Optimizing the bactericidal effect of pulsed blue light on Propionibacterium acnes - A correlative fluorescence spectroscopy study

Propionibacterium acnes infection is the eighth most prevalent disease, affecting 80% of people worldwide. Resistance to antibiotics has been on the rise; over 40% of acne infections now resist commonly used topical and oral anti-acnes antibiotics, making treatment difficult. In our effort to refine...

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Bibliographic Details
Published in:Journal of photochemistry and photobiology. B, Biology Biology, 2020-01, Vol.202, p.111701-111701, Article 111701
Main Authors: Bumah, Violet Vakunseh, Masson-Meyers, Daniela Santos, Tong, William, Castel, Chris, Enwemeka, Chukuka Samuel
Format: Article
Language:English
Subjects:
Acne
Antibiotics
Antimicrobial therapy
Bacteria
Correlation analysis
Disk Diffusion Antimicrobial Tests
Exposure
Fluorescence
Fluorescence spectroscopy
Infections
Intervals
Irradiance
Light
Light effects
P. Acnes
Printed LEDs
Propionibacterium acnes
Propionibacterium acnes - radiation effects
Pulsed blue light
Spectrometry, Fluorescence
Thermodynamics
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Summary:Propionibacterium acnes infection is the eighth most prevalent disease, affecting 80% of people worldwide. Resistance to antibiotics has been on the rise; over 40% of acne infections now resist commonly used topical and oral anti-acnes antibiotics, making treatment difficult. In our effort to refine blue light as an alternative safe clinically effective treatment, we determined if 100% bacterial suppression is attainable at ultralow irradiances and radiant energies, and explored the relationship between bacterial suppression and fluorescence during treatment. P. acnes were irradiated in vitro repeatedly three times per day at 3- or 4-hour intervals over three or more days, using 3 or 5 J/cm2 radiant energy of 450 nm pulsed blue light (PBL) at irradiances as low as 2 mW/cm2. In another series of experiments, we measured changes in P. acnes fluorescence as bacteria were repeatedly irradiated at various radiant exposures over three to four days. Our results showed that (1) 33% PBL, applied three times per day at 3-hour intervals each day over a three-day period at 2 mW/cm2 irradiance and 5 J/cm2 radiant exposure, resulted in100% bacterial suppression (7 log10 reduction), (2) the absorbed 450 nm light caused P. acnes to fluoresce predominantly in the red spectrum, with the fluorescence diminishing correlatively as treatment was repeated at 3-hour intervals and rising significantly during long periods of no treatment, and (3) treatment at 3-hour intervals gave better results than treatment at 4-hour intervals. •Ultralow irradiation with pulsed blue light gives 100% bacterial suppression.•P. acnes chromophores absorb blue light and fluoresce in the red spectrum.•The fluorescence decreasing with irradiation and increasing without irradiation.•The 3-hour interval of treatment correlated more with P. acnes replication cycle.
ISSN:1011-1344
1873-2682
DOI:10.1016/j.jphotobiol.2019.111701