Colistin Resistance ㏌ Enterobacteriaceae Isolated from Arthropods in Gifu City, Japan

Abstract Background The emergence of antimicrobial-resistant (AMR) bacteria is an important concern for public and livestock health. Arthropods may serve as vectors that disseminate AMR bacteria across different environments. We examined the phenotype and genotype of antimicrobial resistance in Enterobacteriaceae collected from arthropods in Gifu city, Japan. Results A total of 186 Enterobacteriaceae from 94 arthropods were obtained and tested for antimicrobial susceptibility. All isolates were susceptible to the antimicrobial agents tested, except for colistin (39 isolates) and kanamycin (one isolate). The aph(3')-Ia gene and amino acid substitutions in the two-component system were responsible for the kanamycin and colistin resistance, respectively. Conclusion Overall Enterobacteriaceae isolated from the arthropods were susceptible to most of the antimicrobial agents. However, a high prevalence of colistin resistance was observed in the isolates from the arthropods. We suspect that this was a result of the production of antimicrobial peptides by the arthropods rather than selective pressure or exposure to colistin in the environment. Thus, arthropods maybe a potential reservoir of colistin resistant bacteria. These findings could be beneficial to public and livestock health management.