Photodynamic inactivation of Rhizopus oryzae – in vitro study

During the COVID-19 pandemic, several complications arose in infected patients, one of them being mucormycosis, which is an extremely aggressive fungal disease with a high mortality rate, especially in patients with compromised immune systems. Most cases of mucormycosis are caused by the fungus Rhizopus oryzae, also known as black fungus, with 90% of cases affecting the rhinocerebral site. The treatment tools used are based on high doses of amphotericin B and posaconazole, associated with surgical resections when possible. However, even with aggressive antifungal treatment, the estimated attributable mortality rate is high [1]. In the absence of surgical debridement of the infected tissue, antifungal treatment alone is not curative. So there is a need for development of adjuvant treatments. Antimicrobial Photodynamic Therapy (aPDT) may constitute an auxiliary therapeutic option for mucormycosis [2]. Due to the lack of reports on the photodynamic inactivation of R. oryzae, we investigated different protocols Photodithazine® (PDZ) as a photosensitizer. The response on the fungus growing rate under distinct treatment parameters as photosensitizer concentration, incubation time, and association with surfactant, will be presented for both white and black hyphal phases, and infective spore phase. Preliminary results show the potential use of photodynamic therapy for the inactivation and growth control of the R. oryzae.