Evaluation of the in vitro activity of caspofungin against bloodstream isolates of Candida species from cancer patients: comparison of Etest and NCCLS reference methods

Laverdière, Michél; Restieri, C.; Habel, F.

doi:10.1016/s0924-8579(02)00240-6

Cited by 19 publications

(18 citation statements)

References 9 publications

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“…The comparability of these results suggests that it should be possible to harmonize these approaches for testing echinocandins. Similarly, we confirm the results of previous studies regarding the excellent agreement between the Etest and CLSI methods for the testing of echinocandins (7,26,33). In contrast to the observations of others (1, 12, 13), we did not find the Etest to be any more sensitive than either the CLSI or EUCAST BMD method for the detection of fks mutants, nor did we find higher echinocandin MIC results for mutant strains tested by the Etest versus the CLSI or EUCAST method.…”

Section: Resultssupporting

confidence: 90%

“…Despite the broad utilization of these agents (5,19,38,42), longitudinal surveillance studies have documented the excellent and sustained potency of all three echinocandins since the introduction of caspofungin in 2001 (6,10,11,14,15,(30)(31)(32). Although resistance to echinocandins remains uncommon among cases of invasive candidiasis, sporadic examples of clinical failure associated with elevated MICs to one or more of these agents have been reported (1,3,16,26,39). In the majority of these cases, it has been demonstrated that the clinically resistant isolates of the Candida species C. albicans, C. glabrata, C. tropicalis, and C. krusei have acquired resistance mutations in the fks1 and/or fks2 gene (encoding the glucan synthase [GS] target enzyme) associated with altered GS enzyme kinetics for all three echinocandins (3, 12, 13, 16-18, 23-25, 30-32, 39, 41).…”

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confidence: 99%

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Comparison of European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Etest Methods with the CLSI Broth Microdilution Method for Echinocandin Susceptibility Testing of Candida Species

et al. 2010

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The antifungal broth microdilution (BMD) method of the European Committee on Antibiotic Susceptibility Testing (EUCAST) and the Etest agar diffusion method were compared with the Clinical and Laboratory Standards Institute (CLSI) BMD method M27-A3 for anidulafungin, caspofungin, and micafungin susceptibility testing of 133 clinical isolates of Candida species. The isolates were characterized for the presence or absence of fks1 and/or fks2 gene mutations and included 34 isolates of C. glabrata (4 mutant strains), 32 of C. albicans (1 mutant strain), 25 of C. parapsilosis, 19 of C. guilliermondii, 12 of C. tropicalis (2 mutant strains), and 11 of C. krusei. Excellent essential agreement (EA; within 2 dilutions) between the CLSI and EUCAST and CLSI and Etest MIC results was observed. The overall EA between the EUCAST and CLSI results ranged from 89.5% (caspofungin) to 99.2% (micafungin), whereas the EA between the Etest and CLSI results ranged from 90.2% (caspofungin) to 93.2% (anidulafungin). The categorical agreement (CA) between methods for each antifungal agent was assessed using previously determined epidemiological cutoff values (ECVs). Excellent CA (>90%) was observed for all comparisons between the EUCAST and CLSI results with the exceptions of C. glabrata and caspofungin (85.3%) and C. krusei and caspofungin (54.5%). The CA between the Etest and CLSI results was also excellent for all comparisons, with the exception of C. krusei and caspofungin (81.8%). All three methods were able to differentiate wild-type (WT) strains from those with fks mutations. With anidulafungin as the test reagent, the CLSI method identified 5 of 7 mutant strains, whereas the EUCAST method and the Etest identified 6 of 7 mutant strains. With either caspofungin or micafungin as the test reagent, the CLSI method identified all 7 mutant strains and the EUCAST method identified 6 of 7 mutant strains. The Etest identified all 7 mutant strains using caspofungin as the reagent. All three test methods showed a high level of agreement and of ability to distinguish fks mutant strains of Candida species from WT strains using each of the echinocandins.

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Section: Resultssupporting

confidence: 90%

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confidence: 99%

Comparison of European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Etest Methods with the CLSI Broth Microdilution Method for Echinocandin Susceptibility Testing of Candida Species

et al. 2010

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“…Nevertheless, in routine clinical microbiology laboratories, alternative methods such as the commercially available agar diffusion technique Etest are commonly used. The Etest is a reproducible and reliable technique for the determination of in vitro caspofungin activity, and good agreement with reference techniques is obtained (1,5,13,21,28).Caspofungin resistance in Candida spp. remains uncommon (27).…”

