{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T11:10:18Z","timestamp":1788952218193,"version":"build-2803163510"},"reference-count":37,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T00:00:00Z","timestamp":1788912000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Traditional Chinese Medicine Science and Technology Project of Zhejiang Province","award":["2024ZL940"],"award-info":[{"award-number":["2024ZL940"]}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>\n                      This study characterized the synergistic activity of dihydroquercetin combined with ceftazidime (CAZ) against mucoid\n                      <jats:italic>Pseudomonas aeruginosa<\/jats:italic>\n                      (mPA). The regimen primarily relieves biofilm-mediated phenotypic tolerance in CAZ-susceptible isolates, rather than reversing classical genetic resistance, while also enhancing efficacy against a minor proportion of intermediate\/resistant strains. We further clarified its mechanisms via membrane integrity tests, qRT-PCR of biofilm\/quorum-sensing genes and untargeted metabolomics, to provide experimental basis for treating refractory biofilm-related mPA infections.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Forty-one clinical mPA isolates were screened via the K-B assay. Checkerboard FICI and time-kill assays evaluated combined antibacterial effects Mucoid EPS semi\u2011quantitative staining assessed mucoid phenotype. Biofilm biomass and membrane permeability were measured by crystal violet staining and ALP leakage. qRT-PCR quantified biofilm\/quorum-sensing gene expression. UHPLC-Orbitrap untargeted metabolomics coupled with multivariate analysis identified differential metabolites. Statistics were analyzed using GraphPad Prism and the R package ropls.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      87.8% of the 41 mPA isolates were ceftazidime-susceptible. Mucoid EPS semi\u2011quantitative staining showed dihydroquercetin\u2011ceftazidime co\u2011treatment markedly repressed mucoid EPS, particularly in resistant mPA isolates. Over 90% of strains displayed synergistic (31.7%, FICI \u22640.5) or additive (61.0%, 0.5\u202f&amp;lt;\u202fFICI \u22641.0) responses to the combination. Time-kill curves showed the combination achieved a\u202f\u2265\u202f2 log\u2081\u2080 CFU\/mL reduction and suppressed early bacterial growth at 4\u20138\u202fh. Single drugs weakly inhibited biofilms, whereas co-treatment sharply lowered biofilm biomass (\n                      <jats:italic>p<\/jats:italic>\n                      \u202f&amp;lt;\u202f0.01). Dihydroquercetin increased membrane permeability in a time-dependent manner, with stronger effects in the combination group. qRT-PCR revealed co-treatment significantly downregulated lasR, rhlR, pslA, pelA and fliC (\n                      <jats:italic>p<\/jats:italic>\n                      \u202f&amp;lt;\u202f0.05). Metabolomics confirmed the combination triggered broader metabolic reprogramming, reducing virulence metabolites and biofilm precursors while elevating citric acid, a core TCA intermediate. KEGG enrichment highlighted perturbed valine\/leucine\/isoleucine biosynthesis, pyruvate metabolism and purine metabolism.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Dihydroquercetin synergizes with CAZ against mPA by disrupting biofilm\/membrane integrity, repressing quorum-sensing and biofilm-related genes, and remodeling bacterial metabolism. This combination can treat biofilm-associated mPA infections and validates dihydroquercetin as a plant-derived antibiotic adjuvant.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fmicb.2026.1945324","type":"journal-article","created":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T10:16:26Z","timestamp":1788948986000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Mechanisms of synergistic antibacterial and anti-biofilm effects of dihydroquercetin combined with ceftazidime against mucoid pseudomonas aeruginosa"],"prefix":"10.3389","volume":"17","author":[{"given":"Li","family":"Gao","sequence":"first","affiliation":[{"name":"Department of Blood Transfusion, The Affiliated Lihuili Hospital of Ningbo University","place":["Ningbo, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenjun","family":"Lu","sequence":"additional","affiliation":[{"name":"Department of Intensive Care Unit, The Affiliated Lihuili Hospital of Ningbo University","place":["Ningbo, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keda","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Blood Transfusion, The Affiliated Lihuili Hospital of Ningbo University","place":["Ningbo, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuedan","family":"Qiu","sequence":"additional","affiliation":[{"name":"Department