Photodynamic therapy for pythiosis

Abstract

Background -Pythiosis is a life-threatening disease caused by Pythium insidiosum. Photodynamic therapy (PDT) is an alternative treatment to surgery that uses the interaction of a photosensitizer, light and molecular oxygen to cause cell death.Objectives -To evaluate the effect of PDT on the in vitro growth of P. insidiosum and in an in vivo model of pythiosis.Methods -For in vitro studies, two photosensitizers were evaluated: a haematoporphyrin derivative (Photogem â ) and a chlorine (Photodithazine â ). Amphotericin B was also evaluated, and the control group was treated with sterile saline solution. All experiments (PDT, porphyrin, chlorine and light alone, amphotericin B and saline solution) were performed as five replicates. For in vivo studies, six rabbits were inoculated with 20,000 zoospores of P. insidiosum, and an area of 1 cm 3 was treated using the same sensitizers. The PDT irradiation was performed using a laser emitting at 660 nm and a fluence of 200 J ⁄ cm 2 . Rabbits were clinically evaluated daily and histopathological analysis was performed 72 h after PDT.Results -For in vitro assays, inhibition rates for PDT ranged from 60 to 100% and showed better results in comparison to amphotericin B. For the in vivo assays, after PDT, histological analysis of lesions showed a lack of infection up to 1 cm in depth.Conclusions and clinical importance -In vitro and in vivo studies showed that PDT was effective in the inactivation of P. insidiosum and may represent a new approach to treating pythiosis. Accepted 13 July 2012 Sources of Funding: Fundaçã o de Amparo à Pesquisa do Estado de Sã o Paulo -FAPESP (grants 2008 ⁄ 03511-8 and 2010 ⁄ 02890-5) and FUNDUNESP (grant 42 ⁄ 11).

Pythium insidiosum: inhibitory effects of propolis and geopropolis on hyphal growth

“… 15 Pires et al reported that photodynamic therapy was effective both in vitro and in vivo in the inactivation of Pythium insidiosum , representing a new approach for treating pythiosis. 16 …”

“…The susceptibility of Pythium insidiosum isolates to propolis or geopropolis was determined by measuring the diameter (mm) of radial growth of the colony at 24, 48 and 168 h (7 days) of incubation. All cultures were photographed and the colonies diameter was achieved using the software Image J (image processing and analysis in JAVA; http://rsbweb.nih.gov/ij ), as described by Pires et al 16 Diameters at the angles 0, 45, 90 and 135° of each plate were recorded in mm.…”

Treating Pythiosis with Antibacterial Drugs Targeting Protein Synthesis: An Overview

“…Further clinical evidence is necessary to ascertain these compounds and therapies' true potential and practical applicability in a clinical setting. [33][34][35][36][37][38][39][40][41]…”

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.

“…In recent years, due to its efficiency and low invasive character, antimicrobial photodynamic therapy (aPDT) arises as a promising alternative approach to conventional antifungal medications, which has been demonstrated effective against multiple pathogenic fungi in vitro (Lyon et al, 2013 ; Pires et al, 2013 ; Arboleda et al, 2014 ; Morton et al, 2014 ; Nunes Mario et al, 2014 ; Baltazar et al, 2015 ) and applied successfully in vivo against cutaneous and subcutaneous mycoses (Gilaberte et al, 2011 ; Lyon et al, 2011b ; Souza et al, 2014 ). In addition, aPDT could be a useful approach for the control of biofilms, and has been proposed for the growth control of oral candida (Pereira et al, 2011 ; Pereira Gonzales and Maisch, 2012 ).…”