{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T09:27:02Z","timestamp":1785403622607,"version":"3.56.0"},"reference-count":26,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T00:00:00Z","timestamp":1781654400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006345","name":"Nicolaus Copernicus University in Toru\u0144","doi-asserted-by":"crossref","award":["90-SIDUB.6102.74.2024.G4NCUS9"],"award-info":[{"award-number":["90-SIDUB.6102.74.2024.G4NCUS9"]}],"id":[{"id":"10.13039\/501100006345","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100006345","name":"Nicolaus Copernicus University in Toru\u0144","doi-asserted-by":"crossref","award":["176\/2024\/Grants4NCUStudents"],"award-info":[{"award-number":["176\/2024\/Grants4NCUStudents"]}],"id":[{"id":"10.13039\/501100006345","id-type":"DOI","asserted-by":"crossref"}]},{"award":["90-SIDUB.6102.74.2024.G4NCUS9"],"award-info":[{"award-number":["90-SIDUB.6102.74.2024.G4NCUS9"]}],"id":[{"id":"https:\/\/ror.org\/0102mm775","id-type":"ROR","asserted-by":"publisher"}]},{"award":["176\/2024\/Grants4NCUStudents"],"award-info":[{"award-number":["176\/2024\/Grants4NCUStudents"]}],"id":[{"id":"https:\/\/ror.org\/0102mm775","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Urinary tract infections (UTIs), particularly catheter-associated UTIs (CAUTIs), represent a significant clinical problem due to the predominance of Gram-negative uropathogens, their ability to form biofilms, and the increasing prevalence of antimicrobial resistance, which together reduce the effectiveness of conventional antibiotic therapy. This study aimed to evaluate the antimicrobial activity of selected natural plant-derived compounds against clinical Gram-negative uropathogens isolated from CAUTIs. The antibacterial effects of gallic acid, quercetin-3-D-glucuronide, and apigenin were assessed against Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis, including both ciprofloxacin-susceptible and -resistant strains. Antimicrobial activity was determined using the broth microdilution method, followed by quantitative assessment of bacterial viability based on colony-forming unit (CFU) enumeration. Gallic acid exhibited the strongest concentration-dependent inhibitory activity, reducing bacterial viability by up to 2\u20133 log10 CFU across all tested species. Quercetin-3-D-glucuronide demonstrated moderate antibacterial effects with a predominantly bacteriostatic profile, resulting in a partial but consistent reduction in CFU counts. In contrast, apigenin showed only weak effects on bacterial viability under the applied experimental conditions. None of the tested compounds achieved complete bacterial eradication. These findings indicate that gallic acid and quercetin-3-D-glucuronide possess inhibitory activity against Gram-negative uropathogens, including antibiotic-resistant strains, supporting their potential use as adjunctive agents targeting bacterial persistence in UTIs rather than as standalone antimicrobials. In the present study, the viability of planktonic bacterial cells was assessed; however, future studies should focus on evaluating the direct impact of the tested compounds on biofilm structure and biofilm formation dynamics.<\/jats:p>","DOI":"10.3390\/ijms27125463","type":"journal-article","created":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T08:22:56Z","timestamp":1781684576000},"page":"5463","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Evaluation of Antimicrobial Activity of Gallic Acid, Quercetin-3-D-Glucuronide, and Apigenin Against Gram-Negative Uropathogens: A Novel Approach to Urinary Tract Infection Therapy"],"prefix":"10.3390","volume":"27","author":[{"given":"Dagmara","family":"Fydrych","sequence":"first","affiliation":[{"name":"Department of Microbiology, Collegium Medicum of L. Rydygier in Bydgoszcz, Nicolaus Copernicus University in Toru\u0144, 9 M. 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Sk\u0142odowskiej-Curie Street, 85-094 Bydgoszcz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1038\/nrmicro3432","article-title":"Urinary tract infections: Epidemiology, mechanisms of infection and treatment options","volume":"13","author":"Walker","year":"2015","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1128\/CMR.15.2.167-193.2002","article-title":"Biofilms: Survival mechanisms of clinically relevant microorganisms","volume":"15","author":"Donlan","year":"2002","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"276","DOI":"10.1093\/femsre\/fux010","article-title":"Molecular mechanisms of biofilm-based antibiotic resistance and tolerance in pathogenic bacteria","volume":"41","author":"Hall","year":"2017","journal-title":"FEMS Microbiol. Rev."},{"key":"ref_4","unstructured":"World Health Organization (2015). Global Action Plan on Antimicrobial Resistance, WHO Press."