A one-health sampling strategy to explore the dissemination and relationship between colistin resistance in human, animal, and environmental sectors in Laos

This study was designed to investigate the molecular epidemiology of mobile colistin resistance (mcr) using a “one-health” approach in Laos and to predict whether any dominant plasmid backbone and/or strain type influences the dissemination of mcr. We collected 673 samples from humans (rectal normal flora), poultry, and the environment (water, flies, birds, etc.) in Vientiane, Laos, from May to September 2018. A total of 238 Escherichia coli (E. coli) isolated from non-duplicative samples, consisting of 98 MCR-positive E. coli (MCRPEC) (“mcr” denotes the gene encoding mobile colistin resistance, and “MCR” denotes the subsequent protein encoded by mcr) and 140 MCR-negative E. coli (MCRNEC), were characterized by phenotype and Illumina sequencing. A subset of MCRPEC was selected for MinION sequencing, conjugation assay, plasmid stability, and growth kinetics in vitro. The prevalence of MCRPEC was found to be 14.6% (98/673), with the highest prevalence in human rectal swabs (45.9% (45/98), p