Evaluation of the Microdilution, Etest and Disk Diffusion Methods for Antifungal Susceptibility Testing of Clinical Strains ofTrichosporonSpp.

Abstract

Trichosporon spp are well recognized as pathogens capable of causing invasive disease. Despite the increasing frequency and severity of trichosporonosis, data on the antifungal susceptibility of Trichosporon spp. are limited and recommendations for in vitro testing of this fungus are not included in the guidelines of the National Committee for Clinical Laboratory Standards. The purpose of this study was to determine the in vitro susceptibility of clinical Trichosporon isolates to systemic antifungals. We evaluated the in vitro activity of amphotericin B, fluconazole, itraconazole and voriconazole against 27 clinical isolates of Trichosporon spp. (14 T. mucoides and 13 T. asahii) using NCCLS M27-A2 reference microdilution, Etest and disk diffusion methods. In the microdilution and Etest methods Trichosporon spp. demonstrated relatively high minimum inhibitory concentrations (MICs) for fluconazole (MIC90 4 and 6 microg/ml, respectively) and relatively low MICs for voriconazole (MIC90 0.125 and 0.125 microg/ml, respectively). MICs for amphotericin B determined on antibiotic medium 3 were lower (MIC90 0.06 microg/ml) than those on RPMI (MIC90 1 microg/ml). Observed agreements were 81-100% according to these drugs. Disk diffusion zone diameters correlate inversely with MICs from dilution tests except for amphotericin B. Validation of the clinical significance of these observations demands determination of MIC breakpoints for Trichosporon and in vitro- in vivo correlation studies.

Selective Microbiologic Effects of Tea Extract on Certain Antibiotics Against Escherichia coli In Vitro

“…Nevertheless, the in vitro bacterial sensitivity test is still a routine procedure for clinical purposes, based on which proper antibiotics are selected to treat the infection. [24][25][26] …”

Head-to-Head Comparison of Inhibitory and Fungicidal Activities of Fluconazole, Itraconazole, Voriconazole, Posaconazole, and Isavuconazole against Clinical Isolates of Trichosporon asahii

“…While some of these used the CLSI or similar broth microdilution methodology (2, 4, 6, 18, 28-30), others applied Etest or disk diffusion assays (18,31,32). Using the CLSI M27-A2 method, MIC-2 as the endpoint, and 72 h as the incubation period, Thompson et al (29) reported MIC 90 values of 2, 0.06, 0.25, and 0.125 g/ml for fluconazole, voriconazole, posaconazole, and isavuconazole, respectively, for 40 isolates of T. asahii.…”

Genotyping and Antifungal Susceptibility of Trichosporon asahii Strains Isolated from the Clinical Samples in a University Training and Research Hospital in Turkey

“…The in vivo and in vitro activities of triazoles against Trichosporon species are higher than that of AMB (5,14). Trevino (13). In another study by Kalkanci et al, it has been emphasized that the efficacy of FCZ with MIC GM 13.66 was very low and the most active drug was VOR with 0.154 MIC GM (10).…”