Kieffer, Nicolas Aires-de-Sousa, Marta Nordmann, Patrice Poirel, Laurent 2017 The mcr-1 (mobile colistin resistance 1) gene, which encodes phosphoethanolamine transferase, has been recently identified as a source of acquired resistance to polymyxins in Escherichia coli. Using the SuperPolymyxin selective medium, we prospectively screened 100 pigs at 2 farms in Portugal for polymyxin-resistant Enterobacteriaceae and recovered 98 plasmid-mediated MCR-1–producing isolates. Most isolates corresponded to nonclonally related E. coli belonging to many sequence types; we also found 2 Klebsiella pneumoniae sequence types. The mcr-1 gene was carried on IncHI2 or IncP plasmid backbones. Our finding of a high rate of MCR-1 producers on 2 pig farms in Portugal highlights the diffusion of that colistin-resistance determinant at the farm level. The fact that the pigs received colistin as metaphylaxis in their feed during the 6 weeks before sampling suggests selective pressure. application/pdf https://folia.unifr.ch/global/documents/306219 https://folia.unifr.ch/documents/306219/files/nor_hrm.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.3201/eid2312.170883 info:eu-repo/semantics/openAccess License undefined Emerging Infectious Diseases. - 2017, vol. 23, no. 12, p. 2023–2029 info:eu-repo/classification/udc/57 High Rate of MCR-1–Producing Escherichia coli and Klebsiella pneumoniae among Pigs, Portugal http://purl.org/coar/resource_type/c_6501