Table 1.

NCCLS conditions for antifungal susceptibility testing

CharacteristicNCCLS M27-A (135) NCCLS M38-P (133)
SuitabilityYeasts Conidium- and spore-forming fungi
Inoculum 0.5 × 103–2.5 × 103 CFU/ml 0.4 × 104–5 × 104CFU/ml
Inoculum standardization Spectrophotometric, with reference to a 0.5 McFarland BaSO4 turbidity standardSpectrophotometric, with specificatiion of a target optical density that varies by fungal genus
Test medium RPMI 1640, buffered to pH 7.0 with 0.165 M MOPS Same as M27-A
Format Macrodilution or microdilution Microdilution
Temp 35°C 35°C
Duration of incubation 48 h (Candida spp.), 72 h (C. neoformans) 24 h (Rhizopus spp.), 72 h (Pseudallescheria boydii), 48 h (most fungi, includingFusarium spp., Aspergillus spp., andSporothrix schenckii)
End point Optically clear well for amphotericin B, ∼80% reduction in growth (macrodilution testing with azoles), prominent decrease in turbidity (microdilution testing with flucytosine and the azole antifungals) Prominent growth reduction from control (∼50%) for flucytosine, fluconazole, and azoles; optically clear well for amphotericin B; the T-level revision will propose the use of an optically clear end point for intraconazole and the newer azoles (e.g., voriconazole)
QC isolates and drugs Two isolates of Candida against amphotericin B, flucytosine, fluconazole, voriconazole, ketoconazole, itraconazole, caspofungin (MK-0991), ravuconazole (BMS 207147), posaconazole (SCH 56592), and anidulafungin (LY303366, V-echinocandin) (14)Two isolates of Aspergillus against amphotericin B and intraconazole