title: In-vitro activity of 5-fluorocytosine against 1,021 Spanish clinical isolates of Candida and other medically important yeasts.
abstract: The aim of this study was to determine the prevalence of primary resistance to 5-fluorocytosine (5FC) among clinical isolates of yeasts in Spain where this drug is not currently available for therapy. We have tested the in vitro activity of 5FC against 1,021 recent yeast clinical isolates, including 522 Candida albicans, 140 Candida parapsilosis, 68 Candida glabrata, 41 Candida dubliniensis, 50 Candida guilliermondii, 34 Candida tropicalis, 28 Candida krusei, 20 Candida famata, 11 Cryptococcus neoformans, 5 Cryptococcus albidus, 43 Rhodotorula spp., 24 Trichosporon spp., 5 Saccharomyces cerevisiae, 9 Pichia spp., and 21 isolates from other 11 yeast species. The MICs were determined by the ATB Fungus agar microdilution test (bioMerieux, France) and the following interpretive breakpoints were used: susceptible, > 4 microg/ml; intermediate, 8 to 16 microg/ml; resistant, > 32 microg/ml. 5FC was very active against Candida spp. and other medically important yeasts as 852 (83.4%) of the studied isolates were susceptible (MIC < 4 microg/ml). The species most susceptible to 5FC were C. dubliniensis (100%of isolates; MIC90, 0.25 microg/ml), C. famata (100% of isolates; MIC90, 0.25 microg/ml), C. guilliermondii (98%of isolates; MIC90, 0.25 microg/ml), C. glabrata (95.5% of isolates; MIC90, 0.25 microg/ml), and C. neoformans (90.9% of isolates; MIC90, 2 microg/ml). Primary resistance to 5FC was very uncommon, and a MIC > 32 microg/ml, indicator of in vitro resistance, was observed in 106 isolates (10.4%): 77 C. albicans (16.5% of isolates; MIC90, > 128 microg/ml), 9 C. parapsilosis (6.4% of isolates; MIC90, 8 microg/ml), 4 C. albidus (80% of isolates, MIC50, > 128 microg/ml), 3 C. glabrata (4.4% of isolates; MIC90, 0.25 microg/ml), 3 C. tropicalis (8.8% of isolates; MIC90, 4 microg/ml), 2 C. krusei (7.1% of isolates; MIC90, 8 microg/ml), 2 Rhodotorula spp. (4.6% of isolates, MIC90, 1 microg/ml), 8 Trichosporon spp. (33.3% of isolates; MIC90, 64 microg/ml), and 1 C. lipolytica (50% of isolates). Interestingly, most C. albicans (67 out of 77 isolates) resistant to 5FC were serotype B isolates.
authors.affiliation: Departamento de Inmunología, Microbiología y Parasitología, Facultad de Medicina y odontología, Universidad del País Vasco, Bilbao, Spain. oipquang@lg.ehu.es
authors.forename: Guillermo
authors.initials: G
authors.lastname: Quindós
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Ruesga
authors.forename: Estrella
authors.initials: E
authors.lastname: Martín-Mazuelos
authors.forename: Ricardo
authors.initials: R
authors.lastname: Salesa
authors.forename: Rocío
authors.initials: R
authors.lastname: Alonso-Vargas
authors.forename: Alfonso Javier
authors.initials: AJ
authors.lastname: Carrillo-Muñoz
authors.forename: Sonia
authors.initials: S
authors.lastname: Brena
authors.forename: Rosario
authors.initials: R
authors.lastname: San Millán
authors.forename: José
authors.initials: J
authors.lastname: Pontón
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects*; D005437:Flucytosine / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D013030:Spain; D015003:Yeasts / Q000187:drug effects
chemical_list: D000935:Antifungal Agents; D005437:Flucytosine