{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T16:27:05Z","timestamp":1787934425568,"version":"build-2784847793"},"reference-count":44,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,7,16]],"date-time":"2021-07-16T00:00:00Z","timestamp":1626393600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:p>\n                    A collection of 177 genomes of\n                    <jats:italic>Salmonella<\/jats:italic>\n                    Typhimurium and its monophasic variant isolated in 2014\u20132019 from Italian poultry\/livestock (\n                    <jats:italic>n<\/jats:italic>\n                    = 165) and foodstuff (\n                    <jats:italic>n<\/jats:italic>\n                    = 12), previously screened for antimicrobial susceptibility and assigned to ST34 and single-locus variants, were studied in-depth to check the presence of the novel\n                    <jats:italic>mcr-9<\/jats:italic>\n                    gene and to investigate their genetic relatedness by whole genome sequencing (WGS). The study of accessory resistance genes revealed the presence of\n                    <jats:italic>mcr<\/jats:italic>\n                    -9.1 in 11 ST34 isolates, displaying elevated colistin minimum inhibitory concentration values up to 2 mg\/L and also a multidrug-resistant (MDR) profile toward up to seven antimicrobial classes. Five of them were also extended-spectrum beta-lactamases producers (\n                    <jats:italic>bla<\/jats:italic>\n                    <jats:sub>\n                      <jats:italic>SHV<\/jats:italic>\n                    <\/jats:sub>\n                    <jats:sub>\u2013<\/jats:sub>\n                    <jats:sub>12<\/jats:sub>\n                    type), mediated by the corresponding antimicrobial resistance (AMR) accessory genes. All\n                    <jats:italic>mcr<\/jats:italic>\n                    -9-positive isolates harbored IncHI2-ST1 plasmids. From the results of the Mash analysis performed on all 177 genomes, the 11\n                    <jats:italic>mcr-9<\/jats:italic>\n                    -positive isolates fell together in the same subcluster and were all closely related. This subcluster included also two\n                    <jats:italic>mcr<\/jats:italic>\n                    -9-negative isolates, and other eight\n                    <jats:italic>mcr<\/jats:italic>\n                    -9-negative ST34 isolates were present within the same parental branch. All the 21 isolates within this branch presented an IncHI2\/2A plasmid and a similar MDR gene pattern. In three representative\n                    <jats:italic>mcr<\/jats:italic>\n                    -9-positive isolates,\n                    <jats:italic>mcr-9<\/jats:italic>\n                    was demonstrated to be located on different IncHI2\/IncHI2A large-size (\u223c277\u2013297 kb) plasmids, using a combined Illumina\u2013Oxford Nanopore WGS approach. These plasmids were also compared by BLAST analysis with publicly available IncHI2 plasmid sequences harboring\n                    <jats:italic>mcr<\/jats:italic>\n                    -9. In our plasmids,\n                    <jats:italic>mcr<\/jats:italic>\n                    -9 was located in a \u223c30-kb region lacking different genetic elements of the typical core structure of\n                    <jats:italic>mcr<\/jats:italic>\n                    -9 cassettes. In this region were also identified different genes involved in heavy metal metabolism. Our results underline how genomics and WGS-based surveillance are increasingly indispensable to achieve better insights into the genetic environment and features of plasmid-mediated AMR, as in the case of such IncHI2 plasmids harboring other MDR genes beside\n                    <jats:italic>mcr<\/jats:italic>\n                    -9, that can be transferred horizontally also to other major\n                    <jats:italic>Salmonella<\/jats:italic>\n                    serovars spreading along the food chain.\n                  <\/jats:p>","DOI":"10.3389\/fmicb.2021.705230","type":"journal-article","created":{"date-parts":[[2021,7,16]],"date-time":"2021-07-16T07:29:06Z","timestamp":1626420546000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":30,"title":["Emergence of IncHI2 Plasmids With Mobilized Colistin Resistance (mcr)-9 Gene in ESBL-Producing, Multidrug-Resistant Salmonella Typhimurium and Its Monophasic Variant ST34 From Food-Producing Animals in Italy"],"prefix":"10.3389","volume":"12","author":[{"given":"Elena Lavinia","family":"Diaconu","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patricia","family":"Alba","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fabiola","family":"Feltrin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paola","family":"Di Matteo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manuela","family":"Iurescia","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eleonora","family":"Chelli","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Valentina","family":"Donati","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ilaria","family":"Marani","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Angelo","family":"Giacomi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alessia","family":"Franco","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Virginia","family":"Carfora","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2021,7,16]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1099\/mgen.0.000365","article-title":"Molecular epidemiology of Salmonella infantis in Europe: insights into the success of the bacterial host and its parasitic pESI-like megaplasmid.","volume":"6","author":"Alba","year":"2020","journal-title":"Microb. 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