{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T14:42:43Z","timestamp":1789569763566,"version":"build-2803163510"},"reference-count":52,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,1,7]],"date-time":"2025-01-07T00:00:00Z","timestamp":1736208000000},"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:sec><jats:title>Background<\/jats:title><jats:p>Colistin is an antibiotic used as a last resort to treat multidrug-resistant Gram-negative bacterial infections. Plasmid-mediated mobile colistin-resistant (<jats:italic>mcr<\/jats:italic>) genes in <jats:italic>Escherichia coli<\/jats:italic> (<jats:italic>E. coli<\/jats:italic>) are disseminated globally and are considered to be a major public health threat. This study aimed to determine the molecular characteristics of colistin-resistant <jats:italic>Escherichia coli<\/jats:italic> isolates in clinical settings in Pakistan.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>A total of 240 clinical <jats:italic>E. coli<\/jats:italic> strains isolated from urine and pus cultures were collected from two hospitals in Faisalabad and analyzed for phenotypic resistance to colistin by cultivation on CHROMagar plates supplemented with colistin 2 ug\/ml. Molecular characteristics of colistin-resistant isolates were analyzed using conventional PCR, whole genome sequencing, and bioinformatics analysis.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>PCR and whole genome analysis confirmed the presence of the <jats:italic>mcr-1<\/jats:italic> gene in 10 <jats:italic>E. coli<\/jats:italic> isolates. The minimum inhibitory concentration for colistin ranged from 4 ug\/ml to 32 ug\/ml. ResFinder analysis revealed the presence of multiple resistance determinants conferring co-resistance to <jats:italic>\u03b2<\/jats:italic>-lactams, aminoglycosides, trimethoprim, sulfonamides, tetracycline, quinolones, florfenicol, and macrolides. Hybrid genomic assembly indicated that <jats:italic>mcr-1<\/jats:italic> is carried on IncI2 plasmids. Plasmid replicon typing indicated that IncI2-type plasmids (<jats:italic>n<\/jats:italic>\u202f=\u202f10) were the most prevalent plasmids in these strains, followed by IncFIB (<jats:italic>n<\/jats:italic>\u202f=\u202f8), IncFIC (<jats:italic>n<\/jats:italic>\u202f=\u202f7), IncFIA (<jats:italic>n<\/jats:italic>\u202f=\u202f6), IncFII (4), IncQ1 (<jats:italic>n<\/jats:italic> =\u202f3), IncI1 (<jats:italic>n<\/jats:italic>\u202f=\u202f1), IncY (<jats:italic>n<\/jats:italic>\u202f=\u202f1), and IncN (<jats:italic>n<\/jats:italic>\u202f=\u202f1). The Achtman MLST typing scheme revealed a large diversity of STs among the <jats:italic>mcr-1<\/jats:italic>-positive <jats:italic>E. coli<\/jats:italic>. VirulenceFinder analysis revealed the presence of numerous virulence factors ranging from 4 to 19.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Our study revealed the emergence and dissemination of colistin-resistant <jats:italic>E. coli<\/jats:italic> isolates carrying <jats:italic>mcr-1<\/jats:italic> in hospital settings, posing a potential risk to anti-infective therapy. More efforts should be taken to monitor the prevalence of <jats:italic>mcr-1<\/jats:italic>-carrying bacteria in Pakistan.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fmicb.2024.1502528","type":"journal-article","created":{"date-parts":[[2025,1,7]],"date-time":"2025-01-07T07:05:49Z","timestamp":1736233549000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":10,"title":["Dissemination of clinical Escherichia coli harboring the mcr-1 gene in Pakistan"],"prefix":"10.3389","volume":"15","author":[{"given":"Sabahat","family":"Abdullah","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Muhammad Ahmad","family":"Mushtaq","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kalim","family":"Ullah","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brekhna","family":"Hassan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariya","family":"Azam","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Muhammad Asif","family":"Zahoor","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juan","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianzhen","family":"Xu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mark A.","family":"Toleman","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mashkoor","family":"Mohsin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,1,7]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"e00584","DOI":"10.1128\/spectrum.00113-24","article-title":"Whole genome-based genetic insights of Bla NDM producing clinical E. coli isolates in hospital settings of Pakistant","volume":"11","author":"Abdullah","year":"2023","journal-title":"Microbiol Spectrum"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"965","DOI":"10.2147\/IDR.S199844","article-title":"Molecular mechanisms related to colistin resistance in Enterobacteriaceae","volume":"12","author":"Aghapour","year":"2019","journal-title":"Infect. 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