{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T16:54:38Z","timestamp":1785430478286,"version":"3.56.0"},"reference-count":30,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,5,9]],"date-time":"2026-05-09T00:00:00Z","timestamp":1778284800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004917","name":"Cancer Prevention and Research Institute of Texas","doi-asserted-by":"publisher","award":["RR220054"],"award-info":[{"award-number":["RR220054"]}],"id":[{"id":"10.13039\/100004917","id-type":"DOI","asserted-by":"publisher"}]},{"award":["RR220054"],"award-info":[{"award-number":["RR220054"]}],"id":[{"id":"https:\/\/ror.org\/0003xa228","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Governor\u2019s University Research Initiative"},{"name":"Chancellor\u2019s Research Initiative"},{"DOI":"10.13039\/501100001807","name":"S\u00e3o Paulo Research Foundation","doi-asserted-by":"crossref","award":["2025\/26084-6"],"award-info":[{"award-number":["2025\/26084-6"]}],"id":[{"id":"10.13039\/501100001807","id-type":"DOI","asserted-by":"crossref"}]},{"award":["2025\/26084-6"],"award-info":[{"award-number":["2025\/26084-6"]}],"id":[{"id":"https:\/\/ror.org\/02ddkpn78","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003593","name":"National Council for Scientific and Technological Development","doi-asserted-by":"publisher","award":["400468\/2024-6"],"award-info":[{"award-number":["400468\/2024-6"]}],"id":[{"id":"10.13039\/501100003593","id-type":"DOI","asserted-by":"publisher"}]},{"award":["400468\/2024-6"],"award-info":[{"award-number":["400468\/2024-6"]}],"id":[{"id":"https:\/\/ror.org\/03swz6y49","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Embrapii\u2014Basic Funding in Oncology"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pharmaceutics"],"abstract":"<jats:p>Background\/Objectives: Klebsiella pneumoniae is a major pathogen involved in both acute and chronic infections, characterized by high incidence and significant clinical severity. Over the past decade, resistance to traditional antimicrobial treatments has risen rapidly, highlighting the urgent need for innovative approaches. Light-based antimicrobial strategies, including antimicrobial photodynamic therapy (aPDT), offer a promising approach for addressing drug-resistant bacteria. Combining two photosensitizers (PSs) with antibiotics synergistically enhances ROS generation and multi-target bacterial damage, achieving superior antimicrobial efficacy at reduced PS, light and antibiotic doses while limiting resistance development. We evaluated the efficacy of aPDT using the photosensitizers (PSs) methylene blue (MB) and Photodithazine (PDZ), either alone or in combination with the antibiotic ciprofloxacin (CIP), gentamicin (GEN), or ceftriaxone (CEF), against K. pneumoniae. Methods: Bacterial suspensions were treated with PDZ (25\u2013200 \u00b5g\/mL) and\/or MB (5\u201320 \u00b5g\/mL) in the presence of CIP (0.005\u20134 \u00b5g\/mL), GEN (0.5\u201316 \u00b5g\/mL), or CEF (0.5\u201316 \u00b5g\/mL), followed by irradiation at either 15 J\/cm2 or 30 J\/cm2. Bacterial survival was assessed by colony-forming unit (CFU\/mL) quantification. Results: The combined application of photosensitizers and antibiotics demonstrated a synergistic bactericidal effect against planktonic K. pneumoniae. The combined use of two PSs with antibiotics markedly reduced the antibiotic dose required to achieve a comparable bactericidal effect. Conclusions: This study highlights the potential of combining aPDT with conventional antibiotics as a promising strategy to combat drug-resistant infections, offering enhanced antimicrobial efficacy while allowing for reduced antibiotic dosages to achieve comparable therapeutic outcomes.<\/jats:p>","DOI":"10.3390\/pharmaceutics18050587","type":"journal-article","created":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T15:45:34Z","timestamp":1779291934000},"page":"587","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Dual-Photosensitizer Antimicrobial Photodynamic Therapy (DaPDT) and Its Combination with Antibiotics: A New Investigation Modality Against Klebsiella pneumoniae"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6063-904X","authenticated-orcid":false,"given":"Koteswara Rao","family":"Yerra","sequence":"first","affiliation":[{"name":"Department of Biomedical Engineering, College of Engineering, Texas A&M University, College Station, TX 77843, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vanderlei S.","family":"Bagnato","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, College of Engineering, Texas A&M University, College Station, TX 77843, USA"},{"name":"S\u00e3o Carlos Institute of Physics, University of S\u00e3o Paulo, S\u00e3o Carlos 13566-590, SP, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"100947","DOI":"10.1016\/j.lanmic.2024.07.010","article-title":"Antimicrobial resistance: A concise update","volume":"6","author":"Ho","year":"2025","journal-title":"Lancet Microbe"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Baran, A., Kwiatkowska, A., and Potocki, L. 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