Optimal Susceptibility Testing Conditions for Detection of Azole Resistance in Aspergillus spp.: NCCLS Collaborative Evaluation

DOI: 10.1128/AAC.45.6.1828-1835.2001

Article Figures & Data

Table 1.

Selected isolates of Aspergillus spp. used in this study

↵a Low itraconazole MICs (≤1.0 μg/ml) by M38-P, Etest, or other methods described in corresponding publication(s).
↵b Animals and patients responded to itraconazole treatment (isolates had low itraconazole MICs [<1.0 μg/ml]).
↵c These two isolates also had either a good (isolate 3) or decreased (isolate 5) response to posaconazole in a murine model.
↵d Animals and patients did not respond to itraconazole treatment (isolates had high itraconazole MICs [>8 μg/ml]).
↵e Voriconazole-resistant laboratory mutant.
↵f NA, not available.

Table 2.

Interlaboratory agreement on broth microdilution antifungal susceptibility for Aspergillusspp.^a

Antifungal agent and MIC criterion	% Agreement [all isolates (itraconazole-susceptible isolates)]
Antifungal agent and MIC criterion	RPMI	RPMI-2%	M3	M3-2%
Itraconazole
MIC-0	90 (92)	92 (94)	90 (91)	85 (85)
MIC-2	83 (89)	88 (94)	84 (92)	88 (97)
Posaconazole
MIC-0	91 (91)	88 (87)	94 (94)	86 (86)
MIC-2	96 (96)	95 (96)	93 (99)	91 (96)
Ravuconazole
MIC-0	93 (95)	87 (85)	94 (95)	88 (89)
MIC-2	88 (89)	90 (89)	85 (86)	81 (82)
Voriconazole
MIC-0	97 (97)	98 (99)	99 (100)	93 (92)
MIC-2	88 (96)	94 (95)	90 (92)	96 (96)

↵a Species tested were A. fumigatus ( n = 9 ), A. flavus( n = 3 ), and A. terreus ( n = 3 ); 48-h MICs are shown.

Table 3.

Itraconazole MICs for Aspergillus spp. in eight laboratories^a

Isolate(s) (no. tested) and MIC criterion	MIC range (MIC₉₀ or modal MIC)^b
Isolate(s) (no. tested) and MIC criterion	RPMI	RPMI-2%	M3	M3-2%
Itraconazole susceptible (12)
MIC-0	0.03–2 (1)	0.03–4 (0.5)	0.06–>8 (1)	0.06–>8 (2)
MIC-2	0.01–1 (0.2)	<0.008–0.5 (0.12)	<0.008–1 (0.2)	0.01–1 (0.2)
Itraconazole resistant (isolate no. 5)
MIC-0	8–>8 (>8)	8–>8 (>8)	2–>8 (>8)	2–>8 (>8)
MIC-2	0.06–>8 (2)	0.06–>8 (1)	<0.008–>8 (1)	<0.008–>8 (1)
Itraconazole resistant (isolate no. 6)
MIC-0	1–>8 (>8)	1–>8 (>8)	2–>8 (>8)	1–>8 (>8)
MIC-2	0.12–>8 (1)	0.12–>8 (0.5)	1–>8 (1)	0.2–>8 (1)
Voriconazole-resistant mutant (1)
MIC-0	0.5–>8 (2)	0.5–>8 (0.5)	1–>8 (>8)	1–>8 (>8)
MIC-2	0.06–0.5 (0.2)	0.03–0.5 (0.12)	0.06–0.5 (0.2)	0.01–0.2 (0.06)

↵a Species tested were A. fumigatus ( n = 9 ), A. flavus( n = 3 ), and A. terreus ( n = 3 ); see Table 1 for reported data regarding isolates 5 and 6; 48-h MICs are shown.
↵b MICs are reported in micrograms per milliliter; the MIC₉₀ is reported for susceptible isolates and the modal MIC is reported for single resistant isolates.

Table 4.

Posaconazole (SCH56592) MICs for Aspergillusspp. in eight laboratories^a

Isolate(s) (no. tested) and MIC criterion	MIC range (MIC₉₀ or modal MIC)^b
Isolate(s) (no. tested) and MIC criterion	RPMI	RPMI-2%	M3	M3-2%
Itraconazole susceptible (12)
MIC-0	0.01–0.5 (0.2)	0.03–2 (0.2)	0.03–0.5 (0.2)	0.03–>8 (0.5)
MIC-2	0.03–0.12 (0.06)	0.008–0.12 (0.06)	0.008–0.12 (0.06)	0.03–0.06 (0.06)
Itraconazole resistant (isolate no. 5)
MIC-0	0.2–1 (1)	0.2–2 (0.5)	0.5–2 (0.5)	0.2–2 (0.5)
MIC-2	0.03–0.5 (0.2)	0.03–0.2 (0.12)	<0.008–0.5 (0.5)	<0.008–0.5 (0.2)
Itraconazole resistant (isolate no. 6)
MIC-0	0.2–1 (0.5)	0.2–1 (0.5)	0.12–2 (1)	0.12–>8 (0.5)
MIC-2	0.06–0.5 (0.12)	0.01–0.2 (0.12)	0.01–1 (0.2)	0.03–0.5 (0.2)
Voriconazole-resistant mutant
MIC-0	0.12–>8 (0.2)	0.06–2 (0.12)	0.5–8 (0.5)	0.12–2 (0.2)
MIC-2	0.03–0.12 (0.06)	0.03–1 (0.03)	0.03–0.12 (0.03)	0.03–0.06 (0.03)

↵a Species tested were A. fumigatus ( n = 9 ), A. flavus( n = 3 ), and A. terreus ( n = 3 ); see Table 1 for reported data regarding isolates 5 and 6; 48-h MICs are shown.
↵b MICs are reported in micrograms per milliliter; the MIC₉₀ is reported for susceptible isolates and the model MIC is reported for single resistant isolates.

