@article{mbs:/content/journal/mgen/10.1099/mgen.0.000365, author = "Alba, Patricia and Leekitcharoenphon, Pimlapas and Carfora, Virginia and Amoruso, Roberta and Cordaro, Gessica and Di Matteo, Paola and Ianzano, Angela and Iurescia, Manuela and Diaconu, Elena L. and Study Group, ENGAGE-EURL-AR Network and Pedersen, Susanne K. and Guerra, Beatriz and Hendriksen, Rene S. and Franco, Alessia and Battisti, Antonio", title = "Molecular epidemiology of Salmonella Infantis in Europe: insights into the success of the bacterial host and its parasitic pESI-like megaplasmid", journal= "Microbial Genomics", year = "2020", volume = "6", number = "5", pages = "", doi = "https://doi.org/10.1099/mgen.0.000365", url = "https://www.microbiologyresearch.org/content/journal/mgen/10.1099/mgen.0.000365", publisher = "Microbiology Society", issn = "2057-5858", type = "Journal Article", keywords = "multidrug resistance", keywords = "pESI-like", keywords = "megaplasmids", keywords = "whole genome sequencing", keywords = "Salmonella Infantis", keywords = "ESBL (Extended Spectrum Beta-Lactamases)", eid = "e000365", abstract = " Salmonella Infantis is one of the five serovars most frequently causing human salmonellosis in Europe, mainly associated with poultry. A clone harbouring a conjugative plasmid of emerging S. Infantis (pESI)-like megaplasmid, carrying multidrug resistant (MDR) and extended-spectrum beta-lactamases (ESBL) genes, has spread in the Italian broiler chicken industry also causing human illness. This work is aimed at elucidating the molecular epidemiology of S. Infantis and pESI-like in Europe using whole-genome sequencing and bioinformatics analysis, and to investigate the genetic relatedness of S. Infantis clones and pESI-like from animals, meat, feed and humans provided by institutions of nine European countries. Two genotyping approaches were used: chromosome or plasmid SNP-based analysis and the minimum spanning tree (MST) algorithm based on core-genome multilocus sequence typing (cgMLST). The European S. Infantis population appeared heterogeneous, with different genetic clusters defined at core-genome level. However, pESI-like variants present in 64.1 % of the isolates were more genetically homogeneous and capable of infecting different clonal lineages in most of the countries. Two different pESI-like with ESBL genes (n=82) were observed: bla CTX-M-1-positive in European isolates and bla CTX-M-65-positive in American isolates (study outgroup). Both variants had toxin-antitoxin systems, resistance genes towards tetracyclines, trimethoprim, sulphonamides and aminoglycosides, heavy metals (merA) and disinfectants (qacEΔ). Worryingly, 66 % of the total isolates studied presented different gyrA chromosomal point mutations associated with (fluoro)quinolone resistance (MIC range 0.125–0.5 mg/L), while 18 % displayed transferable macrolide resistance mediated by mph, mef and erm(B) genes. Proper intervention strategies are needed to prevent further dissemination/transmission of MDR S. Infantis and pESI-like along the food chain in Europe.", }