Occurrence and characterization of mcr-1-harbouring Escherichia coli isolated from pigs in Great Britain from 2013 to 2015

• Published in: Journal of antimicrobial chemotherapy 2017-03, Vol.72 (3), p.691-695
• Main Authors: Duggett, Nicholas A, Sayers, Ellie, AbuOun, Manal, Ellis, Richard J, Nunez-Garcia, Javier, Randall, Luke, Horton, Robert, Rogers, Jon, Martelli, Francesca, Smith, Richard P, Brena, Camilla, Williamson, Susanna, Kirchner, Miranda, Davies, Robert, Crook, Derrick, Evans, Sarah, Teale, Chris, Anjum, Muna F
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - pharmacology; DNA Transposable Elements - genetics; Drug Resistance, Bacterial - genetics; Escherichia coli - genetics; Escherichia coli - isolation & purification; Escherichia coli Infections - epidemiology; Escherichia coli Infections - microbiology; Escherichia coli Infections - transmission; Escherichia coli Infections - veterinary; Escherichia coli Proteins - genetics; Feces - microbiology; Humans; Livestock - microbiology; Microbial Sensitivity Tests; Original Research; Plasmids; Swine; Swine Diseases - microbiology; Swine Diseases - transmission; United Kingdom - epidemiology
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkw477

To determine the occurrence of mcr-1 -harbouring Escherichia coli in archived pig material originating in Great Britain (GB) from 2013 to 2015 and characterize mcr-1 plasmids. Enrichment and selective culture of 387 archived porcine caecal contents and recovery from archive of 1109 E. coli isolates to identify colistin-resistant bacteria by testing for the presence of mcr-1 by PCR and RT-PCR. mcr-1 -harbouring E. coli were characterized by WGS and compared with other available mcr-1 WGS. Using selective isolation following enrichment, the occurrence of mcr-1 E. coli in caeca from healthy pigs at slaughter from unique farms in GB was 0.6% (95% CI 0%-1.5%) in 2015. mcr-1 E. coli were also detected in isolates from two porcine veterinary diagnostic submissions in 2015. All isolates prior to 2015 were negative. WGS analysis of the four mcr-1 -positive E. coli indicated no other antimicrobial resistance (AMR) genes were linked to mcr-1 -plasmid-bearing contigs, despite all harbouring multiple AMR genes. The sequence similarity between mcr-1 -plasmid-bearing contigs identified and those found in GB, Chinese and South African human isolates and Danish, French and Estonian livestock-associated isolates was 90%-99%. mcr-1- harbouring plasmids were diverse, implying transposable elements are involved in mcr-1 transmission in GB. The low number of mcr-1 -positive E. coli isolates identified suggested mcr-1 is currently uncommon in E. coli from pigs within GB. The high sequence similarity between mcr-1 plasmid draft genomes identified in pig E. coli and plasmids found in human and livestock-associated isolates globally requires further investigation to understand the full implications.