Transferable r plasmids in Escherichia coli isolated from meat ducks

Abstract

This study aimed to describe the AMR characteristics and transferable R plasmids in Escherichia coli isolated from meat ducks reared in an open house system. One hundred seventy-seven (n=177) commensal E. coli were previously isolated from duck cloacal swabs. In this study, all were biochemically confirmed and examined for their susceptibilities to 15 antimicrobial agents by broth microdilution method. Transfer of R plasmids was tested by biparental mating method followed by plasmid replicon typing (PBRT) and plasmid multi-locus sequence typing (pMLST). The highest resistance rates were observed for ampicillin (83.0%) and tetracycline (81.9%) while multidrug resistance was common (86.4%). Extended-spectrum beta-lactamases (ESBLs) production were confirmed in nine isolates. R plasmids were conjugally transferred using only tetracycline (n=4), only ampicillin (n=3), only chloramphenicol (n=3) and ampicillin/tetracycline (n=3) as selective pressure. Five replicon types were identified, of which IncFrepB was most common (38.4%) in donors (n=13) and (31.2%) in transconjugants (n=16). Subtyping F type plasmids using replicon sequence typing (RST) scheme (n=6) revealed five distinct replicons combinations, including F47:A-:B- (n=2), F29:A-:B23 (n=1), F29:A-:B- (n=1), F18:A-:B- (n=1) and F4:A-:B- (n=1). AMR phenotypes were found to have a significant statistically positive correlation (p<0.05). In particular, chloramphenicol resistance was highly correlated with other AMR phenotypes. In conclusion, the high resistance rates to clinically important antimicrobial agents in this study highlight the important role of meat ducks raised in open house farming system in the dissemination of AMR bacteria that are potentially hazardous to human and environment. This confirms AMR as one health issue and routine monitoring and surveillance of AMR among bacteria from meat ducks is suggested.