{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T13:45:50Z","timestamp":1768830350973,"version":"3.49.0"},"reference-count":63,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2022,10,5]],"date-time":"2022-10-05T00:00:00Z","timestamp":1664928000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Faculty of Pharmacy of the University of Coimbra","award":["UID\/NEU\/04539\/2013"],"award-info":[{"award-number":["UID\/NEU\/04539\/2013"]}]},{"name":"FEDER funds","award":["UID\/NEU\/04539\/2013"],"award-info":[{"award-number":["UID\/NEU\/04539\/2013"]}]},{"DOI":"10.13039\/501100001871","name":"National Funds","doi-asserted-by":"publisher","award":["UID\/NEU\/04539\/2013"],"award-info":[{"award-number":["UID\/NEU\/04539\/2013"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Colistin is classified as a high-priority critical antimicrobial by the World Health Organization (WHO). A better understanding of the biological cost imposed by mcr-plasmids is paramount to comprehending their spread and may facilitate the decision about the ban of colistin in livestock. This study aimed to assess the prevalence of mcr and ESBL genes from 98 Escherichia coli and 142 Salmonella enterica isolates from food-producing animals and the impact of the mcr-1 acquisition on bacterial fitness. Only mcr-1 was identified by multiplex PCR (mcr-1 to mcr-10) in 15.3% of E. coli. Colistin MICs ranged between 8\u201332 mg\/L. In four isolates, blaTEM-1, blaCTX-M-1, and blaCTX-M-15 co-existed with mcr-1. The IncH12, IncHI1, IncP, IncN, and IncI plasmids were transferred by conjugation to E. coli J53 at frequencies of 10\u22127 to 10\u22122 cells\/recipient. Growth kinetics assays showed that transconjugants had a significantly lower growth rate than the recipient (p &lt; 0.05), and transconjugants\u2019 average growth rate was higher in the absence than in the presence of colistin (1.66 versus 1.32 (p = 0.0003)). Serial transfer assay during 10 days demonstrated that plasmid retention ranged from complete loss to full retention. Overall, mcr-1-bearing plasmids impose a fitness cost, but the loss of plasmids is highly variable, suggesting that other factors beyond colistin pressure regulate the plasmid maintenance in a bacterial population, and colistin withdrawal will not completely lead to a decrease of mcr-1 levels.<\/jats:p>","DOI":"10.3390\/antibiotics11101356","type":"journal-article","created":{"date-parts":[[2022,10,7]],"date-time":"2022-10-07T22:47:27Z","timestamp":1665182847000},"page":"1356","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Occurrence and Biological Cost of mcr-1-Carrying Plasmids Co-harbouring Beta-Lactamase Resistance Genes in Zoonotic Pathogens from Intensive Animal Production"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4277-4365","authenticated-orcid":false,"given":"Tiago","family":"Lima","sequence":"first","affiliation":[{"name":"Faculty of Pharmacy, University of Coimbra, 3000-458 Coimbra, Portugal"},{"name":"Center for Neuroscience and Cell Biology, University Coimbra, 3004-517 Coimbra, Portugal"}]},{"given":"Dina","family":"Loureiro","sequence":"additional","affiliation":[{"name":"ALS-Controlvet, 3460-070 Tondela, Portugal"}]},{"given":"Ana","family":"Henriques","sequence":"additional","affiliation":[{"name":"ALS-Controlvet, 3460-070 Tondela, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6043-819X","authenticated-orcid":false,"given":"Fernando","family":"Ramos","sequence":"additional","affiliation":[{"name":"Faculty of Pharmacy, University of Coimbra, 3000-458 Coimbra, Portugal"},{"name":"REQUIMTE\/LAQV, R. D. Manuel II, 4051-401 Oporto, Portugal"}]},{"given":"Constan\u00e7a","family":"Pomba","sequence":"additional","affiliation":[{"name":"Centre for Interdisciplinary Research in Animal Health, Laboratory of Antibiotic Resistance, CIISA, Faculty of Veterinary Medicine, University of Lisbon, 1300-477 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8879-5113","authenticated-orcid":false,"given":"Sara","family":"Domingues","sequence":"additional","affiliation":[{"name":"Faculty of Pharmacy, University of Coimbra, 3000-458 Coimbra, Portugal"},{"name":"Center for Neuroscience and Cell Biology, University Coimbra, 3004-517 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7479-8540","authenticated-orcid":false,"given":"Gabriela Jorge","family":"da Silva","sequence":"additional","affiliation":[{"name":"Faculty of Pharmacy, University of Coimbra, 3000-458 Coimbra, Portugal"},{"name":"Center for Neuroscience and Cell Biology, University Coimbra, 3004-517 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,5]]},"reference":[{"key":"ref_1","unstructured":"WHO (2019, October 10). 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