In vitro susceptibility testing of Fonsecaea pedrosoi to antifungals

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Catalina de BEDOUT, Beatriz L. GÓMEZ, Angela RESTREPO
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP) 1997
• Subjects: Antifungal drugs; Fonsecaea pedrosoi; Susceptibility testing; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1590/S0036-46651997000300004; https://doaj.org/article/dce05a0c2bd348f085399ac70815c50b

Based on the difficulties experienced in the treatment of chromoblastomycosis, 12 primary human isolates of F. pedrosoi, were tested for their in vitro susceptibility to various antimycotics. We adapted the recommendations of the NCCLS for yeasts and followed the indications for mold testing from other authors in order to determine their MIC’s and the MLC’s. It was found that a significant proportion of the isolates were resistant to 3 of the 4 antimycotics tested, as revealed by high MIC values, as follows: 33% were resistant to amphotericin B (AMB), 58.3% to 5 fluocytosine (5 FC) and 66.7% to fluconazole (FLU). Contrarywise, none of the isolates proved resistant to itraconazole (ITZ). Determination of the MLC’s revealed that a larger proportion of the isolates were not killed by AMB, 5 FC (91.7%), FLU (100%) or even, ITZ (41.7%). These data indicate that it would be desirable to determine the susceptibility of F. pedrosoi before initiating therapy, in order to choose the more effective antifungal and avoid clinical failure Testes de suscetibilidade in vitro de Fonsecaea pedrosoi a antifúngicos Baseados nas dificuldades experimentadas no sucesso do tratamento da cromoblastomicose, 12 isolamentos humanos primários do F. pedrosoi foram examinados para a sua suscetibilidade in vitro aos vários antifúngicos. Nos adaptamos às recomendações da NCCLS feitas para leveduras e, seguimos as indicações para fungos filamentosos testados dadas por outros autores para as determinações dos MIC’s e dos MCLS. Nossos resultados mostraram que uma proporção significativa dos isolados testados foi resistente a três ou quatro dos antifúngicos experimentados, como revelaram os altos valores do MIC; assim, 33% dos isolados foram resistentes à anfotericina-B (AMB) 58,3% à fluorocitosina (5FC) e 66,7% ao fluconazole (FLU); pelo contrário, nenhum dos isolados examinados mostrou-se resistente ao itraconazole (ITZ). As determinações dos MLC revelaram que grande proporção dos isolados não foram mortos nem pela AMB (91,7%) 5FC (91,7%) FLU ...