 4 poultry farms in Guangdong province in 2018 for isolation and identification of E. faecalis and E. faecium. All the isolates were characterized by antimicrobial susceptibility using the agar dilution method, detection of antimicrobial resistance genes and virulence genes by PCR. Results were as follows:1) The results showed that a total of 125 isolates were obtained, including 84 E. faecalis (66 from chicken and 18 from duck) and 41 E. faecium from chicken intestinal samples. 2) The strains were almost all resistant to tetracycline, doxycycline, erythromycin. The antimicrobial resistance rates of florfenicol and chloramphenicol were as high as 89.60% and 74.40%, respectively. In general, the antimicrobial resistance rate of E. faecium was higher than that of E. faecalis, and the resistance rate for ciprofloxacin and linezolid in E. faecalis was higher than that in E. faecium. The resistance rate to linezolid was significantly higher in E. faecalis from duck (94%) than that from chicken (39.4%). However, all E. faecium were susceptible to linezolid. One E. faecalis strain from the chicken sample was resistant to vancomycin. 3) The detection rate for resistant genes in E. faecium was higher than that in E. faecalis, and the detection rate in duck isolates was higher than that in chicken isolates. Genes tetL, fexA and ermB were the most popular, with detection rates above 90%, followed by optrA (73.60%), and poxtA and fexB, being less than 20%. The cfr gene was detected in 3 E. faecalis from duck. 4) Among virulence genes tested, efaA was the most prevalent, with a detection rate of 63.04% (58/92), followed by gelE (54.35%, 50/92), ace (47.83%, 44/92) and asal (44.57%, 41/92). The strains resistant to CIP and HLAR and those harboring cfr mostly carried the virulence genes aggA, asal, gelE or ace. Enterococci from poultry farms presented serious antimicrobial resistance, and particularly strains from ducks demonstrated a high resistance rate to Linezolid. Antimicrobial-resistant genes and virulence genes are prevalent and diverse. Genes conferring resistance antimicrobials relevant to human medicine have also been detected. Therefore, it is necessary to strengthen the monitoring of enterococci resistance in poultry farms.

Key words: E. faecalis, E. faecium, antimicrobial resistance genes, virulence genes

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