of Clinical Laboratory, The Affiliated Lihuili Hospital of Ningbo University","place":["Ningbo, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qingcao","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Clinical Laboratory, The Affiliated Lihuili Hospital of Ningbo University","place":["Ningbo, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,9]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"2653","DOI":"10.3390\/microorganisms11112653","article-title":"Taxifolin as a Metallo-\u03b2-lactamase inhibitor in combination with Augmentin against Verona Imipenemase 2 expressing Pseudomonas aeruginosa","volume":"11","author":"Benin","year":"2023","journal-title":"Microorganisms"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"229","DOI":"10.1159\/000007294","article-title":"In vitro activity of ceftazidime, cefepime and imipenem on 1,005 Pseudomonas aeruginosa clinical isolates either susceptible or resistant to beta-lactams","volume":"46","author":"Bonfiglio","year":"2000","journal-title":"Chemotherapy"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"4976","DOI":"10.1128\/AAC.00650-12","article-title":"Mature Pseudomonas aeruginosa biofilms prevail compared to young biofilms in the presence of ceftazidime","volume":"56","author":"Bowler","year":"2012","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref4","doi-asserted-by":"publisher","first-page":"1274","DOI":"10.1099\/jmm.0.073163-0","article-title":"Dormant bacteria within Staphylococcus epidermidis biofilms have low inflammatory properties and maintain tolerance to vancomycin and penicillin after entering planktonic growth","volume":"63","author":"Cerca","year":"2014","journal-title":"J. Med. Microbiol."},{"key":"ref5","doi-asserted-by":"publisher","first-page":"1173","DOI":"10.3389\/fmicb.2015.01173","article-title":"Inhibiting N-acyl-homoserine lactone synthesis and quenching Pseudomonas quinolone quorum sensing to attenuate virulence","volume":"6","author":"Chan","year":"2015","journal-title":"Front. Microbiol."},{"key":"ref6","doi-asserted-by":"publisher","first-page":"3055","DOI":"10.3390\/molecules23123055","article-title":"Taxifolin Resensitizes multidrug resistance Cancer cells via uncompetitive inhibition of P-glycoprotein function","volume":"23","author":"Chen","year":"2018","journal-title":"Molecules"},{"key":"ref7","doi-asserted-by":"publisher","first-page":"169","DOI":"10.1093\/jac\/8.suppl_b.169","article-title":"Activity of ceftazidime against Pseudomonas aeruginosa from bacteraemic and fibrocystic patients","volume":"8","author":"Fleming","year":"1981","journal-title":"J. Antimicrob. Chemother."},{"key":"ref8","doi-asserted-by":"publisher","first-page":"434","DOI":"10.3390\/antibiotics10040434","article-title":"Adsorption of phenazines produced by Pseudomonas aeruginosa using Ast-120 decreases pyocyanin-associated cytotoxicity","volume":"10","author":"Hirakawa","year":"2021","journal-title":"Antibiotics"},{"key":"ref9","doi-asserted-by":"publisher","first-page":"322","DOI":"10.1016\/j.ijantimicag.2009.12.011","article-title":"Antibiotic resistance of bacterial biofilms","volume":"35","author":"H\u00f8iby","year":"2010","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref10","doi-asserted-by":"publisher","first-page":"7","DOI":"10.1016\/j.jcma.2017.07.012","article-title":"Bacterial biofilm and associated infections","volume":"81","author":"Jamal","year":"2018","journal-title":"J. Chin. Med. 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Mycobacteriol."},{"key":"ref13","doi-asserted-by":"publisher","first-page":"1546","DOI":"10.3390\/ijms18071546","article-title":"Taxifolin activates the Nrf2 anti-oxidative stress pathway in mouse skin epidermal Jb6 P+ cells through epigenetic modifications","volume":"18","author":"Kuang","year":"2017","journal-title":"Int. J. Mol. Sci."},{"key":"ref14","doi-asserted-by":"publisher","first-page":"4029","DOI":"10.3390\/nu13114029","article-title":"Antimicrobial effects of Inula viscosa extract on the in situ initial oral biofilm","volume":"13","author":"Kurz","year":"2021","journal-title":"Nutrients"},{"key":"ref15","doi-asserted-by":"publisher","first-page":"433","DOI":"10.3390\/antibiotics10040433","article-title":"The bacterial genomic context of highly trimethoprim-resistant DfrB dihydrofolate reductases highlights an emerging threat to public health","volume":"10","author":"Lemay-St-Denis","year":"2021","journal-title":"Antibiotics"},{"key":"ref16","doi-asserted-by":"publisher","first-page":"926758","DOI":"10.3389\/fcimb.2022.926758","article-title":"Virulence factors of Pseudomonas aeruginosa and Antivirulence strategies to combat its drug resistance","volume":"12","author":"Liao","year":"2022","journal-title":"Front. Cell. Infect. Microbiol."