Objective To understand the contamination of Bacillus cereus in catering food in Tai'an, Shandong province, and provide theoretical reference for the prevention and clinical treatment of food poisoning and infection of B. cereus.

Methods According to national standard GB 4789.14-2014, all the samples of catering food were used for B. cereus isolation and identification. Real-time fluorescent quantitative polymerase chain reaction was conducted to detect the genes of haemolysin BL, non-haemolytic enterotoxin (Nhe) and ces in isolated strains. According to the user manual, antibiotic susceptibility test was conducted.

Results A total of 282 samples of catering food were collected and tested in Tai'an from 2020 to 2023, and 45 strains of B. cereus were detected, with a total detection rate of 15.96%. The detection rate of B. cereus was highest (22.67%) in four kinds of catering food which were ordered online. In 45 strains of B. cereus, the carriage rate of gene of Nhe was 97.78%, the carriage rate of gene of haemolysin BL was 66.67% and no gene ces was detected. The sensitive rates of the isolates to ciprofloxacin, chloramphenicol, gentamicin, tetracycline, vancomycin and trimethoprim-sulfamethoxazole were higher than 80.00%, and the resistance rates to ampicillin and penicillin were 100.00%.

Conclusion B. cereus contamination was detected in catering food in Tai'an, and the virulence gene carrying rate was high in B. cereus. It is necessary to strengthen food safety supervision. Ampicillin and penicillin should not be used in the clinical and empirical treatments of B. cereus infection.