AUTHOR=Maciuca Iuliana E. , Cummins Max L. , Cozma Andreea P. , Rimbu Cristina M. , Guguianu Eleonora , Panzaru Carmen , Licker Monica , Szekely Edit , Flonta Mirela , Djordjevic Steven P. , Timofte Dorina 

TITLE=Genetic Features of mcr-1 Mediated Colistin Resistance in CMY-2-Producing Escherichia coli From Romanian Poultry

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.02267

DOI=10.3389/fmicb.2019.02267

ISSN=1664-302X

ABSTRACT=<p>Colistin is a last resort antibiotic used for the treatment of human infections associated with carbapenemase-producing Enterobacteriales. Here, we evaluated the occurrence of <italic>mcr-1</italic> and <italic>-2</italic> plasmid-mediated colistin resistance in colistin and/or carbapenem resistant human clinical Enterobacteriales and other gram-negative bacteria (<italic>n</italic> = 543) as well as third generation cephalosporin-resistant (3GCR) <italic>Escherichia coli</italic> isolates from poultry abattoir workers (<italic>n</italic> = 15) and poultry fecal samples (<italic>n</italic> = 92) collected from two geographically separate abattoirs in Romania. which revealed that <italic>mcr-1</italic> was present within four sequence types (STs): ST744 (<italic>n</italic> = 7), ST57 (<italic>n</italic> = 7), ST156 (<italic>n</italic> = 2), and ST10 (<italic>n</italic> = 1). Within STs, serotypes were conserved and, notably, all except one of the <italic>mcr-1-</italic>positive isolates were found to exhibit fluoroquinolone-resistance (FQR) associated SNPs in both <italic>gyrA</italic> and <italic>parC</italic>. While there were variations in genotypes, all isolates belonging to ST744, ST57, and ST156 were rich in resistance determinants, carrying aminoglycoside-modifying enzymes genes, sulfonamide resistance gene <italic>bla</italic><sub>TEM–</sub><sub>1</sub> as well as <italic>bla</italic><sub>CMY–</sub><sub>2</sub> AmpC β-lactamase resistance genes. They also exhibited high similarity in carriage of virulence genes; ST10, however, only carried the <italic>mcr-1</italic> gene. Whole genome sequencing (WGS) analysis also revealed that although the <italic>mcr-1</italic> gene was identified in a diverse population of <italic>E. coli</italic>, two STs (ST57 and ST744) predominated and interestingly, were found in isolates across both abattoirs providing evidence for clonal transmission. Also, two main genomic contexts of <italic>mcr-1</italic> isolates were revealed with all ST57 isolates harboring the <italic>mcr-1</italic> gene between two copies of IS<italic>Apl1</italic> (or the Tn<italic>6330</italic> transposon) whilst a common <italic>mcr-1</italic> containing scaffold, highly similar to IncX type <italic>mcr-1</italic>-bearing plasmids (pWI2-mcr, Accession number: <ext-link ext-link-type="DDBJ/EMBL/GenBank" xlink:href="LT838201" xmlns:xlink="http://www.w3.org/1999/xlink">LT838201</ext-link>), was present among <italic>mcr-1</italic> isolates of varying phylogenetic backgrounds (ST10, ST744 and ST156). The high prevalence of the <italic>mcr-1</italic> gene in poultry <italic>E. coli</italic> isolates with co-resistance to cephalosporins and quinolones, in a country where antimicrobial use in food production species is poorly regulated, is concerning and the findings from this study should lead to better surveillance of antimicrobial resistance (AMR) in food-production animals in Romania.</p>