{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T02:24:07Z","timestamp":1790303047092,"version":"4.1.0"},"reference-count":41,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,10,26]],"date-time":"2021-10-26T00:00:00Z","timestamp":1635206400000},"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. Cell. Infect. Microbiol."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>Over the last two decades, the prevalence of colistin resistance among the members of <jats:italic>Enterobacteriaceae<\/jats:italic> has been increasing, particularly among <jats:italic>Klebsiella pneumoniae<\/jats:italic> isolates; this limits the potential use of colistin and leads to worsened clinical outcomes.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We investigated the prevalence and genetic characteristics of colistin-resistant <jats:italic>K. pneumoniae<\/jats:italic> (COLR-KP) in clinical isolates using genomic sequencing.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>In total, 53 K<jats:italic>. pneumoniae<\/jats:italic> isolates (4.5%, 53\/1,171) were confirmed as COLR-KP, of which eight isolates carried mobile colistin-resistant (<jats:italic>mcr<\/jats:italic>) gene. Although the overall prevalence rate (0.7%, 8\/1,171) of <jats:italic>mcr<\/jats:italic>-like genes in clinical <jats:italic>K. pneumoniae<\/jats:italic> remained relatively low, the presence of <jats:italic>mcr<\/jats:italic> (15.1%, 8\/53) among the COLR-KP isolates indicated that the mobile resistance gene was already widespread among <jats:italic>K. pneumoniae<\/jats:italic> isolates in hospital setting. We randomly selected 13 COLR-KP isolates (four <jats:italic>mcr<\/jats:italic>-bearing and nine non-<jats:italic>mcr<\/jats:italic>-bearing isolates) for whole-genome sequencing, including two pandrug-resistant and four sequence type 11 (ST11) isolates. Phylogenetic analysis revealed that all COLR-KP isolates were genetically diverse. Among the four <jats:italic>mcr<\/jats:italic>-bearing isolates, three (KP4, KP18, and KP30) were positive for <jats:italic>mcr-1<\/jats:italic> and one (KP23) for <jats:italic>mcr-8<\/jats:italic>; none of the other <jats:italic>mcr<\/jats:italic> genes were detected. The <jats:italic>mcr-1<\/jats:italic> in the KP4 and KP30 isolates were located in an <jats:italic>IncX4<\/jats:italic> plasmid (approximately 33 kb) and could be successfully transferred to <jats:italic>Escherichia coli<\/jats:italic> J53AZ<jats:sup>R<\/jats:sup>. In contrast, for the <jats:italic>mcr-8<\/jats:italic>-bearing plasmid in KP23 (<jats:italic>IncFII<\/jats:italic>), colistin resistance could not be transferred by conjugation. The mcr-1-producing isolate KP18 coexists a novel plasmid-carried tigecycline resistance gene tmexCD1-toprJ1. The most common chromosomal mutation associated with colistin resistance was a T246A amino acid substitution in PmrB, which was identified in most COLR-KP isolates (11\/13, 84.6%). All ST11 isolates additionally had an R256G amino acid substitution. Critical virulence factors associated with hypervirulent <jats:italic>K. pneumoniae<\/jats:italic> were detected in four COLR-KP isolates; these virulence factors included aerobactin, salmochelin, and yersiniabactin.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>We found that <jats:italic>mcr<\/jats:italic>-bearing COLR-KP emerged in our hospital and was growing at an increasing rate. Simultaneous emergence of hypervirulence and colistin\u2013tigecycline\u2013carbapenem resistance in the epidemic clone ST11 <jats:italic>K. pneumoniae<\/jats:italic> was also observed; this highlights the significance of active and continuous surveillance.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fcimb.2021.673503","type":"journal-article","created":{"date-parts":[[2021,10,26]],"date-time":"2021-10-26T05:49:10Z","timestamp":1635227350000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":35,"title":["Molecular Mechanisms of Colistin Resistance in Klebsiella pneumoniae in a Tertiary Care Teaching Hospital"],"prefix":"10.3389","volume":"11","author":[{"given":"Yanling","family":"Liu","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yiqing","family":"Lin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ziwen","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Niya","family":"Hu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiong","family":"Liu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenkai","family":"Zhou","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiuzhen","family":"Li","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Longhua","family":"Hu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian","family":"Guo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaotian","family":"Huang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lingbing","family":"Zeng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2021,10,26]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"6969","DOI":"10.1128\/AAC.01456-16","article-title":"mgrB Mutations Mediating Polymyxin B Resistance in Klebsiella Pneumoniae Isolates From Rectal Surveillance Swabs in Brazil","volume":"60","author":"Aires","year":"2016","journal-title":"Antimicrob. 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