{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T21:14:24Z","timestamp":1778274864305,"version":"3.51.4"},"reference-count":43,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T00:00:00Z","timestamp":1778198400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"MIP Pharma Croatia"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Background\/Objectives: Antimicrobial resistance is a major public health concern, particularly among multidrug-resistant (MDR) Enterobacterales. Nitroxoline is an older antibiotic with a unique mechanism of action that has not been widely used in recent decades. This study aimed to evaluate the in vitro activity of nitroxoline against Extended-Spectrum Beta-Lactamase (ESBL)-producing Escherichia coli (E. coli) and MDR Klebsiella pneumoniae (K. pneumoniae) isolated from urine samples of outpatients in Split-Dalmatia County, Croatia. Methods: Nitroxoline susceptibility was assessed using disk diffusion for E. coli (n = 26) and broth microdilution for K. pneumoniae (n = 33). Results: ESBL-producing E. coli isolates showed high susceptibility to nitroxoline, with 25 (96.2%) classified as susceptible. In contrast, K. pneumoniae isolates exhibited high minimum inhibitory concentration (MIC) values (range 16\u2013128 mg\/L; median 32 mg\/L), indicating limited activity. Conclusions: Nitroxoline demonstrated strong in vitro activity against ESBL-producing E. coli but limited activity against MDR K. pneumoniae. Interpretation of the findings for K. pneumoniae is constrained by the lack of established clinical breakpoints.<\/jats:p>","DOI":"10.3390\/antibiotics15050479","type":"journal-article","created":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T20:11:13Z","timestamp":1778271073000},"page":"479","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Contrasting In Vitro Activity of Nitroxoline Against Multidrug-Resistant Escherichia coli and Klebsiella pneumoniae Isolates from Outpatients"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-5599-4283","authenticated-orcid":false,"given":"Dominik","family":"Male\u0161","sequence":"first","affiliation":[{"name":"Teaching Institute for Public Health, Split-Dalmatia County, 21000 Split, Croatia"},{"name":"General Hospital of \u0160ibenik-Knin County, 22000 Sibenik, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zvonimir","family":"Bari\u0161i\u0107","sequence":"additional","affiliation":[{"name":"Teaching Institute for Public Health, Split-Dalmatia County, 21000 Split, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8091-6347","authenticated-orcid":false,"given":"Darko","family":"Kero","sequence":"additional","affiliation":[{"name":"Study Program of Dental Medicine, School of Medicine, University of Split, 21000 Split, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5260-6106","authenticated-orcid":false,"given":"Merica","family":"Carev","sequence":"additional","affiliation":[{"name":"Teaching Institute for Public Health, Split-Dalmatia County, 21000 Split, Croatia"},{"name":"University of Split, Faculty of Health Sciences, 21000 Split, Croatia"},{"name":"School of Medicine, University of Split, 21000 Split, Croatia"},{"name":"ESCMID Food-and-Waterborne Infections Study Group, 4051 Basel, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"E00174\u2013E20","DOI":"10.1128\/CMR.00174-20","article-title":"The Changing Face of the Family Enterobacteriaceae (Order: \u2018Enterobacterales\u2019): New Members, Taxonomic Issues, Geographic Expansion, and New Diseases and Disease Syndromes","volume":"34","author":"Janda","year":"2021","journal-title":"Clin. 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