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confidence: 74%

Detection of Caspofungin Resistance in Candida spp. by Etest

2008

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The caspofungin susceptibilities of 28 Candida sp. clinical isolates, including 8 caspofungin-resistant isolates characterized by mutations in the Fks1 protein, were determined by the Etest in RPMI and AM3 media. Good discrimination between wild-type and mutant isolates was obtained. These results suggest that the Etest is valuable for the detection of caspofungin resistance in Candida spp.Most of the large surveillance studies on the in vitro susceptibility of Candida species isolates to caspofungin have been performed by using the reference broth microdilution techniques of the CLSI (25, 27) and 7,9). Nevertheless, in routine clinical microbiology laboratories, alternative methods such as the commercially available agar diffusion technique Etest are commonly used. The Etest is a reproducible and reliable technique for the determination of in vitro caspofungin activity, and good agreement with reference techniques is obtained (1,5,13,21,28).Caspofungin resistance in Candida spp. remains uncommon (27). However, several clinical case reports have been published on infections with Candida species isolates exhibiting high caspofungin MICs, some of which were associated with treatment failure (2, 8, 11, 14, 15, 18-20, 22, 23, 26, 30). In several cases, resistance was confirmed in animal models (15,19,26), and mutations in the fks1 gene were associated with the resistance phenotype (2,17,18,20,22,26). It has been shown that mutations in Fks1 are sufficient to confer reduced susceptibility to caspofungin on Candida spp. (26). Even though high MICs have been recorded using the Etest on a few Candida isolates (2, 19), this technique has never been evaluated for its ability to detect caspofungin resistance. We recently characterized a collection of Candida albicans, C. tropicalis, and C. krusei isolates with decreased susceptibility to caspofungin, associated with various Fks1 mutations (10). The aim of the present study was to evaluate the Etest for its ability to discriminate between wild-type (caspofungin-susceptible) and Fks1 mutant (caspofungin-resistant) isolates of Candida spp.The clinical isolates were collected at the French National Reference Center for Mycoses and Antifungals as part of our surveillance activities. All isolates were identified to the species level by standard mycological procedures including the assimilation patterns obtained with the commercialized ID32C strips (bioMérieux, Marcy-l'Etoile, France). For all C. albicans isolates, a specific PCR amplification (12) was performed to exclude C. dubliniensis. In a recent study (10), we sequenced and translated (to obtain the deduced protein sequence) the two hot spot (HS) regions of the fks1 gene, HS1 and HS2, for 28 clinical isolates, including Candida albicans (n ϭ 25), C. tropicalis (n ϭ 2), and C. krusei (n ϭ 1), for which caspofungin MICs were determined by the AFST-EUCAST method (29). MICs of Ն0.5 g/ml recorded in AM3 medium were associated with mutations in the deduced Fks1 sequence (6 C. albicans, 1 C. tropicalis, and 1 C. krusei isolate), w...

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“…For example, whereas some authors found caspofungin MIC ranges against isolates of C. albicans from 0.03 to 1 g/ml (12,14,16,21,23,26), other researchers have reported higher ranges of 0.25 to 4 g/ml (5,9,15). For tests with C. tropicalis, the highest caspofungin MIC from some laboratories (14,16) was at or below the lowest MIC reported from others (5,9,15,21). Differences of this order may represent intrinsic differences in the susceptibility of the panels of isolates tested, or they may indicate interlaboratory disparities in susceptibility tests with caspofungin.…”

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Interlaboratory Comparison of Results of Susceptibility Testing with Caspofungin against Candida and Aspergillus Species

et al. 2004

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Seventeen laboratories participated in a study of interlaboratory reproducibility with caspofungin microdilution susceptibility testing against panels comprising 30 isolates of Candida spp. and 20 isolates of Aspergillus spp. The laboratories used materials supplied from a single source to determine the influence of growth medium (RPMI 1640 with or without glucose additions and antibiotic medium 3 [AM3]), the same incubation times (24 h and 48 h), and the same end point definition (partial or complete inhibition of growth) for the MIC of caspofungin. All tests were run in duplicate, and end points were determined both spectrophotometrically and visually. The results from almost all of the laboratories for quality control and reference Candida and Aspergillus isolates tested with fluconazole and itraconazole matched the NCCLS published values. However, considerable interlaboratory variability was seen in the results of the caspofungin tests. For Candida spp. the most consistent MIC data were generated with visual "prominent growth reduction" (MIC 2 ) end points measured at 24 h in RPMI 1640, where 73.3% of results for the 30 isolates tested fell within a mode ؎ one dilution range across all 17 laboratories. MIC 2 at 24 h in RPMI 1640 or AM3 also gave the best interlaboratory separation of Candida isolates of known high and low susceptibility to caspofungin. Reproducibility of MIC data was problematic for caspofungin tests with Aspergillus spp. under all conditions, but the minimal effective concentration end point, defined as the lowest caspofungin concentration yielding conspicuously aberrant hyphal growth, gave excellent reproducibility for data from 14 of the 17 participating laboratories.

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Evaluation of the in vitro activity of caspofungin against bloodstream isolates of Candida species from cancer patients: comparison of Etest and NCCLS reference methods

Cited by 19 publications

References 9 publications

Comparison of European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Etest Methods with the CLSI Broth Microdilution Method for Echinocandin Susceptibility Testing of Candida Species

Comparison of European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Etest Methods with the CLSI Broth Microdilution Method for Echinocandin Susceptibility Testing of Candida Species

Detection of Caspofungin Resistance in Candida spp. by Etest

Interlaboratory Comparison of Results of Susceptibility Testing with Caspofungin against Candida and Aspergillus Species

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