phaidra.vetmeduni.ac.at o:2412 DOI 10.1128/spectrum.01015-23 Genomic Evidence of mcr-1.26 IncX4 Plasmid Transmission between Poultry and Humans Colistin is still commonly used and misused in animal husbandry driving the evolution and dissemination of transmissible plasmid-mediated colistin resistance (mcr). mcr-1.26 is a rare variant and, so far, has only been detected in Escherichia coli obtained from a hospitalized patient in Germany in 2018. Recently, it was also notified in fecal samples from a pigeon in Lebanon. We report on the presence of 16 colistin-resistant, mcr-1.26-carrying extended-spectrum beta-lactamase (ESBL)-producing and commensal E. coli isolated from poultry samples in Germany, of which retail meat was the most common source. Short- and long-read genome sequencing and bioinformatic analyses revealed the location of mcr-1.26 exclusively on IncX4 plasmids. mcr-1.26 was identified on two different IncX4 plasmid types of 33 and 38 kb and was associated with an IS6-like element. Based on the genetic diversity of E. coli isolates, transmission of the mcr-1.26 resistance determinant is mediated by horizontal transfer of IncX4 plasmids, as confirmed by conjugation experiments. Notably, the 33-kb plasmid is highly similar to the plasmid reported for the human sample. Furthermore, we identified the acquisition of an additional beta-lactam resistance linked to a Tn2 transposon on the mcr-1.26 IncX4 plasmids of three isolates, indicating progressive plasmid evolution. Overall, all described mcr-1.26-carrying plasmids contain a highly conserved core genome necessary for colistin resistance development, transmission, replication, and maintenance. Variations in the plasmid sequences are mainly caused by the acquisition of insertion sequences and alteration in intergenic sequences or genes of unknown function. eng Animals; Humans; Colistin; Escherichia coli; Anti-Bacterial Agentspharmacology; Poultry; Escherichia coli Proteinsgenetics; Plasmidsgenetics; Genomics; Drug Resistance, Bacterialgenetics; Microbial Sensitivity Tests 2023-12-06T09:49:58.227Z LOMv1.0 Author BEGIN:VCARD VERSION:3.0 N:Binsker;Ulrike; FN:Ulrike Binsker X-ORCID:https://orcid.org/0000-0002-1963-1916 END:VCARD BEGIN:VCARD VERSION:3.0 N:Hammerl;Jens A.; FN:Jens A. Hammerl X-ORCID:https://orcid.org/0000-0002-6930-4358 END:VCARD BEGIN:VCARD VERSION:3.0 N:Käsbohrer;Annemarie; FN:Annemarie Käsbohrer X-ORCID:https://orcid.org/0000-0003-2966-2713 END:VCARD BEGIN:VCARD VERSION:3.0 N:Werner;Guido; FN:Guido Werner END:VCARD BEGIN:VCARD VERSION:3.0 N:Oelgeschläger;Kathrin; FN:Kathrin Oelgeschläger END:VCARD BEGIN:VCARD VERSION:3.0 N:Neumann;Bernd; FN:Bernd Neumann END:VCARD https://w3id.org/kim/hcrt/scheme https://w3id.org/kim/hcrt/text Textdokument Text LOMv1.0 yes https://creativecommons.org/licenses/by/4.0 application/pdf 441582 https://phaidra.vetmeduni.ac.at/o:2412 https://phaidra.vetmeduni.ac.at/api/object/o:2412/thumbnail LOMv1.0 discipline