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"564","DOI":"10.1128\/CMR.12.4.564","article-title":"Plant products as antimicrobial agents","volume":"12","author":"Cowan","year":"1999","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"740","DOI":"10.1038\/nrmicro.2017.99","article-title":"Targeting microbial biofilms: Current and prospective therapeutic strategies","volume":"15","author":"Koo","year":"2017","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1016\/j.ijantimicag.2005.09.002","article-title":"Antimicrobial activity of flavonoids","volume":"26","author":"Cushnie","year":"2005","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"174","DOI":"10.1016\/j.copbio.2011.08.007","article-title":"Polyphenols as antimicrobial agents","volume":"23","author":"Daglia","year":"2012","journal-title":"Curr. Opin. Biotechnol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"755","DOI":"10.1080\/08927014.2012.706751","article-title":"The activity of ferulic and gallic acids in biofilm prevention and control of pathogenic bacteria","volume":"28","author":"Borges","year":"2012","journal-title":"Biofouling"},{"key":"ref_10","first-page":"M1","article-title":"Antibacterial activity of gallic acid isolated from Galla rhois","volume":"74","author":"Choi","year":"2009","journal-title":"J. Food Sci."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Khare, T., Anand, U., Dey, A., Assaraf, Y.G., Chen, Z.-S., Liu, Z., and Kumar, V. (2021). Exploring phytochemicals for combating antibiotic resistance in microbial pathogens. Front. Pharmacol., 12.","DOI":"10.3389\/fphar.2021.720726"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1002\/ptr.6208","article-title":"Antibacterial activity of flavonoids and their structure\u2013activity relationship: An update review","volume":"33","author":"Farhadi","year":"2019","journal-title":"Phytother. Res."},{"key":"ref_13","first-page":"3326","article-title":"A structure\u2013activity relationship study of flavonoids as inhibitors of Escherichia coli biofilm formation","volume":"141","author":"Wu","year":"2013","journal-title":"Food Chem."},{"key":"ref_14","first-page":"454","article-title":"Suppression of bacterial quorum sensing by citrus flavonoids","volume":"58","author":"Vikram","year":"2010","journal-title":"Food Sci. Nutr."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"325","DOI":"10.1007\/s00394-015-0852-y","article-title":"Interaction of dietary compounds, especially polyphenols, with the intestinal microbiota","volume":"54","author":"Tarko","year":"2015","journal-title":"Eur. J. Nutr."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"4471","DOI":"10.1007\/s00018-016-2302-2","article-title":"Morphological and ultrastructural changes in bacterial cells as an indicator of antibacterial mechanism of action","volume":"73","author":"Cushnie","year":"2016","journal-title":"Cell. Mol. Life Sci."},{"key":"ref_17","first-page":"943","article-title":"Quercetin inhibits biofilm formation by decreasing the production of extracellular polymeric substances","volume":"120","author":"Ouyang","year":"2016","journal-title":"J. Appl. Microbiol."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Li, Y.-L., Chu, Z.-Y., Liu, G.-M., Yang, S.-Q., and Zeng, H. (2022). The Derived Components of Gnaphalium hypoleucum DC. Reduce Quorum Sensing of Chromobacterium violaceum. Molecules, 27.","DOI":"10.3390\/molecules27154881"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"543974","DOI":"10.1155\/2014\/543974","article-title":"Importance of biofilms in urinary tract infections: New therapeutic approaches","volume":"2014","author":"Soto","year":"2014","journal-title":"Adv. Biol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"489","DOI":"10.1099\/jmm.0.46404-0","article-title":"Modulation of crystalline Proteus mirabilis biofilm development on urinary catheters","volume":"55","author":"Stickler","year":"2006","journal-title":"J. Med. Microbiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1038\/nrmicro2415","article-title":"The biofilm matrix","volume":"8","author":"Flemming","year":"2010","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_22","first-page":"MB-0001-2014","article-title":"Biofilm development","volume":"3","year":"2015","journal-title":"Microbiol. Spectr."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"a012427","DOI":"10.1101\/cshperspect.a012427","article-title":"Bacterial quorum sensing: Its role in virulence and possibilities for its control","volume":"2","author":"Rutherford","year":"2012","journal-title":"Cold Spring Harb. Perspect. Med."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Fydrych, D., Jeziurska, J., We\u0142na, J., and Kwieci\u0144ska-Pir\u00f3g, J. (2025). Potential Use of Selected Natural Compounds with Anti-Biofilm Activity. Int. J. Mol. Sci., 26.","DOI":"10.3390\/ijms26020607"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1089\/mdr.2012.0244","article-title":"Antibacterial activity and mode of action of ferulic and gallic acids against pathogenic bacteria","volume":"19","author":"Borges","year":"2013","journal-title":"Microb. Drug Resist."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"322","DOI":"10.1016\/j.ijantimicag.2009.12.011","article-title":"Antibiotic resistance of bacterial biofilms","volume":"35","author":"Bjarnsholt","year":"2010","journal-title":"Int. J. Antimicrob. 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