Objective  To reveal the antimicrobial susceptibility and drug-resistance genes characteristics of Yersinia enterocolitica from different sources in Jiangsu province during 2018−2021.

  Methods  Different kinds of specimens were collected for strain isolation, the isolated strains of Y. enterocolitica were evaluated by biochemical identification. All the isolates were tested for drug susceptibility to 15 kind antibiotics by the broth dilution method. The whole genome sequences of strains were scanned for drug resistance genes by Comprehensive Antibiotic Research Database (CARD).

  Results  From 2018 to 2021, a total of 6414 specimens were collected, and 132 strains (2.06%) of Y. enterocolitica were isolated and identified. Among them, 47 were isolated from diarrhea patients. The results of drug susceptibility analysis showed that all the strains were resistant to macrolide antibiotic azithromycin and penicillin antibiotic ampicillin, and sensitive to tigecycline and amikacin. There were different degrees of resistances (3.79%–38.64%) to 12 other kinds of antibiotics. A total of 42 drug-insensitive phenotypes were found, and 65.90% (87/132) of the strains were not sensitive to ≥3 antibiotics. Based on sequencing analysis, 8 types of 16 drug resistance genes were found, i.e. β-lactamase genes blaA, blaB and bla_OXA-10, aminoglycoside resistance genes aac, aad and aph, quinolone resistance gene qnr, tetracycline resistance gene tet, amide alcohol resistance gene floR, cmlA and cat, sulfonamide resistance gene dfrA, qac and sul, streptavidin gene vatF and rifamycin resistance gene arr. The carriage rate ranged from 0.76% to 96.97%. Among them, 32.58% of the strains had GYRA 83 amino acid mutation, which mediated the resistance of the strains to quinolones. One severely resistant strain (PIN-YC-2019139) carried a resistance gene cluster consisting of 11 resistance genes and multiple transferring elements, suggesting that mobile elements mediate resistance transferring among Y. enterocolitica strains.

  Conclusion  From 2018 to 2021, the drug resistance of Y. enterocolitica strains isolated from Jiangsu was severe. The acquired drug resistance genes and the mutation of inherent genes led to the strains showed diverse drug insensitivity profiles. The chimerism of drug resistance genes and mobile elements was a potential risk for accelerated the transferring of drug resistance gene clusters. The results suggest that monitoring and rational use of antibiotics should be strengthened to find the emergence of super-resistant Y. enterocolitica strains.