Effects of Photodynamic Inactivation on the Growth and Antifungal Susceptibility of Rhizopus oryzae
- 16 Downloads
Mucormycosis is an aggressive and high-mortality opportunistic fungal infection, especially in immunocompromised patients. Conventional antifungals or surgery showed a limited effect on this disease. The antimicrobial photodynamic therapy (aPDT) has been proven to be a promising therapeutic choice against multiple pathogenic fungi. We evaluated the effect of aPDT by using methylene blue (MB) combined with a light emitting diode (LED) on the viability of Rhizopus oryzae, as well as the antifungal susceptibility after aPDT treatment in vitro. A total of six strains were included in this study; MB (8, 16, and 32 μg/ml) was chosen for the photosensitizer, and a light source of LED (635 ± 10 nm, 12 J/cm2) device was used to active it. aPDT with MB (32 μg/ml) and LED was highly effective in cell growth inhibition and exhibited colony-forming unit reductions of up to 4.3log10. The minimal inhibitory concentration ranges of itraconazole, posaconazole, and amphotericin B decreased from > 32 μg/ml to 4–8 μg/ml, 8–16 μg/ml to 0.5–2 μg/ml, and 2–4 μg/ml to 0.25–0.5 μg/ml, respectively, after pre-treatment with MB (8 μg/ml) and LED. In conclusion, aPDT with MB and LED was a promising therapeutic option against R. oryzae infections alone or combined with antifungal agents. However, further investigation is needed to determine the potential for clinic therapy and to elucidate the underlying mechanism.
KeywordsPhotodynamic inactivation Fungi Rhizopus oryzae Antifungal susceptibility
This work was supported by National Natural Science Foundation of China (31400131 to Lujuan Gao and 81401677 to Yi Sun), and Hubei Province Health and Family Planning Scientific Research Project (WJ2018H178 to Yi Sun).
Compliance with Ethical Standards
Conflict of interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
- 5.Husain S, Alexander BD, Munoz P, Avery RK, Houston S, Pruett T, Jacobs R, Dominguez EA, Tollemar JG, Baumgarten K, Yu CM, Wagener MM, Linden P, Kusne S, Singh N. Opportunistic mycelial fungal infections in organ transplant recipients: emerging importance of non-Aspergillus mycelial fungi. Clin Infect Dis. 2003;37(2):221–9.CrossRefGoogle Scholar
- 9.Gao L, Jiang S, Sun Y, Deng M, Wu Q, Li M, Zeng T. Evaluation of the Effects of Photodynamic Therapy Alone and Combined with Standard Antifungal Therapy on Planktonic Cells and Biofilms of Fusarium spp. and Exophiala spp. Front Microbiol. 2016; 7: 617.Google Scholar
- 17.Clinical and Laboratory Standards Institute. Reference method for broth dilution antifungal susceptibility testing of filamentous fungi; approved standard-2nd ed. CLSI document M38-A2. CLSI, Wayne, PA. 2008.Google Scholar
- 19.Ribeiro AP, Andrade MC, da Silva Jde F, Jorge JH, Primo FL, Tedesco AC, Pavarina AC. Photodynamic inactivation of planktonic cultures and biofilms of Candida albicans mediated by aluminum–chloride–phthalocyanine entrapped in nanoemulsions. Photochem Photobiol. 2013;89(1):111–9.CrossRefGoogle Scholar
- 20.Carrera ET, Dias HB, Corbi SCT, Marcantonio RAC, Bernardi ACA, Bagnato VS, Hamblin MR, Rastelli ANS. The application of antimicrobial photodynamic therapy (aPDT) in dentistry: a critical review. Laser Phys. 2016;26(12).Google Scholar