Serotypes and drug resistance of salmonella in commercial food in Pudong New Area from 2020 to 2022

Objective To understand the serotype distribution and drug resistance of salmonella contaminated in commercially available food.

Methods Salmonella detection， including the serotypes， was conducted in food products sold in Pudong New Area from 2020 to 2022. The antimicrobial susceptibility test of 15 antibiotics was conducted by the broth microassay.

Results A total of 118 salmonella strains were detected in 2 497 pieces of food， with a total detection rate of 4.7%. The dominant detection categories were poultry meat， livestock meat and aquatic products. The 118 salmonella strains could be divided into 24 serotypes， Salmonella enteritidis （26.4%）， Salmonella Typhimurium （16.2%） and Salmonella delpy （14.4%） were the main dominant types. Salmonella had the highest resistance rate to ampicillin （63.6%）， followed by tetracycline， chloramphenicol， cotrimoxazole and nalidixic acid. Among the three dominant serotypes， the multidrug resistance rate of Salmonella typhimurium was the highest （89.5%）， followed by Salmonella delpy （70.6%） and Salmonella enteritidis （61.3%）.

Conclusion Livestock， poultry meat， and aquatic products are seriously contaminated by salmonella with diverse serotypes. The livestock meat is mainly contaminated by Salmonella typhimurium and Salmonella delpy， and the poultry meat is mainly contaminated by Salmonella enteritidis. The drug resistance spectrum is wide and the multi-drug resistance rate is high. Different from the livestock and aquatic isolates， poultry meat-derived strains have high tolerance to ampicillin， nalidixic acid and polymyxin， and carry certain potential food safety risks.