Agreement of inhibition zone diameters (disk diffusion method) with MICs or MECs (M38-A method) according to assigned susceptible, intermediate, and resistant categories for 483 mold isolates with five antifungal agents as obtained in three laboratories

Antifungal agent, method, and mediuma% of MICs by interpretive categoryb% Error% Agreementc
SIRMinorMajorVery major
    Disk, 5 μg834138.10.20.292
    Disk, 10 μg5284012.82.51.883
    Disk, 1 μg561439.74.60.286
    Disk, 5 μg, BBL501493.310.296
Amphotericin B
    Disk, 10 μg58123023.12.71.773
  • a BMD, MICs and MECs, in micrograms per milliliter, were determined at the recommended incubation times (24 to 48 h for caspofungin and 24 to 72 h for the other agents) by the CLSI M38-A broth microdilution method. Disk inhibition zone diameters, in millimeters, were determined with the optimal medium (MH agar) and incubation times (16 to 24 h and 48 h) by the disk diffusion method.

  • b Percentages of MICs or MECs and inhibition zone diameters, in millimeters, that were within the assigned posaconazole, itraconazole, voriconazole, and caspofungin categories (S [susceptible], MIC or MEC of ≤1 μg/ml, ≥17 mm; I [intermediate], MIC or MEC of 2 μg/ml, 14 to 16 mm; R [resistant], MIC or MEC of ≥4 μg/ml, ≤13 mm) and amphotericin B MIC and zone diameter categories (susceptible, MIC of ≤1 μg/ml, >15 mm; intermediate, MIC of 2 μg/ml, 13 to 14 mm; resistant, MIC of ≥4 μg/ml, 12 mm).

  • c Percent categorical agreement between inhibition zone diameters, in millimeters, and MIC or MEC results.