Analysis of mobile genetic elements carrying mcr genes in clinical Leclercia spp. isolates

Analysis of mobile genetic elements carrying mcr genes in clinical Leclercia spp. isolates | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Analysis of mobile genetic elements carrying mcr genes in clinical Leclercia spp. isolates Dayong Chen, Ting Xie, Minghui Liu, Dongsheng Zhou, Hongning Wang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7638274/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 27 Feb, 2026 Read the published version in BMC Microbiology → Version 1 posted 11 You are reading this latest preprint version Abstract Background Leclercia adecarboxylata is an emerging clinical pathogen within the Enterobacteriaceae family and causes infections in immunocompromised and immunocompetent patients. It often demonstrates resistance to broad-spectrum β-lactams and colistin, a last-resort antibiotic against multidrug-resistant gram-negative bacteria. The global spread of mcr genes poses a serious public health concern. This study aimed to examine the prevalence and genetic contexts of mcr genes in clinical Leclercia spp. isolates from China. Results This study identified three mobile colistin resistance genes, namely, mcr-9.1 , mcr-9.2 , and a novel variant mcr-11.1 , among 11 clinical Leclercia isolates. Some of these isolates were assigned to two novel species: Leclercia sp. LecN1 and Leclercia sp. LecN2. mcr-11.1 showed the highest sequence similarity to mcr-9.1 and was located within two novel chromosomal integrative mobile elements (IMEs): Tn 6572 and Tn 6573 . mcr-9.1 was carried by a chromosomally located Tn 7 -family/Tn 6230 -subfamily transposon (Tn 6574 ) and by three IncHI2 plasmids: p707804-mcr, p1106151-mcr, and pJ807-mcr. Meanwhile, mcr-9.2 was identified in plasmid pP10164-2. These mcr genes showed diverse local genetic contexts, including mcr-11.1 – wbuC – qseCB in Tn 6573- family IMEs as well as IS 903B – mcr-9.1 – wbuC – qseCB – exeA – int –IS 26 and its variants within the Tn 6230 -related regions of Tn 6574 and IncHI2 plasmids. Tn 1696 -related regions carried numerous mobile genetic elements (MGEs), further facilitating the dissemination of various antibiotic resistance genes (ARGs). Conclusions This study has identified mcr-11.1 , a novel gene, and many novel chromosomal MGEs (Tn 6572 –Tn 6574 ) in clinical Leclercia spp. isolates, including two new putative species. Along with four identified plasmids, these chromosomal MGEs demonstrated diverse mcr genetic contexts and suggested great potentials for the dissemination of ARGs. This study highlighted a concerning mechanism for mcr gene transmission and indicates the urgent need for ongoing resistance surveillance. colistion lactum ARG plasmid Leclercia Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementaryFile.zip Tables.docx Cite Share Download PDF Status: Published Journal Publication published 27 Feb, 2026 Read the published version in BMC Microbiology → Version 1 posted Editorial decision: Revision requested 01 Dec, 2025 Reviews received at journal 28 Nov, 2025 Reviewers agreed at journal 19 Nov, 2025 Reviewers agreed at journal 18 Nov, 2025 Reviews received at journal 11 Nov, 2025 Reviewers agreed at journal 26 Oct, 2025 Reviewers invited by journal 21 Oct, 2025 Editor assigned by journal 21 Oct, 2025 Editor invited by journal 17 Oct, 2025 Submission checks completed at journal 17 Oct, 2025 First submitted to journal 10 Oct, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7638274","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":538586411,"identity":"2087ab39-1a49-4fe9-9ae4-fbb303a9de72","order_by":0,"name":"Dayong Chen","email":"","orcid":"","institution":"Sichuan University","correspondingAuthor":false,"prefix":"","firstName":"Dayong","middleName":"","lastName":"Chen","suffix":""},{"id":538586412,"identity":"78f09ac7-3125-4306-9fac-b9637d49c75d","order_by":1,"name":"Ting Xie","email":"","orcid":"","institution":"Academy of Military Medical 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isolates","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-microbiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mcro","sideBox":"Learn more about [BMC Microbiology](http://bmcmicrobiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/mcro","title":"BMC Microbiology","twitterHandle":"#bmcmicrobiology","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"colistion, lactum, ARG, plasmid, Leclercia","lastPublishedDoi":"10.21203/rs.3.rs-7638274/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7638274/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003e\u003cem\u003eLeclercia adecarboxylata\u003c/em\u003e is an emerging clinical pathogen within the Enterobacteriaceae family and causes infections in immunocompromised and immunocompetent patients. It often demonstrates resistance to broad-spectrum β-lactams and colistin, a last-resort antibiotic against multidrug-resistant gram-negative bacteria. The global spread of \u003cem\u003emcr\u003c/em\u003e genes poses a serious public health concern. This study aimed to examine the prevalence and genetic contexts of \u003cem\u003emcr\u003c/em\u003e genes in clinical \u003cem\u003eLeclercia\u003c/em\u003e spp. isolates from China.