Photodynamic fungicidal efficacy of hypericin and dimethyl methylene blue against azole‐resistant Candida albicans strains. Issue 1 (12th June 2013)

• Record Type: Journal Article
• Authors: Paz‐Cristobal, M. P.; Royo, D.; Rezusta, A.; Andrés‐Ciriano, E.; Alejandre, M. C.; Meis, J. F.; Revillo, M. J.; Aspiroz, C.; Nonell, S.; Gilaberte, Y.
• Is Part Of: Mycoses. Volume 57:Issue 1(2014)
• Page Start: 35
• Page End: 42
• Publication Date: 2013-06-12
• Subjects: Pathogenic fungi -- Periodicals; Medical mycology -- Periodicals; 616.969
• DOI: 10.1111/myc.12099
• Languages: English
• ISSNs: 0933-7407

Abstract

<abstract abstract-type="main" id="myc12099-abs-0001"> <title>Summary</title> <p>Antimicrobial photodynamic therapy (aPDT) is an emerging alternative to treat infections based on the use of photosensitisers (PSs) and visible light. To investigate the fungicidal effect of PDT against azole‐resistant <italic>Candida albicans</italic> strains using two PSs with a different mechanism of action, hypericin (HYP) and 1, 9‐dimethyl methylene blue (DMMB), comparing their efficacy and the reactive oxygen species (ROS) species involved in their cytotoxicity. Azole‐resistant and the azole‐susceptible <italic>C. albicans</italic> strains were used. Solutions of 0.5 and 4 McFarland inoculum of each <italic>Candida</italic> strain were treated with different concentrations of each PS, and exposed to two light‐emitting diode light fluences (18 and 37 J cm<sup>−2</sup>). Mechanistic insight was gained using several ROS quenchers. The minimal fungicidal concentration of HYP for ≥3 log<sub>10</sub> CFU reduction (0.5 McFarland) was 0.62 μmol l<sup>−1</sup> for most strains, whereas for DMMB it ranged between 1.25 and 2.5 μmol l<sup>−1</sup>. Increasing the fluence to 37 J cm<sup>−2</sup> allowed to reduce the DMMB concentration. Higher concentrations of both PSs were required to reach a 6 log<sub>10</sub> reduction (4 McFarland). H<sub>2</sub>O<sub>2</sub> was the main phototoxic species involved in the fungicidal effect of HYP‐aPDT whereas <sup>1</sup>O<sub>2</sub> was more important for DMMB‐based treatments. aPDT with either HYP or DMMB is effective in killing of <italic>C. albicans</italic> strains independent of their azole resistance pattern. HYP was more efficient at low fungal concentration and DMMB at higher concentrations.</p> </abstract>