title: Fungicidal effect of photodynamic therapy against fluconazole-resistant Candida albicans and Candida glabrata.
abstract: Although photodynamic therapy (PDT) has shown great promise for the inactivation of Candida species, its effectiveness against azole-resistant pathogens remains poorly documented. This in vitro study describes the association of Photogem® (Photogem, Moscow, Russia) with LED (light emitting diode) light for the photoinactivation of fluconazole-resistant (FR) and American Type Culture Collection (ATCC) strains of Candida albicans and Candida glabrata. Suspensions of each Candida strain were treated with five Photogem® concentrations and exposed to four LED light fluences (14, 24, 34 or 50 min of illumination). After incubation (48 h at 37 °C), colonies were counted (CFU ml(-1)). Single-species biofilms were generated on cellulose membrane filters, treated with 25.0 mg l(-1) of Photogem® and illuminated at 37.5 J cm(-2). The biofilms were then disrupted and the viable yeast cells present were determined. Planktonic suspensions of FR strains were effectively killed after PDT. It was observed that the fungicidal effect of PDT was strain-dependent. Significant decreases in biofilm viability were observed for three strains of C. albicans and for two strains of C. glabrata. The results of this investigation demonstrated that although PDT was effective against Candida species, fluconazole-resistant strains showed reduced sensitivity to PDT. Moreover, single-species biofilms were less susceptible to PDT than their planktonic counterparts.
authors.affiliation: Department of Dental Materials and Prosthodontics, Araraquara Dental School, São Paulo State University-UNESP, Araraquara, SP, Brazil.
authors.forename: Lívia Nordi
authors.initials: LN
authors.lastname: Dovigo
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Pavarina
authors.forename: Ewerton Garcia de Oliveira
authors.initials: EG
authors.lastname: Mima
authors.forename: Eunice Teresinha
authors.initials: ET
authors.lastname: Giampaolo
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Vergani
authors.forename: Vanderlei Salvador
authors.initials: VS
authors.lastname: Bagnato
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects; D002176:Candida albicans / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D041221:Candida glabrata / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D002177:Candidiasis / Q000188:drug therapy* / Q000382:microbiology; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology*; D006801:Humans; D008027:Light; D008826:Microbial Sensitivity Tests; D010778:Photochemotherapy
chemical_list: D000935:Antifungal Agents; D015725:Fluconazole