Current status of food microbial contamination in from Dehong Prefecture of Yunnan Province from 2015 to 2024

Objective: To analyze the results of food safety risk monitoring in Dehong Prefecture from 2015 to 2024, identify existing food safety hazards, and provide a scientific basis for the local authorities to formulate effective food regulatory measures and prevent and control foodborne diseases. Methods: In accordance with the National Manual for Risk Monitoring of Food Contaminants and Harmful Factors, the food samples comprised 102 condiments, 348 meat and meat products, 70 aquatic products, 70 quick-frozen rice and flour products, 446 catering foods, 34 edible fungi and their products, 84 fruits and their products, 53 soybean products, 18 nuts, seeds and their processed products, 54 frozen beverages, 33 eggs and egg products, 15 baked and fried foods, 40 vegetables and their products, and 10 other items (jelly) were randomly collected from 10 sales venues in Dehong Prefecture including convenience stores/retail shops, supermarkets, farmers’ markets, online stores, restaurants/ hotels, street stalls, snack bars, beverage shops, fast-food restaurants, and schools—a total of 10 sales venues. A total of 1377 food samples were collected and subjected to microbiological testing. A total of 17 testing items were performed, including sanitary indicator bacteria: Escherichia coli count, coliform count, total plate count, and mold count; and foodborne pathogens: Enterobacter sakazakii, Vibrio cholerae, Salmonella, Bacillus cereus, Staphylococcus aureus, Campylobacter jejuni, Listeria monocytogenes, diarrheagenic Escherichia coli, Clostridium perfringens, Vibrio parahaemolyticus, Burkholderia gladiata, Proteus, and Yersinia enterocolitica. Results: From 2015 to 2024, a total of 782 samples equaling to 1274 test instances were tested for sanitary indicator bacteria, with 411 positive test instances detected, resulting in a positivity rate of 32.26%; a total of 1377 samples equaling to 5128 test instances were tested for foodborne pathogenic bacteria, with 98 positive test instances detected, resulting in a positivity rate of 1.91%. The positive rate of hygienic indicator bacteria was the highest in 2022 (73.33%) (χ² = 97.61, P < 0.001), and the positive rate of foodborne pathogens was the highest in 2020 (3.61%) (χ² = 20.82, P = 0.013). The third quarter had the highest positivity rate for hygiene indicator bacteria (37.01%) (χ² = 18.06, P < 0.001), while there was no statistically significant difference in the positivity rates for foodborne pathogenic bacteria across different quarters (χ² = 7.19, P = 0.066). Beverage shops had the highest positivity rate for hygiene indicator bacteria (63.24%) (χ² = 128.21, P < 0.001), while farmers’ markets had the highest positivity rate for foodborne pathogens (3.75%) (χ² = 63.21, P < 0.001). Condiments had the highest positive rates for both hygiene indicator bacteria (62.20%) (χ² = 139.37, P < 0.001) and foodborne pathogens (5.38%) (χ² = 72.63, P < 0.001). The positivity rate for hygiene indicator bacteria in bulk foods (34.24%) was higher than that in prepackaged foods (27.12%) (χ² = 5.61, P = 0.018). Among the hygiene indicator bacteria, the positive rate for total colony count was the highest (68.48%) (χ² = 356.50, P < 0.001); among foodborne pathogens, the positive rate for Enterobacter sakazakii was the highest (25.81%) (χ² = 235.82, P < 0.001). Conclusion: The contamination levels of food hygiene indicator bacteria in foods sold in Dehong Prefecture from 2015 to 2024 were higher than those reported in previous studies. Relevant authorities should strengthen supervision during key periods such as the third quarter, at key sales locations such as restaurants and farmers’ markets, for key food categories such as condiments, and for bulk foods, and should intensify monitoring of total plate count and Enterobacter sakazakii.