Contamination and drug susceptibility characteristics of Yersinia enterocolitica in retail foods in Hangzhou, Zhejiang

Objective To investigate the contamination level and drug susceptibility of Yersinia enterocolitica in retail food in Hangzhou, Zhejiang province.

Methods Various types of foods were collected from retail markets in districts and counties of Hangzhou in 2019, 2021 and 2022, and Y. enterocolitica was isolated, purified and identified, and virulence genes were detected. All the isolates were tested for drug susceptibility by the broth dilution method, and their drug resistance characteristics and spectrum were analyzed.

Results A total of 460 food samples were collected, from which 134 strains of Y. enterocolitica were isolated and identified, with a detection rate of 29.13%. The detection rate was 41.00% in poultry meat and products and 37.43% in livestock meat and products. All the strains carried no ystA, ail, virF, and yadA genes, while 131 strains carried ystB gene (97.76%). Drug susceptibility analysis showed that the isolates were resistant to 14 antibiotics, and the resistance rate to cefazolin was highest (98.51%), followed by ampicillin (45.52%), nalidixicacid (23.88%), cefoxitin (12.69%). The resistance rates to another 10 antibiotics ranged from 0.75% to 5.00%. In addition, 2 isolates were polymyxin B resistant. The multidrug-resistance rate was 23.88%, and 9.70% of the isolates were resistant to four or more antibiotics. The drug resistance spectrum varied. One isolate was resistant to 7 antibiotics. Intergroup analysis found that the sensitive rates to ampicillin and cefoxitin were significantly higher in 2022 than in 2021.

Conclusion This study found the severe contamination of Y. enterocolitica in retail foods in Hangzhou, especially in poultry and livestock meat products. All the isolates were non-pathogenic, but the ystB gene carrying rate was obviously higher compared with previous studies. In addition, this study found that the Y. enterocolitica isolates was resistant to polymyxin, indicating the need to strengthen the surveillance for Y. enterocolitica and its drug resistance characteristics in various foods.