Article Figures & Data
Figures
- FIG. 1.
Interference of MGM agar with voriconazole disks for A. terreus (A) and with caspofungin disks for P. lilacinus (B), where low MICs corresponded to very small or no inhibition zone diameters. These conflicting results were not observed on MH agar.
- FIG. 2.
Correlation of broth microdilution MICs and posaconazole 5-μg disk diffusion zone diameters on MH agar for 483 mold isolates in three laboratories. MICs were determined at the recommended times (24 to 72 h), and zone diameters, in millimeters, were determined at the optimal incubation times (16 to 24 h and 48 h). ZD, zone diameter.
- FIG. 3.
Correlation of broth microdilution MICs and itraconazole 10-μg disk diffusion zone diameters on MH agar for 483 mold isolates in three laboratories. MICs were determined at the recommended times (24 to 72 h), and zone diameters, in millimeters, were determined at the optimal incubation times (16 to 24 h and 48 h). ZD, zone diameter.
- FIG. 4.
Correlation of broth microdilution MICs and voriconazole 1-μg disk diffusion zone diameters on MH agar for 483 mold isolates in three laboratories. MICs were determined at the recommended times (24 to 72 h), and zone diameters, in millimeters, were determined at the optimal incubation times (16 to 24 h and 48 h). ZD, zone diameter.
- FIG. 5.
Correlation of broth microdilution MECs and caspofungin 5-μg disk (BBL) diffusion zone diameters on MH agar for 483 mold isolates in three laboratories. MECs were determined at the recommended times (24 to 48 h), and zone diameters, in millimeters, were determined at the optimal incubation times (16 to 24 h and 48 h). ZD, zone diameter.
- FIG. 6.
Correlation of broth microdilution MICs and amphotericin B 10-μg disk diffusion zone diameters on MH agar for 483 mold isolates in three laboratories. MICs were determined at the recommended times (24 to 72 h), and zone diameters, in millimeters, were determined at the optimal incubation times (16 to 24 h and 48 h). ZD, zone diameter.
Tables
- TABLE 1.
Species and numbers of mold isolates tested at three of five centers
Species No. of isolates Absidia corymbifera 15 Alternaria sp. 23 Bipolaris spicifera 18 Aspergillus fumigatus 56 A. flavus 38 A. niger 38 A. terreus 40 A. nidulans 31 Fusarium solani 29 F. moniliforme 28 F. oxysporum 20 Mucor circinelloides 17 Mucor ramosissimus 5 Rhizopus arrhizus 37 Rhizopus microsporus var. rhizopodiformis 10 Paecilomyces lilacinus 24 Scedosporium apiospermum 28 S. prolificans 26 Total 483a ↵a Another set of 72 isolates was tested at another two centers to obtain reproducibility data.
- TABLE 2.
Reproducibility of inhibition zone diameters, in millimeters, obtained by the disk diffusion method with five antifungal agents for 72 mold isolates at two of the five centersa
Antifungal agent and mediumb % within 2-SD zone at: 24 h 48 h 72 h Itra MH 96 91 88 MGM 87 82 82 Posa MH 97 95 92 MGM 96 96 94 Vori-1 MH 97 94 93 MGM 97 95 90 Vori-10 MH 92 93 92 MGM 92 93 92 Cas-BBL MH 100 96 95 MGM 96 94 87 Cas-Oxoid MH 100 97 97 MGM 100 100 97 Amb MH 95 95 95 MGM 100 95 91 ↵a Percentages of replicate zone diameters within 2 standard deviations of the mean; each of the 72 isolates was tested on 3 different days in two of the five laboratories with each antifungal agent. Inhibition zone diameters, in millimeters, on both MH and MGM agar were read at 16 to 24, 48, and 72 h.
↵b Itra, itraconazole 10-μg disk; Posa, posaconazole 5-μg disk; Cas-BBL and Cas-Oxoid, caspofungin 5-μg disks from two sources; Vori-1 and Vori-10, voriconazole 1-μg and 10-μg disks, respectively; Amb, amphotericin B 10-μg disk.
- TABLE 3.