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThis study identified three mobile colistin resistance genes, namely, \u003cem\u003emcr-9.1\u003c/em\u003e, \u003cem\u003emcr-9.2\u003c/em\u003e, and a novel variant \u003cem\u003emcr-11.1\u003c/em\u003e, among 11 clinical \u003cem\u003eLeclercia\u003c/em\u003e isolates. Some of these isolates were assigned to two novel species: \u003cem\u003eLeclercia\u003c/em\u003e sp. LecN1 and \u003cem\u003eLeclercia\u003c/em\u003e sp. LecN2. \u003cem\u003emcr-11.1\u003c/em\u003e showed the highest sequence similarity to \u003cem\u003emcr-9.1\u003c/em\u003e and was located within two novel chromosomal integrative mobile elements (IMEs): Tn\u003cem\u003e6572\u003c/em\u003e and Tn\u003cem\u003e6573\u003c/em\u003e. \u003cem\u003emcr-9.1\u003c/em\u003e was carried by a chromosomally located Tn\u003cem\u003e7\u003c/em\u003e-family/Tn\u003cem\u003e6230\u003c/em\u003e-subfamily transposon (Tn\u003cem\u003e6574\u003c/em\u003e) and by three IncHI2 plasmids: p707804-mcr, p1106151-mcr, and pJ807-mcr. Meanwhile, \u003cem\u003emcr-9.2\u003c/em\u003e was identified in plasmid pP10164-2. These \u003cem\u003emcr\u003c/em\u003e genes showed diverse local genetic contexts, including \u003cem\u003emcr-11.1\u003c/em\u003e\u0026ndash;\u003cem\u003ewbuC\u003c/em\u003e\u0026ndash;\u003cem\u003eqseCB\u003c/em\u003e in Tn\u003cem\u003e6573-\u003c/em\u003efamily IMEs as well as IS\u003cem\u003e903B\u003c/em\u003e\u0026ndash;\u003cem\u003emcr-9.1\u003c/em\u003e\u0026ndash;\u003cem\u003ewbuC\u003c/em\u003e\u0026ndash;\u003cem\u003eqseCB\u003c/em\u003e\u0026ndash;\u003cem\u003eexeA\u003c/em\u003e\u0026ndash;\u003cem\u003eint\u003c/em\u003e\u0026ndash;IS\u003cem\u003e26\u003c/em\u003e and its variants within the Tn\u003cem\u003e6230\u003c/em\u003e-related regions of Tn\u003cem\u003e6574\u003c/em\u003e and IncHI2 plasmids. Tn\u003cem\u003e1696\u003c/em\u003e-related regions carried numerous mobile genetic elements (MGEs), further facilitating the dissemination of various antibiotic resistance genes (ARGs).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eThis study has identified \u003cem\u003emcr-11.1\u003c/em\u003e, a novel gene, and many novel chromosomal MGEs (Tn\u003cem\u003e6572\u003c/em\u003e\u0026ndash;Tn\u003cem\u003e6574\u003c/em\u003e) in clinical \u003cem\u003eLeclercia\u003c/em\u003e spp. isolates, including two new putative species. Along with four identified plasmids, these chromosomal MGEs demonstrated diverse \u003cem\u003emcr\u003c/em\u003e genetic contexts and suggested great potentials for the dissemination of ARGs. This study highlighted a concerning mechanism for \u003cem\u003emcr\u003c/em\u003e gene transmission and indicates the urgent need for ongoing resistance surveillance.\u003c/p\u003e","manuscriptTitle":"Analysis of mobile genetic elements carrying mcr genes in clinical Leclercia spp. isolates","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-03 15:56:22","doi":"10.21203/rs.3.rs-7638274/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-01T07:21:14+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-28T14:12:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"274479335124820038573687996688386629630","date":"2025-11-19T08:59:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"233459997683829687642158164867839531493","date":"2025-11-18T13:27:52+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-11T08:53:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"143580563125232648573917943659904836610","date":"2025-10-27T01:26:37+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-22T01:03:30+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-21T07:32:31+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-10-17T17:53:36+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-17T11:43:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Microbiology","date":"2025-10-10T13:55:45+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-microbiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mcro","sideBox":"Learn more about [BMC Microbiology](http://bmcmicrobiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/mcro","title":"BMC Microbiology","twitterHandle":"#bmcmicrobiology","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ee2442c7-1b0d-4070-8e48-73dd8dc102ab","owner":[],"postedDate":"November 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-02T16:00:40+00:00","versionOfRecord":{"articleIdentity":"rs-7638274","link":"https://doi.org/10.1186/s12866-026-04835-w","journal":{"identity":"bmc-microbiology","isVorOnly":false,"title":"BMC Microbiology"},"publishedOn":"2026-02-27 15:57:32","publishedOnDateReadable":"February 27th, 2026"},"versionCreatedAt":"2025-11-03 15:56:22","video":"","vorDoi":"10.1186/s12866-026-04835-w","vorDoiUrl":"https://doi.org/10.1186/s12866-026-04835-w","workflowStages":[]},"version":"v1","identity":"rs-7638274","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7638274","identity":"rs-7638274","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}