Table 5.

Ravuconazole (BMS-207147) MICs for Aspergillusspp. in eight laboratories^a

Isolate(s) (no. tested) and MIC criterion	MIC range (MIC₉₀ or modal MIC)^b
Isolate(s) (no. tested) and MIC criterion	RPMI	RPMI-2%	M3	M3-2%
Itraconazole susceptible (12)
MIC-0	0.12–4 (2)	0.12–>8 (1)	0.2–>8 (4)	0.2–>8 (4)
MIC-2	0.01–1 (1)	0.01–0.5 (0.5)	0.01–4 (1)	0.06–1 (1)
Itraconazole resistant (isolate no. 5)
MIC-0	0.2–0.5 (0.2)	0.12–1 (0.2)	0.2–8 (0.5)	0.12–4 (1)
MIC-2	0.01–0.2 (0.12)	0.03–0.12 (0.06)	<0.008–0.5 (0.12)	0.008–0.5 (0.06)
Itraconazole resistant (isolate no. 6)
MIC-0	2–8 (2)	1–>8 (2)	1–>8 (8)	2–>8 (8)
MIC-2	0.2–4 (0.5)	0.12–1 (1)	0.2–4 (2)	0.062–8 (2)
Voriconazole-resistant mutant (1)
MIC-0	2–>8 (4)	1–4 (2)	4–>8 (>8)	2–>8 (8)
MIC-2	0.12–4 (1)	0.06–1 (0.5)	0.06–2 (0.5)	0.03–1 (0.2)

↵a Species tested were A. fumigatus ( n = 9 ), A. flavus( n = 3 ), and A. terreus ( n = 3 ); see Table 1 for reported data regarding isolates 5 and 6; 48-h MICs are shown.
↵b MICs are reported in micrograms per milliliter; the MIC₉₀ is reported for susceptible isolates and the modal MIC is reported for single resistant isolates.

Table 6.

Voriconazole MICs for Aspergillus spp. in eight laboratories^a

Isolate(s) (no. tested) and MIC criterion	MIC range (MIC₉₀ or modal MIC)^b
Isolate(s) (no. tested) and MIC criterion	RPMI	RPMI-2%	M3	M3-2%
Itraconazole susceptible (12)
MIC-0	0.12–2 (1)	0.2–2 (1)	0.5–8 (4)	0.2–>8 (4)
MIC-2	0.01–2 (0.5)	<0.008–1 (1)	<0.008–1 (1)	0.12–1 (0.5)
Itraconazole resistant (isolate no. 5)
MIC-0	0.2–0.5 (0.2)	0.2–0.5 (0.2)	0.2–2 (0.5)	0.2–1 (0.5)
MIC-2 (0.12)	0.03–0.2 (0.12)	0.03–0.2 (0.06)	<0.008–0.2 (0.12)	0.03–0.12 (0.12)
Itraconazole resistant (isolate no. 6)
MIC-0	1–2 (1)	0.5–2 (1)	2–4 (4)	2–8 (2)
MIC-2	0.12–0.5 (0.5)	0.12–1 (0.2)	0.5–2 (1)	0.2–1 (0.5)
Voriconazole-resistant mutant (1)
MIC-0	2–>8 (4)	2–8 (4)	4–>8 (8)	4–>8 (8)
MIC-2	0.5–4 (0.5)	0.2–1 (1)	0.2–2 (0.5)	0.2–1 (0.5)

↵a Species tested were A. fumigatus ( n = 9 ), A. flavus( n = 3 ), and A. terreus ( n = 3 ); 48-h MICs are shown.
↵b MICs are reported in micrograms per milliliter; the MIC₉₀ is reported for susceptible isolates and the modal MIC is reported for single resistant isolates.

Table 7.

Triazole MIC ranges for the reference A. flavus ATCC 204304 isolate in eight laboratories

Antifungal agent and MIC criterion	MIC range^a
Antifungal agent and MIC criterion	RPMI	RPMI-2%	M3	M3-2%
Itraconazole
MIC-0	0.2–0.5	0.12–0.5	0.5–1	0.5–1
MIC-2^b	0.06–0.2	0.06–0.5	0.06–0.2	0.06–0.5
Posaconazole
MIC-0	0.06–0.5	0.06–0.5	0.12–0.2	0.12
MIC-2	0.03–0.12	0.03–0.06	0.01–0.12	0.03–0.06
Ravuconazole
MIC-0	0.5–4	0.5–2	1–4	0.5–4
MIC-2	0.12–1	0.06–1	0.12–1	0.06–2
Voriconazole
MIC-0	0.5–4	0.5–2	0.5–>8	0.5–4
MIC-2	0.12–0.5	0.06–0.5	0.12–1	0.12–2