To investigate the prevalence distribution and antimicrobial resistance of foodborne pathogens in diarrhea outpatient clinic in Qingpu District, Shanghai, from 2023 to 2025.

Rectal swabs and case data were collected from eligible diarrhea outpatients at 3 hospitals and 8 community health service centers in Qingpu District. Foodborne pathogens, including Salmonella, Vibrio parahaemolyticus and 5 kinds of categories of diarrheagenic Escherichia coli, were isolated and identified by laboratory diagnosis. The antimicrobial susceptibility to 17 kinds of antibiotics of 10 classes was determined using the broth microdilution method. Epidemiological characteristics and antimicrobial resistance profiles of the pathogens were statistically analyzed with SPSS 27.0.

A total of 110 strains of foodborne pathogens were detected from 974 anal swab samples of diarrhea cases during 2023—2025, including 56 strains of 5 categories of diarrheagenic Escherichia coli, 30 strains of Vibrio parahaemolyticus and 24 strains of Salmonella. The annual detection rates were 6.46% (34/526), 15.29% (26/170)and 17.99% (50/278), respectively, showing a statistically significant difference (χ²=27.39, P<0.001). The detection rate was 11.60% (61/526) in males and 10.94% (49/447) in females, with no statistically significant difference(χ²=0.105, P=0.746>0.05). There was a statistically significant difference in detection rates among different seasons(χ²=65.324, P<0.001), with the highest detection rate in the third quarter (summer) (21.65%, 63/291). Antimicrobial susceptibility testing was performed on the 110 strains mentioned above. Marked differences were observed in the antimicrobial resistance profiles among different foodborne pathogens, and multidrug resistance was found in Salmonella strains. Among the 5 kinds of pathotypes of diarrheagenic Escherichia coli, the highest antimicrobial resistance rate was detected against ampicillin (a penicillin), reaching 76.79%. The resistance rate of Vibrio parahaemolyticus to polymyxin E showed an upward trend over the three-year period, with annual resistance rates of 0%, 8.00% and 46.15%, respectively. The difference in resistance rates among the 3 years was statistically significant(χ²=81.843, P<0.05). Salmonella strains exhibited high resistance rates to cotrimoxazole (100.00%),ampicillin/sulbactam (54.17%), tetracycline (58.33%) and streptomycin (54.17%). Salmonella strains showed high resistance rates to cotrimoxazole (100.00%), ampicillin/sulbactam (54.17%), tetracycline (58.33%) and streptomycin(54.17%). The proportion of multidrug-resistant strains (defined as resistance to 3 or more classes of antibiotics)increased annually, and multidrug-resistant strains accounted for 58.3% of all resistant isolates in 2025.

From 2023 to 2025, foodborne pathogens in Qingpu District, Shanghai are mainly prevalent in summer, and the annual positive detection rate increased year by year, indicating that more attention should be paid to food hygiene and health. The drug resistance profiles varied significantly among different foodborne pathogens. Clinicians should select sensitive and appropriate antibiotics based on diarrhea symptoms, combine with the characteristics and drug resistance of different pathogens. Meanwhile, strengthening food hygiene supervision and health education is necessary to control and reduce the incidence of foodborne pathogen-induced diarrhea.