[Antimicrobial resistance analysis of Salmonella and diarrheagenic Escherichia coli isolated from food in China, 2023].

Objective: To investigate the antimicrobial resistance status of Salmonella and diarrheagenic Escherichia coli (E.coli) isolated from food samples across 31 provinces in China during 2023. Methods: From January to December 2023, 2 269 Salmonella and 1 146 diarrheagenic E.coli isolates were recovered from meat of livestock and poultry, aquatic products, and ready-to-eat foods collected from restaurants, cafeterias, farmers' markets, and supermarkets. Antimicrobial susceptibility of the isolates was determined using the microbroth dilution method, and resistance was interpreted according to the Clinical and Laboratory Standards Institute M100 2024 breakpoints. Results: The overall resistance rates were 78.71% (1 786/2 269) for Salmonella and 80.37% (921/1 146) for diarrheagenic E. coli. Salmonella and diarrheagenic E. coli isolates from raw poultry meat exhibited elevated resistance rates of 95.59% (434/454) and 90.27% (204/226), respectively.Both pathogens exhibited high resistance to ampicillin (AMP), tetracycline (TET), and chloramphenicol (CHL), with resistance rates of 60.33%, 57.16%, and 48.23% for Salmonella and 62.04%, 68.77%, and 54.42% for diarrheagenic E.coli, respectively. All isolates of both pathogens were susceptible to ceftazidime/avibactam. The multidrug resistance (MDR) rates were 57.29% (1 300/2 269) in Salmonella and 60.82% (697/1 146) in diarrheagenic E. coli. The predominant resistance profiles were AMP-CHL-trimethoprim-sulfamethoxazole (SXT)-TET-florfenicol in Salmonella and AMP-CHL-SXT-TET in diarrheagenic E.coli. The resistance rates of Salmonella isolates from Heilongjiang Province and Guizhou Province were 92.70% (127/137) and 92.45% (49/53), respectively, with a relatively high MDR rate in Guizhou Province (73.58%, 39/53). Among diarrheagenic E. coli, resistance rates of isolates from Shanghai and Gansu Province were 95.19% (99/104) and 90.00% (45/50), respectively, with a notable MDR rate in Shanghai (86.54%, 90/104). Conclusions: Salmonella and diarrheagenic E. coli isolated from various foods in China, particularly raw poultry meat, demonstrated high resistance rates to AMP, TET, and CHL, along with concerning levels of multidrug resistance. These findings highlight a significant public health concern and necessitate urgent attention and effective intervention strategies from relevant authorities.