Atividade in vitro de antifúngicos em biofilmes de Candida

• Autor(a) principal: Pereira, Núbia Pontes
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/9240
• topic: Candida; Biofilme; Suscetibilidade; Antifúngicos; Infecções; Biofilm; Susceptibility; Antifungals; Infections; BIOLOGIA E FISIOLOGIA DOS MICROORGANISMOS::MICOLOGIA

C. albicans infections may be favored by tissue damages such insertion of medical devices that function as a substrate for fungus growth. This growth can occur in the form of three-dimensional structures formed by yeast and hyphae, coated with a matrix of extracellular polymeric material, forming a biofilm. This agregated of cells is characterized by having greater resistance to host defenses and antifungals, which makes hard treating these infections. This study aimed to determine the kinetics of biofilm formation by isolates of Candida sp. and to evaluate the antifungal susceptibility of plancktonic and sessile cells. We evaluated 10 isolates of C. albicans from different materials, isolated and identified by standardized methods. The minimum inhibitory concentrations (MICs) and minimal fungicidal concentrations (MFCs) of amphotericin B, fluconazole, voriconazole and itraconazole to plancktonic cells were performed according to protocol M27-A3 of Clinical Laboratory Standard Institute (CLSI). Verification of kinetics of biofilms’ formation was assessed at 24 h, 48 h, 72 h and 96 h of incubation at 37 ° C and in vitro susceptibility of sessile cells, was evaluated using the MTT (3 - [4,5-Dimethyl-2-Thiazy] -2,5- Diphenyl-2H-Tetrazolium bromide) assay. The analysis of kinetics at 24 h showed that all isolates produced biofilm and the highest metabolic activity occurred within 48h of growth. Significant differences, on the metabolic activity of biofilms were observed on strains U02, M02 and V60, which produced the highest amount of biofilm with 48 h of growth. MIC values obtained for plancktonic cells ranged from 1 to 8 mg/mL for fluconazole; between 0.0625 to 1 mg/mL for itraconazole; between 0.0312 to 0.25 g/mL for voriconazole; and between 0.25 to 2 mg/mL for amphotericin B. The MFC was twice the MIC for all isolates. For the values obtained for fluconazole the MICS50 ranged from 8 mg/mL to > 1024 mg/mL and MICS80 ≥ 1024 mg/mL. MICS50 for itraconazole ranged from 4 mg/mL to > 16 g/mL and MICS80 ≥ 16 g/mL. The MICS50 for voriconazole showed values between 4 mg/mL and > 16 g/mL and MICS80 ≥ 16 g/mL. Amphotericin B had MICS50 values of 0.25 mg / mL to > 16 g/mL and values MICS80 of 2 mg/mL to > 16 g/mL. We could demonstrate an increased resistance of biofilms to major antifungal drugs by evaluating the susceptibility of C. albicans isolates as plancktonic and sessile cells. These results show the need of new therapeutic or preventive strategies to reduce the mortality rate of patients with infections associated with Candida biofilms.