Abundance of colistin-resistant Escherichia coli harbouring mcr-1 and extended-spectrum β-lactamase-producing E. coli co-harbouring blaCTX-M-55 or -65 with blaTEM isolates from chicken meat in Vietnam

Although the spread of plasmid-mediated antibiotic-resistant bacteria is a public health concern, food contamination with plasmid-mediated antibiotic-resistant Escherichia coli in Vietnam has not been well investigated. This study aimed to describe the prevalence of colistin-resistant, carbapenem-resistant, and endemic bla(CTX-M) in extended-spectrum beta-lactamase (ESBL) producing E. coli isolates. Colistin and carbapenem-resistant ESBL-producing E. coli were isolated from chickens in Vietnam and Japan. Colistin-resistant and AmpC/ESBL-producing E. coli (52% and 93%, respectively) were detected in chickens from Vietnam, in comparison to 52.7%, AmpC/ESBL-producing E. coli found in chicken from Japan. Carbapenem-resistant E. coli has not been isolated in Vietnam and Japan. Genotyping revealed that colistin-resistant E. coli harboured mcr-1, and most of the AmpC/ESBL-related genes were bla(CTX-M-55) and bla(CTX-M-65) together with bla(TEM) in Vietnamese chickens and bla(CMY-2) in Japanese chickens. Multi-drug resistance analysis showed that ESBL-producing E. coli isolates had greater resistance to quinolones, streptomycin, and chloramphenicol than colistin-resistant E. coli isolates from Vietnam, suggesting the selection of multiple antibiotic resistance genes in ESBL-producing E. coli. In conclusion, colistin-resistant E. coli was detected in approximately half of the chicken samples, the majority of which harboured mcr-1. The high prevalence of ESBL-producing E. coli has remained constant in the last 5 years. The predominant bla(CTX-M) in ESBL-producing E. coli was bla(CTX-M-55) or bla(CTX-M-65), with the coexistence of bla(TEM) in Vietnam. These results can be implemented in monitoring systems to overcome the development of antimicrobial resistance.

Automated summary

This study investigated the prevalence of antibiotic-resistant Escherichia coli in chicken meat from Vietnam and Japan. The results showed that colistin-resistant E. coli was found in approximately half of the chicken samples in Vietnam, with most of them harboring the mcr-1 gene. The prevalence of ESBL-producing E. coli remained constant in the past five years, with bla(CTX-M-55) or bla(CTX-M-65) being the predominant ESBL-related genes in Vietnam.