Research Note: Changes in pathogenic characteristics and drug resistance of Salmonella in poultry meat in Jiading District, Shanghai from 2019 to 2021

To investigate the contamination status, serotype distribution, and drug resistance of Salmonella in poultry sold in Jiading District, Shanghai. Four types of raw poultry meats (chickens, ducks, geese, and pigeons) have been sampled from commercial markets, and potential Salmonella contamination has also been isolated and identified via serotype analysis. Furthermore, resistance of isolated Salmonella toward 14 commonly used antibiotics has also been conducted. Ninety-two Salmonella strains were isolated from 236 commercial poultry samples. The detection rates of Salmonella in pigeon, goose, duck, and chicken were 28.89, 44.44, 39.34, and 38.30%, respectively. The detection rate of Salmonella exhibits considerable variation across different years. The serotype composition of Salmonella in poultry demonstrates annual variability, undergoing significant changes from year to year. The majority serotypes of Salmonella have been revealed as S. Typhimurium, S. Enteritidis, and S. Agona. Relatively higher drug resistance was discovered with nalidixic acid, tetracycline, ampicillin and chloramphenicol, with drug resistance rate as 58.70, 53.25, 44.57, and 38.04%, respectively. Low drug resistance was revealed with cefotaxime, and completely sensitive to imipenem. Significant difference in drug resistance was noted in the Salmonella isolated from meats. Different serotypes of Salmonella strains have also revealed as difference in drug resistance. A total of 15.22% of Salmonella strains were nonresistant to any tested drugs. Multidrug-resistant strains accounted for 36.96% of isolated strains. The highest number of resistant antibiotics can reach 12 kinds of different antibiotics, Salmonella resistance is exhibiting a consistent upward trend overall. AMP-TET or CHL-CFZ drug resistance pattern suggested that the strain was multidrug resistant. The contamination of Salmonella in raw poultry meat samples in Jiading District, Shanghai is serious, and the drug resistance is increasing. The measures taken for epidemic prevention and control have a certain impact on the contamination of Salmonella in poultry meat. Therefore, monitoring and control should be strengthened.