Inactivation kinetics and lethal dose analysis of antimicrobial blue light and photodynamic therapy
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Photodiagnosis and Photodynamic Therapy
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Background: Antimicrobial Photodynamic therapy (A-PDT) has been used to treat infections. Currently, microbial
inactivation data is reported presenting survival fraction averages and standard errors as discrete points
instead of a continuous curve of inactivation kinetics. Standardization of this approach would allow clinical
protocols to be introduced globally, instead of the piecemeal situation which currently applies.
Methods: To this end, we used a power-law function to fit inactivation kinetics and directly report values of
lethal doses (LD) and a tolerance factor (T) that informs if inactivation rate varies along the irradiation procedure.
A deduced formula was also tested to predict LD for any given survival fraction value. We analyzed the
photoantimicrobial effect caused by red light activation of methylene blue (MB-APDT) and by blue light (BL)
activation of endogenous microbial pigments against 5 clinically relevant pathogens.
Results: Following MB- APDT, Escherichia coli and Staphylococcus aureus cells become increasingly more tolerant
to inactivation along the irradiation process (T < 1). Klebsiella pneumoniae presents opposite behavior, i.e., more
inactivation is observed towards the end of the process (T > 1). P. aeruginosa and Candida albicans present
constant inactivation rate (T˜1). In contrast, all bacterial species presented similar behavior during inactivation
caused by BL, i.e., continuously becoming more sensitive to blue light exposure (T > 1).
Conclusion: The power-law function successfully fit all experimental data. Our proposed method precisely
predicted LD and T values. We expect that these analytical models may contribute to more standardized methods
for comparisons of photodynamic inactivation efficiencies.
Como referenciar
SABINO, CAETANO P.; WAINWRIGHT, MARK; ANJOS, CAROLINA dos; SELLERA, FABIO P.; BAPTISTA, MAURICIO S.; LINCOPAN, NILTON; RIBEIRO, MARTHA S. Inactivation kinetics and lethal dose analysis of antimicrobial blue light and photodynamic therapy. Photodiagnosis and Photodynamic Therapy, v. 28, p. 186-191, 2019. DOI: 10.1016/j.pdpdt.2019.08.022. Disponível em: http://repositorio.ipen.br/handle/123456789/30437. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.