AUTHOR=Barbieri Nicolle Lima , Pimenta Ramon Loureiro , de Melo Dayanne Araujo , Nolan Lisa K. , de Souza Miliane Moreira Soares , Logue Catherine M. 

TITLE=mcr-1 Identified in Fecal Escherichia coli and Avian Pathogenic E. coli (APEC) From Brazil

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.659613

DOI=10.3389/fmicb.2021.659613

ISSN=1664-302X

ABSTRACT=<p>Colisitin-associated resistance in bacteria of food producing animals has gained significant attention with the <italic>mcr</italic> gene being linked with resistance. Recently, newer variants of <italic>mcr</italic> have emerged with more than nine variants currently recognized. Reports of <italic>mcr</italic> associated resistance in <italic>Escherichia coli</italic> of poultry appear to be relatively limited, but its prevalence requires assessment since poultry is one of the most important and cheapest sources of the world’s protein and the emergence of resistance could limit our ability to treat disease outbreaks. Here, 107 <italic>E. coli</italic> isolates from production poultry were screened for the presence of <italic>mcr 1–9</italic>. The isolates were collected between April 2015 and June 2016 from broiler chickens and free-range layer hens in Rio de Janeiro, Brazil. All isolates were recovered from the trachea and cloaca of healthy birds and an additional two isolates were recovered from sick birds diagnosed with colibacillosis. All isolates were screened for the presence of <italic>mcr-1</italic> to <italic>9</italic> using PCR and Sanger sequencing for confirmation of positive genes. Additionally, pulse field gel electrophoresis (PFGE) analysis, avian fecal <italic>E. coli</italic> (APEC) virulence associated gene screening, plasmid replicon typing and antimicrobial resistance phenotype and resistance gene screening, were also carried out to further characterize these isolates. The <italic>mcr-1</italic> gene was detected in 62 (57.9%) isolates (61 healthy and 1 APEC) and the <italic>mcr-5</italic> gene was detected in 3 (2.8%) isolates; <italic>mcr-2, mcr-3, mcr-4, mcr-6, mcr-7, mcr-8</italic>, and <italic>mcr-9</italic> were not detected in any isolate. In addition, <italic>mcr 1</italic> and <italic>5</italic> positive isolates were phenotypically resistant to colistin using the agar dilution assay (&gt; 8ug/ml). PFGE analysis found that most of the isolates screened had unique fingerprints suggesting that the emergence of colistin resistance was not the result of clonal dissemination. Plasmid replicon types <italic>IncI2, FIB</italic>, <italic>and B/O</italic> were found in 38, 36, and 34% of the <italic>mcr</italic> positive isolates and were the most prevalent replicon types detected; <italic>tetA</italic> and <italic>tetB</italic> (32 and 26%, respectively) were the most prevalent antimicrobial resistance genes detected and <italic>iutA</italic>, was the most prevalent APEC virulence associated gene, detected in 50% of the isolates. Approximately 32% of the isolates examined could be classified as APEC-like, based on the presence of 3 or more genes of APEC virulence associated path panel (<italic>iroN, ompT, hlyF, iss, iutA</italic>). This study has identified a high prevalence of <italic>mcr-1</italic> in poultry isolates in Brazil, suggesting that animal husbandry practices could result in a potential source of resistance to the human food chain in countries where application of colistin in animal health is practiced. Emergence of the <italic>mcr</italic> gene and associated colisitin resistance in production poultry warrants continued monitoring from the animal health and human health perspective.</p>