Alejandro Arboleda

Assessment of rose bengal versus riboflavin photodynamic therapy for inhibition of fungal keratitis isolates.

PURPOSE To compare the in vitro effect of rose bengal and riboflavin as photosensitizing agents for photodynamic therapy (PDT) on fungal isolates that are common causes of fungal keratitis. DESIGN Experimental study. METHODS Three isolates (Fusarium solani, Aspergillus fumigatus, Candida albicans) recovered from patients with confirmed fungal keratitis were used in the experiments. Isolates were grown on Sabouraud-Dextrose agar, swabbed, and prepared in suspension, and 1 mL aliquots were inoculated onto test plates in triplicate. Test plates were separated into 5 groups: Group 1, no treatment; Group 2, 0.1% rose bengal alone; Group 3, 518 nm irradiation alone; Group 4, riboflavin PDT (riboflavin + 375 nm irradiation); and Group 5, rose bengal PDT (rose bengal + 518 nm irradiation). Irradiation was performed over a circular area using either a green light-emitting diode (LED) array (peak wavelength: 518 nm) or an ultraviolet-A LED array (peak wavelength: 375 nm). Test plates were irradiated with an energy density of 5.4 J/cm(2). Later, plates were placed in a 30 C incubator and observed for growth. RESULTS Rose bengal-mediated PDT successfully inhibited the growth of all 3 fungal isolates in the irradiated area. All other groups exhibited unrestricted growth throughout the plate. CONCLUSIONS Rose bengal-mediated PDT successfully inhibited the growth of 3 types of fungi. No other experimental groups, including riboflavin-mediated PDT, had any inhibitory effect on the isolates. The results might be useful for the treatment of patients suffering from corneal infection.

Rose Bengal Photodynamic Antimicrobial Therapy: A Novel Treatment for Resistant Fusarium Keratitis

Purpose: To evaluate the efficacy of rose bengal PDAT for the management of a patient with multidrug-resistant Fusarium keratoplasticum keratitis unresponsive to standard clinical treatment. Methods: This case report presents a clinical case of F. keratoplasticum keratitis not responsive to standard medical care. In vitro studies from patients culture isolated responded to rose bengal PDAT. Patient received two treatments with rose bengal 0.1% and exposure to green light with a total energy of 2.7 J/cm2. Results: In vitro results demonstrated the efficacy of rose bengal PDAT a multidrug-resistant F. keratoplasticum species. There was complete fungal inhibition in our irradiation zone on the agar plates. In the clinical case, the patient was successfully treated with 2 sessions of rose bengal PDAT, and at 8-month follow-up, there was neither recurrence of infection nor adverse effects to report. Conclusions: Rose bengal PDAT is a novel treatment that may be considered in cases of aggressive infectious keratitis. Further studies are needed to understand the mechanisms of PDAT in vivo.

Comparison of continuous versus pulsed photodynamic antimicrobial therapy for inhibition of fungal keratitis isolates in vitro (Conference Presentation)

Fungal keratitis can lead to pain and impaired vision. Current treatment options include antifungal agents and therapeutic penetrating keratoplasty. An emerging option for the management of keratitis is photodynamic antimicrobial therapy (PDAT) which uses a photosensitizer rose bengal activated with green light. Utilizing a pulsed irradiation, rather than the standard continuous irradiation may have a similar antimicrobial effect with less total energy. This study is to compare pulsed and continuous rose bengal mediated PDAT for inhibition of six fungal isolates on agar plates: Fusarium solani, Fusarium keratoplasticum, Aspergillus fumigatus, Candida albicans, Paecilomyces variotti, and Pseudoallescheria boydii. Isolates were mixed with 0.1% rose bengal and exposed to three irradiation conditions: (1) 30-minute continuous (10.8J/cm2), (2) 15-minute continuous (5.4J/cm2), (3) 30-minute pulsed (5.4J/cm2). Plates were photographed at 72 hours and analyzed with custom software. At 72 hours, 30-minute continuous rose bengal mediated PDAT inhibited all six fungal species. Fungal inhibition was analogous between 30-minute continuous and 30-minute pulsed test groups, with the exception of A. fumigatus. The 15-minute continuous irradiation was less effective when compared to both 30-minute continuous and 30-minute pulsed groups. These in vitro results demonstrate the potential strength of pulsed rose bengal mediated PDAT as an adjunct treatment modality for fungal keratitis.