AUTHOR=Carfora Virginia , Alba Patricia , Leekitcharoenphon Pimlapas , Ballarò Daniele , Cordaro Gessica , Di Matteo Paola , Donati Valentina , Ianzano Angela , Iurescia Manuela , Stravino Fiorentino , Tagliaferri Tania , Battisti Antonio , Franco Alessia 

TITLE=Colistin Resistance Mediated by mcr-1 in ESBL-Producing, Multidrug Resistant Salmonella Infantis in Broiler Chicken Industry, Italy (2016–2017)

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01880

DOI=10.3389/fmicb.2018.01880

ISSN=1664-302X

ABSTRACT=<p>Colistin-resistance mediated by mobilisable and plasmid-borne <italic>mcr</italic> genes has emerged worldwide, threatening the efficacy of colistin, a last resort antibiotic increasingly used for treating human invasive infections by multidrug-resistant or extensively drug-resistant <italic>Enterobacteriaceae</italic>. In this study, we report the first evidence of <italic>mcr</italic>-1-mediated colistin resistance in four multidrug resistant (MDR) out of 324 <italic>Salmonella</italic> infantis from the Italian antimicrobial resistance (AMR) monitoring (2001–2017) in broilers and broiler meat. Two were also Extended Spectrum Beta-Lactamases (ESBL)-producing isolates. Characterization by whole genome sequencing (WGS), located <italic>mcr</italic>-1.1 on an incX4 plasmid. Phylogenetic analysis of these isolates with selected Italian <italic>S</italic>. Infantis previously isolated from animals, meat and human clinical cases with unknown epidemiological relationship, demonstrated that ESBL-producing, <italic>mcr</italic>-1-positive isolates belonged to the emerging pESI-like-positive-ESBL-producing clone described in Italy in 2015.</p>