Multicenter Comparison of the VITEK 2 Antifungal Susceptibility Test with the CLSI Broth Microdilution Reference Method for Testing Amphotericin B, Flucytosine, and Voriconazole against Candida spp

Abstract

A fully automated commercial antifungal susceptibility test system (VITEK 2; bioMérieux, Inc., Hazelwood, MO) was compared in three different laboratories with the Clinical and Laboratory Standards Institute (formerly the NCCLS) reference broth microdilution method (BMD) by testing 2 quality control strains, 10 reproducibility strains, and 426 isolates of Candida spp. against amphotericin B, flucytosine, and voriconazole. Reference BMD MIC endpoints were established after 24 and 48 h of incubation. VITEK 2 system MIC endpoints were determined spectrophotometrically after 9.1 to 27.1 h of incubation (mean, 12 to 14 h). Excellent essential agreement (within 2 dilutions) between the VITEK 2 system and the 24-and 48-h BMD MICs was observed for all three antifungal agents: amphotericin B, 99.1% and 97%, respectively; flucytosine, 99.1% and 98.8%, respectively; and voriconazole, 96.7% and 96%, respectively. Both intra-and interlaboratory agreements were >98% for all three drugs. The overall categorical agreements between the VITEK 2 system and BMD for flucytosine and voriconazole were 98.1 to 98.6% at the 24-h BMD time point and 96.9 to 97.4% at the 48-h BMD time point. The VITEK 2 system reliably detected flucytosine and voriconazole resistance among Candida spp. and demonstrated excellent quantitative and qualitative agreement with the reference BMD method.

Anticandidal effect of endophytic bacteria isolated from Equisetum arvense L. against Candida albicans and Candida glabrata

“…More than 17 diverse Candida species are well-known etiological agents of human illness, while more than 90% of persistent infections are caused by C. albicans and C. glabrata [2][3][4] . As a frequent source of systemic mycoses, C. albicans can colonize both external and internal surfaces on common healthy individuals.…”

A Novel Flucytosine-Resistant Yeast Species, Candida pseudoaaseri, Causes Disease in a Cancer Patient

“…The results for the single antifungal agents were comparable, independent of the system that was used (CLSI reference method, Etest, Vitek 2, or Micronaut). It is known that the Etest correlates well with the CLSI reference method for determining the susceptibility of Candida isolates (3,4,5,11,34) and that the results from the YST card of Vitek 2 have a good correlation with the results from the standard method (9,11,36,37). In contrast to both C. aaseri strains, VK065094…”

Future therapies targeted towards eliminatingCandidabiofilms and associated infections

“…is not about non-albicans Candida species. The conclusion of the particular subsection should also be re-phrased as authors conclude that efflux pumps play a significant role in antifungal resistance of C. albicans biofilms (pg 6; lines 42-43), but earlier on the authors state that the activity of efflux pumps was insignificant in polyene and echinocandins resistance strains (pg 6; lines [17][18]. Furthermore, authors should exercise caution on generalizing about drug resistance, as most studies in the subsection concern data only on fluconazole resistance and there is one study on the activity of caspofungin against Candida displaying fluconazole resistance.…”