Inhibition zone diameters obtained on MH agar by the disk diffusion method for two QC isolatesa
QC isolateb and antifungal agent Zone range in millimeters (% agreement) at: 24 h 48 h 72 h Paecilomyces variotii ATCC 3630 Itra 25-31 (99) 23-31 (94) 24-31 (97) Posa 35-46 (100) 37-45 (97) 37-44 (97) Vori-1 40-53 (94) 41-53 (94) 41-53 (100) Vori-10 56-64 (97) 60-71 (86) 61-73 (89) Cas-BBL 23-29 (100) 23-30 (97) 24-30 (97) Cas-Oxoid 23-34 (100) 23-34 (97) 22-33 (89) Amb 13-22 (94) 9-19 (83) 10-19 (89) Candida krusei ATCC 6258 Itra 21-30 (100) 20-29 (100) 20-28 (100) Posa 31-43 (97) 30-41 (97) 30-41 (97) Vori-1 29-38 (100) 25-35 (100) 24-36 (97) Vori-10 47-59 (92) 46-60 (97) 53-61 (92) Cas-BBL 14-24 (100) 18-27 (97) 17-25 (97) Cas-Oxoid 21-29 (100) 21-30 (100) 21-32 (100) Amb 19-27 (100) 15-25 (97) 13-25 (97) ↵a Tests were performed 5 to 16 times for each isolate in each of the five laboratories for each disk and incubation time on MH agar.
↵b Itra, itraconazole 10-μg disk; Posa, posaconazole 5-μg disk; Cas-BBL and Cas-Oxoid, caspofungin 5-μg disks from two sources; Vori-1 and Vori-10, voriconazole 1-μg and 10-μg disks, respectively; Amb, amphotericin B 10-μg disk.
- TABLE 4.
Correlation between inhibition zone diameters (in millimeters) obtained by the disk diffusion method and reference M38-A MICs (amphotericin B and triazoles) and MECs (caspofungin) for 483 mold isolates at three of the five centersa
Antifungal agent and incubation time (h)b Correlation coefficient (R value)c for: MH MGM Itra 24 0.79 ND 48 0.75 0.58 72 0.74 0.67 Posa 24 0.77 ND 48 0.71 0.65 72 0.71 0.71 Vori-1 24 0.85 ND 48 0.83 0.87 72 0.82 0.53 Vori-10 24 0.83 ND 48 0.80 0.85 72 0.83 0.58 Cas-BBL 24 0.92 ND 48 0.88 0.96 72 0.90 0.87 Cas-Oxoid 24 0.93 ND 48 0.89 0.88 72 0.90 0.87 Amb 24 0.68 ND 48 0.43 0.32 72 0.31 0.54 ↵a MICs were read at 24 h (zygomycetes), 72 h (Scedosporium sp.), and 48 h (other species) as recommended in the CLSI M38-A document. Caspofungin MECs were read at 24 h (all species except for Scedosporium sp., which were read at 48 h). Each MIC or MEC was plotted against inhibition zone diameters in millimeters obtained on both MH and MGM agars at each of the three incubation times; results from three centers were combined for linear regression analysis.
↵b Itra, itraconazole 10-μg disk; Posa, posaconazole 5-μg disk; Cas-BBL and Cas-Oxoid, caspofungin 5-μg disks from two sources; Vori-1 and Vori-10, voriconazole 1-μg and 10-μg disks, respectively; Amb, amphotericin B 10-μg disk.
↵c ND, not determined. The 48-h results for MGM medium encompassed 24- and 48-h zones of inhibition; 71% of the 24-h results were reported as no growth.
- TABLE 5.
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 S I R Minor Major Very major Posaconazole BMD 78 9 13 Disk, 5 μg 83 4 13 8.1 0.2 0.2 92 Itraconazole BMD 54 11 35 Disk, 10 μg 52 8 40 12.8 2.5 1.8 83 Voriconazole BMD 59 9 32 Disk, 1 μg 56 1 43 9.7 4.6 0.2 86 Caspofungin BMD 51 3 46 Disk, 5 μg, BBL 50 1 49 3.3 1 0.2 96 Amphotericin B BMD 49 24 27 Disk, 10 μg 58 12 30 23.1 2.7 1.7 73 ↵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.
