Surveillance and analysis of microbial contamination in commercially available ready-to-eat foods in Songjiang District， Shanghai from 2017 to 2022

ObjectiveTo investigate the microbial contamination status of commercially available ready-to-eat (RTE) foods in Songjiang District of Shanghai, to verify the potential food safety hazards, so as to provide a scientific basis for the local regulation of RTE foods and the prevention of foodborne diseases.MethodsA total of 882 food samples from 9 categories of RTE foods were collected in Shanghai from 2017 to 2022. Salmonella, Listeria monocytogenes, Vibrio parahaemolyticus, Staphyloccus aureus and Bacillus cereus were detected according to the standard operating procedures in the Manual for China National Food Contamination and Harmful Factors Risk Monitoring, and which were determined with reference to relevant standards.ResultsA total of 77 samples were found to carry foodborne pathogens, with a total detection rate of 8.73%. Among the 5 foodborne pathogens, Bacillus cereus had the highest detection rate (8.35%), followed by Vibrio parahaemolyticus (5.05%), and the difference of detection rates among the 5 foodborne pathogens was statistically significant (χ2=112.307, P<0.001). Among the 9 categories of RTE food products, the detection rate of foodborne pathogens in RTE fermented/non-fermented soybean products was the highest (27.50%), followed by cold noodles (17.33%) and raw edible aquatic products (9.50%), and the difference in the detection rates of foodborne pathogens among different RTE food categories was statistically significant (χ2=45.909, P<0.001). The detection rate of foodborne pathogens in the third quarter of the year was 10.99%, significantly higher than that in other quarters (χ2=10.329, P=0.016). The detection rate of foodborne pathogens in samples from supermarkets was highest (15.08%), followed by snack bars (11.58%), with a statistically significant difference (χ2=14.108, P=0.015).ConclusionFoodborne pathogens contamination is found in commercially available RTE foods in Songjiang District of Shanghai, especially in RTE fermented/non-fermented soybean products, RTE cold noodles and raw edible aquatic products from supermarkets, snack bars and farm products markets during summer and autumn. Therefore, it is crucial to strengthen supervision and management to avoid the foodborne diseases.