Acta Veterinaria et Zootechnica Sinica ›› 2024, Vol. 55 ›› Issue (1): 290-299.doi: 10.11843/j.issn.0366-6964.2024.01.027

• PREVENTIVE VETERINARY MEDICINE • Previous Articles     Next Articles

Isolation, Identification, Pathogenicity and Drug Susceptibility of Mycoplasma gallisepticum from Dead Chicken Embryos in Large-scale Chicken Farms in Guangdong Province

CHEN Yuetong1,2, LIU Xiaohan1,3, WANG Zhiyang1, ZHAO Yuxin1, ZHOU Tiezhong2, HU Zengjin1, ZHU Yue1, WANG Shaohui1, TIAN Mingxing1, DING Siyu4, QI Jingjing1*, YU Shengqing1*   

  1. 1. Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China;
    2. College of Animal Husbandry and Veterinary Medicine, Jinzhou Medicine University, Jinzhou 121000, China;
    3. Shandong Vocational Animal Science and Veterinary College, Weifang 261000, China;
    4. Yangzhou Youjiachuang Biotechnology Co., Ltd, Yangzhou 225261, China
  • Received:2023-04-19 Online:2024-01-23 Published:2024-01-24

Abstract: The aim of this study was to isolate Mycoplasma gallisepticum (MG) from dead chicken embryos in a large-scale chicken farm in Guangdong, and genetic evolution analysis, pathogenicity and drug susceptibility tests were carried out. Isolation of MG were conducted, then the isolated strains were identified by colony observation, serological test and 16S rRNA sequencing. At the same time, the isolated strains were used to infect chicken embryos and SPF chickens, and were subjected to antimicrobial susceptibility tests. Under the microscope, the colonies showed typical ‘poached egg’. Plate agglutination test showed that it had agglutination reaction with MG positive serum and did not react with MS positive serum. The 16S rRNA sequencing showed that the homology of each isolate with MG was 99.9%, so the isolates were identified as MG strains. Each isolate was used to infect 7-day-old SPF chicken embryos, and the results showed that most of the infected chicken embryos died near hatching. After 3 weeks of infection in 3-week-old SPF chickens, significant pathological changes were found in the air sac of chickens, indicating that it had strong pathogenicity. The drug sensitivity test showed that the 5 isolates were highly sensitive to warnimulin hydrochloride, doxycycline, tywanmycin and tymectin, and were resistant to tilmicosin, tylosin, enrofloxacin, erythromycin, kitasamycin and lincomycin to varying degrees. Five MG isolates were successfully isolated from dead chicken embryos in a large-scale chicken farm in Guangdong province. All of the isolates could cause chicken embryo death and cause typical air sac inflammatory symptoms to SPF chickens, and they had varying degrees of resistance to multiple drugs. This study provides reference technical methods and guidance for the isolation, identification and drug selection for clinical MG, and also provides a research basis for the establishment of MG challenge model.

Key words: Mycoplasma galliscepticum, dead chicken embryos, isolation and identification, pathogenicity, drug susceptibility

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