Diverse Escherichia coli lineages from domestic animals carrying colistin resistance gene mcr-1 in an Ecuadorian household

• Published in: Journal of global antimicrobial resistance. 2020-09, Vol.22, p.63-67
• Main Authors: Loayza-Villa, Fernanda, Salinas, Liseth, Tijet, Nathalie, Villavicencio, Fernando, Tamayo, Rafael, Salas, Stephanie, Rivera, Ruth, Villacis, Jose, Satan, Carolina, Ushiña, Liliana, Muñoz, Olga, Zurita, Jeannette, Melano, Roberto, Reyes, Jorge, Trueba, Gabriel A.
• Format: Article
• Language: English
• Subjects: Animals; Animals, Domestic - microbiology; Anti-Bacterial Agents - pharmacology; Antimicrobial resistance; Chickens - microbiology; Colistin - pharmacology; Commensal E. coli; Companion animals; Cross-Sectional Studies; Dogs - microbiology; Ecuador; Escherichia coli - genetics; Escherichia coli Proteins - genetics; Horizontal gene transfer; IncI2 plasmids; mcr-1; Microbial Sensitivity Tests; Multilocus Sequence Typing
• ISSN: 2213-7165; 2213-7173
• DOI: 10.1016/j.jgar.2019.12.002

•Domestic animals and a human carry colistin-resistant E. coli in a household.•Different E. coli clones carry mrc-1.1.•The mcr-1.1 gene was carried by a very similar IncI2 plasmid in different strains. The aim of this study was to detect potential animal reservoirs of Escherichia coli carrying the mcr-1 gene in an Ecuadorian household. The mobile colistin-resistance gene, mcr-1, was first detected in Ecuador in a commensal E. coli isolate from a boy. A cross-sectional study was performed to detect the possible source of colistin-resistant E. coli in the boy’s household. Faecal swabs and soil faecal samples were collected from companion animals. Samples were plated on selective media to isolate colistin-resistant E. coli and isolates were submitted to PCR detection of mcr-1, pulsed field gel electrophoresis (PFGE), and multi-locus sequences typing (MLST). Moreover, the genomes of all the isolates were sequenced. Three different colistin-resistant E. coli sequence types (ST3941, 1630 and 2170), corresponding to three PFGE patterns, were obtained from a chicken and two dogs; these isolates were different from the human isolate (ST609). By whole-genome sequencing, the mcr-1.1 gene was found on IncI2 plasmids with very high nucleotide identity. Our results indicate a polyclonal dissemination of mcr-1.1 in the environment surrounding the first MCR-producing E. coli strain reported in Ecuador. Our findings support the idea of lateral dissemination of mcr-1.1 gene between unrelated E. coli isolates.