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Targeting planktonic uropathogens and Escherichia coli biofilm with photodynamic therapy mediated by methylene blue and potassium iodide

2026-10-01Artigo de investigação Acesso aberto
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dc.contributor.authorSilva, Daniela
dc.contributor.authorMendonça, Inês
dc.contributor.authorVieira, Cátia
dc.contributor.authorNeves, M. Graça P. M. S.
dc.contributor.authorFaustino, M. Amparo
dc.contributor.authorBartolomeu, Maria
dc.contributor.authorAlmeida, Adelaide
dc.date.accessioned2026-09-10T09:42:38Z
dc.date.available2026-09-10T09:42:38Z
dc.date.issued2026-10-01
dc.description.abstractUrinary tract infections (UTIs) are among the most common infections worldwide, with many hospital-acquired cases linked to biofilm formation on urinary catheter surfaces. The growing problem of antimicrobial resistance limits the effectiveness of conventional antibiotics, and antimicrobial photodynamic therapy (aPDT) has emerged as a promising alternative. This approach is based on the combination of a photosensitizer (PS), dioxygen, and visible light to reduce bacterial concentration without promoting resistance. In this study, the potential of aPDT in controlling UTIs was evaluated using a well-studied PS, methylene blue (MB), alone or in the presence of potassium iodide (KI). Ex vivo assays in urine were conducted using the five most common UTI-causing bacteria: Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Proteus mirabilis, and Pseudomonas aeruginosa. MB alone effectively photoinactivated E. coli, P. mirabilis, and E. faecalis in planktonic form, with limited activity against K. pneumoniae and P. aeruginosa. The addition of KI significantly enhanced the photodynamic effect against all tested strains, resulting in a reduced treatment time, and was also effective against mixed bacterial populations in the planktonic state. The efficacy of the treatments was further evaluated against E. coli cells within biofilms formed on urinary catheter surfaces. The combined action of MB and KI successfully controlled E. coli biofilms, achieving reductions of 3.9 (> 99.987%) and 6.0 log10 CFU mL−1 after one and two aPDT treatment cycles, respectively. Overall, these findings highlight MB + KI-mediated aPDT as a promising strategy for the photoinactivation of planktonic uropathogens and E. coli biofilms formed on urinary catheter surfaces.eng
dc.identifier.doi10.1016/j.jphotobiol.2026.113551
dc.identifier.eid105048619897
dc.identifier.other74aedc45-7f5c-4e23-b336-87ef344a10b1
dc.identifier.pmid42667816
dc.identifier.urihttp://hdl.handle.net/10400.14/59307
dc.identifier.wos001864645600001
dc.language.isoeng
dc.peerreviewedyes
dc.publisherElsevier B.V.
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/
dc.subjectAntimicrobial photodynamic therapyeng
dc.subjectBiofilmseng
dc.subjectCatheterseng
dc.subjectEnterococcus faecaliseng
dc.subjectEscherichia colieng
dc.subjectKlebsiella pneumoniaeeng
dc.subjectMethylene blue, polymicrobialeng
dc.subjectPlanktonic bacteriaeng
dc.subjectProteus mirabiliseng
dc.subjectPseudomonas aeruginosaeng
dc.subjectUrinary tract infectionseng
dc.titleTargeting planktonic uropathogens and Escherichia coli biofilm with photodynamic therapy mediated by methylene blue and potassium iodide
dc.typeresearch article
dspace.entity.typePublication
oaire.citation.volume283
oaire.versionhttp://purl.org/coar/version/c_970fb48d4fbd8a85

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