{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:55:20Z","timestamp":1787028920398,"version":"build-2736575974"},"reference-count":34,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2022,12,20]],"date-time":"2022-12-20T00:00:00Z","timestamp":1671494400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the RISAM scholarship from Munster Technological University","award":["RISAM_SW_2018"],"award-info":[{"award-number":["RISAM_SW_2018"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medical Sciences"],"abstract":"<jats:p>The purpose of this study was to determine the effect of sublethal concentrations of nitrofurantoin, ciprofloxacin, and trimethoprim on biofilm formation in 57 uropathogenic Escherichia coli strains (UPEC). The minimum inhibitory concentration of nitrofurantoin, ciprofloxacin, and trimethoprim was determined and the biofilm formation for each isolate with and without sub-lethal concentrations of each antibiotic was then quantified. The statistical significance of changes in biofilm formation was ascertained by way of a Dunnett\u2019s test. A total of 22.8% of strains were induced to form stronger biofilms by nitrofurantoin, 12% by ciprofloxacin, and 19% by trimethoprim; conversely 36.8% of strains had inhibited biofilm formation with nitrofurantoin, 52.6% with ciprofloxacin, and 38.5% with trimethoprim. A key finding was that even in cases where the isolate was resistant to an antibiotic as defined by EUCAST, many were induced to form a stronger biofilm when grown with sub-MIC concentrations of antibiotics, especially trimethoprim, where six of the 22 trimethoprim resistant strains were induced to form stronger biofilms. These findings suggest that the use of empirical treatment with trimethoprim without first establishing susceptibility may in fact potentiate infection in cases where a patient who is suffering from a urinary tract infection (UTI) caused by trimethoprim resistant UPEC is administered trimethoprim. This emphasizes the need for laboratory-guided treatment of UTI.<\/jats:p>","DOI":"10.3390\/medsci11010001","type":"journal-article","created":{"date-parts":[[2022,12,21]],"date-time":"2022-12-21T01:32:53Z","timestamp":1671586373000},"page":"1","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Effect of Sub-Inhibitory Concentrations of Nitrofurantoin, Ciprofloxacin, and Trimethoprim on In Vitro Biofilm Formation in Uropathogenic Escherichia coli (UPEC)"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6991-5167","authenticated-orcid":false,"given":"Shane","family":"Whelan","sequence":"first","affiliation":[{"name":"Department of Biological Sciences, Munster Technological University, Bishopstown, T12 P928 Cork, Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mary Claire","family":"O\u2019Grady","sequence":"additional","affiliation":[{"name":"Department of Clinical Microbiology, Cork University Hospital, Wilton, T12 DC4A2 Cork, Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gerard Daniel","family":"Corcoran","sequence":"additional","affiliation":[{"name":"Department of Clinical Microbiology, Cork University Hospital, Wilton, T12 DC4A2 Cork, Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5631-9710","authenticated-orcid":false,"given":"Karen","family":"Finn","sequence":"additional","affiliation":[{"name":"Department of Analytical, Biopharmaceutical and Medical Sciences, Atlantic Technological University, ATU Galway City, Dublin Road, H91 T8NW Galway, Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0872-202X","authenticated-orcid":false,"given":"Brigid","family":"Lucey","sequence":"additional","affiliation":[{"name":"Department of Biological Sciences, Munster Technological University, Bishopstown, T12 P928 Cork, Ireland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1097\/QCO.0000000000000228","article-title":"Global Epidemiology of Urinary Tract Infections","volume":"29","author":"Tandogdu","year":"2016","journal-title":"Curr. 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