},{"key":"ref17","doi-asserted-by":"publisher","first-page":"e0262422","DOI":"10.1128\/mbio.02624-22","article-title":"Metabolic mechanism and physiological role of glycerol 3-phosphate in Pseudomonas aeruginosa Pao1","volume":"13","author":"Liu","year":"2022","journal-title":"MBio"},{"key":"ref18","doi-asserted-by":"publisher","first-page":"95","DOI":"10.1186\/s12866-022-02518-w","article-title":"Low-concentration iron promotes Klebsiella pneumoniae biofilm formation by suppressing succinic acid","volume":"22","author":"Liu","year":"2022","journal-title":"BMC Microbiol."},{"key":"ref19","doi-asserted-by":"publisher","first-page":"139","DOI":"10.1099\/jmm.0.001128","article-title":"Pseudomonas aeruginosa mexT is an indicator of Pao1 strain integrity","volume":"69","author":"Lovullo","year":"2020","journal-title":"J. Med. Microbiol."},{"key":"ref20","doi-asserted-by":"publisher","first-page":"996","DOI":"10.1080\/08927014.2024.2435027","article-title":"Inhibition of Staphylococcus aureus biofilm by quercetin combined with antibiotics","volume":"40","author":"Ma","year":"2024","journal-title":"Biofouling"},{"key":"ref21","doi-asserted-by":"publisher","first-page":"447","DOI":"10.1111\/lam.12211","article-title":"The involvement of rhamnolipids in microbial cell adhesion and biofilm development - an approach for control?","volume":"58","author":"Nickzad","year":"2014","journal-title":"Lett. Appl. Microbiol."},{"key":"ref22","doi-asserted-by":"publisher","first-page":"428","DOI":"10.1016\/j.jiac.2018.01.007","article-title":"Sub-minimum inhibitory concentrations of ceftazidime inhibit Pseudomonas aeruginosa biofilm formation","volume":"24","author":"Otani","year":"2018","journal-title":"J. Infect. 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Microbiol."},{"key":"ref26","doi-asserted-by":"publisher","first-page":"57","DOI":"10.1007\/s00253-023-12890-w","article-title":"Quercetin: a promising virulence inhibitor of Pseudomonas aeruginosa LasB in vitro","volume":"108","author":"Ren","year":"2024","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref27","doi-asserted-by":"publisher","first-page":"103","DOI":"10.1016\/j.jgar.2013.04.001","article-title":"Assessment of combination therapy by time kill curve analysis and chequerboard assay for treatment of multi-drug resistant Pseudomonas aeruginosa isolates","volume":"1","author":"Rizvi","year":"2013","journal-title":"J. Glob. Antimicrob. 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Anal."},{"key":"ref31","doi-asserted-by":"publisher","first-page":"296","DOI":"10.3390\/pathogens9040296","article-title":"In vivo antimicrobial and wound-healing activity of resveratrol, dihydroquercetin, and dihydromyricetin against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans","volume":"9","author":"Shevelev","year":"2020","journal-title":"Pathogens"},{"key":"ref32","doi-asserted-by":"publisher","first-page":"5793","DOI":"10.1128\/AAC.00548-15","article-title":"Effects of Klebsiella pneumoniae carbapenemase subtypes, extended-spectrum \u03b2-lactamases, and porin mutations on the in vitro activity of ceftazidime-avibactam against carbapenem-resistant K. pneumoniae","volume":"59","author":"Shields","year":"2015","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref33","doi-asserted-by":"publisher","first-page":"112066","DOI":"10.1016\/j.phytochem.2019.112066","article-title":"An insight into the health-promoting effects of taxifolin (dihydroquercetin)","volume":"166","author":"Sunil","year":"2019","journal-title":"Phytochemistry"},{"key":"ref34","doi-asserted-by":"publisher","first-page":"1743","DOI":"10.2217\/fmb.15.69","article-title":"Bacterial resistance in biofilm-associated bacteria","volume":"10","author":"Venkatesan","year":"2015","journal-title":"Future Microbiol."},{"key":"ref35","doi-asserted-by":"publisher","first-page":"2657","DOI":"10.3389\/fmicb.2018.02657","article-title":"Bacterial metabolism during biofilm growth investigated by (13)C tracing","volume":"9","author":"Wan","year":"2018","journal-title":"Front. Microbiol."},{"key":"ref36","doi-asserted-by":"publisher","first-page":"517462","DOI":"10.3389\/fmicb.2020.517462","article-title":"Traditional Chinese medicine Tanreqing inhibits quorum sensing systems in Pseudomonas aeruginosa","volume":"11","author":"Yang","year":"2020","journal-title":"Front. Microbiol."},{"key":"ref37","doi-asserted-by":"publisher","first-page":"3423","DOI":"10.3390\/ijms20143423","article-title":"Biofilms: the microbial \"protective clothing\" in extreme environments","volume":"20","author":"Yin","year":"2019","journal-title":"Int. J. Mol. 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