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Chinese Agricultural Science Bulletin ›› 2023, Vol. 39 ›› Issue (8): 112-118.doi: 10.11924/j.issn.1000-6850.casb2022-0244

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Prevalence and Drug Resistance of ESBLs-Producing Salmonella Isolated from Different Poultry

LI Cuihan1,2(), ZHAO Jianmei1, ZUO Xiuli3, LIU Na1, WANG Juan1, LIU Junhui1, WANG Lin1, ZHANG Qingqing1, HUANG Xiumei1, GAO Yubin1, WANG Junwei1(), QU Zhina1()   

  1. 1 China Animal Health and Epidemiology Center, Qingdao, Shandong 266032
    2 College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030
    3 Junan Agriculture and Rural Affairs Bureau, Linyi, Shandong 276600
  • Received:2022-04-02 Revised:2022-10-09 Online:2023-03-15 Published:2023-03-14

Abstract:

By understanding the prevalence and drug resistance of Salmonella carried by different poultry in Jiaodong area, the study aims to provide evidence for effective prevention and control of the epidemic transmission of Salmonella in poultry and curb its drug resistance. Conventional bacterial isolation and culture, mass spectrometry, PCR method and micro-broth dilution method were adopted, 3150 cloacal swabs collected from poultry farms in five regions of Jiaodong from August to October in 2021 were used to isolate and identify Salmonella, and carry out serotype identification, antimicrobial susceptibility test and detection of major drug resistance genes to β-lactams, and statistical methods were used to analyze significant differences. (1) A total of 194 Salmonella strains (6.16%) were isolated. The Salmonella carrying rate of waterfowl (14.36%) was higher than that of broilers (5.04%) and laying hens (1.15%). (2) S. Enteritidis (38.14%), S. Kentucky (21.65%), S. Senftenberg (14.95%), S. Indiana(12.37%), and S. Typhimurium (8.76%) were the main serotypes of Salmonella. Broilers and waterfowl (each 7 species) had more Salmonella serotypes than laying hens (3 species), but S. Enteritidis was dominant in all of them. (3) 110 strains of poultry Salmonella were relatively strong resistant to ampicillin, sulfisoxazole and tetracycline (58.18%-77.27%). Meropenem-resistant strains were not detected. Strains isolated from waterfowl and broilers were more resistant than those from laying hens, especially to amoxicillin/clavulanate (P=0.031) and tetracycline (P=0.007). (4) 81 strains (73.64%) of poultry Salmonella were multi-drug resistant (MDR), with a total of 43 drug resistance spectrum types. The drug resistance spectrum of strains isolated from broilers (25 species) and waterfowl (22 species) was much more than that of laying hens (8 species). (5) blaCTX-M (70.00%), blaTEM (51.82%) and blaOXA (26.36%) were detected in 110 Salmonella strains, the common drug resistance gene combination type was blaCTX-M+blaTEM, and there was a certain relationship between drug resistance genes and phenotypes (P≤0.001). This shows that the poultry in Jiaodong area all carry a certain proportion of Salmonella, but there are differences in the prevalence among different breeds of poultry. There are also some differences in the types of serotypes carried by different poultry, but S. Enteritidis is the most common serotype. The drug resistance of strains is more serious, and the drug resistance spectrum is complex and diverse. The resistance of poultry Salmonella to β-lactams is mainly caused by the expression of blaCTX-M+blaTEM gene.

Key words: poultry, Salmonella, serotype, ESBLs, prevalence, drug resistance