Acquired resistome and plasmid sequencing of mcr-1 carrying multi-drug resistant Enterobacterales from poultry and their potential transmissibility to humans

Purpose To investigate the acquired resistome in 18 colistin resistant Escherichia coli isolated from different poultry farms in Lebanon, analyze Inc plasmids associated with mcr, and assess potential transmission to humans. Methods & Materials A total of 18 E. coli were recovered from poultry feces collected from poultry farms in Lebanon. BMD assay was performed to determine the antimicrobial resistance profiles. Whole-genome sequencing highlighted genetic resistance determinants. Transformation confirmed transmissibility of mcr. Results BMD results showed that all the 18 isolates were colistin resistant. Transformation confirmed that the plasmids carrying mcr-1 were transmissible. Sequencing showed that ST1140 was the most prevalent. The most frequent resistance determinants were tetA and floR. A total of 15 different plasmid replicon types were identified. The mcr-1 was predominantly located on IncX4 plasmids. Additionally, two isolates harbored the IncI2-type self-conjugative and IncI2-type mcr-1-harboring plasmids respectively. Conclusion The findings show that mcr was the most prevalent resistance determinant in multi-drug resistant E. coli isolated poultry farms in Lebanon. The occurrence of mcr on mobile plasmids highlights a risk of transmission to humans.