Comparison of the ATB® Fungus 2 with the AFST-EUCAST for in vitro susceptibility testing of Candida spp

The increase of diseases caused by Candida spp., and the treatment failures, has underscored the need for testing the susceptibilities to antifungal agents. The commercial panel ATB® Fungus 2 was compared with the reference testing method of the European Subcommittee on Antifungal Susceptibility Testing of the Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST) for the evaluation of the susceptibility of isolates of Candida spp. to three agents. The percentage of agreement was calculated based on the minimum inhibitory concentrations. There was a high correlation for AMB (100% қ = 1.0 Bhapkar coefficient p = 1.0); while it was lower with azoles (85%, қ = 0.41, p = Bhapkar coefficient 0.02 and 83.0%, қ = 0.15, Bhapkar coefficient p = 0.0006, respectively). The ATB® Fungus 2 and AFST-EUCAST are fully comparable methods for testing the susceptibility to AMB and to lesser extend comparable for ITR and FCA.

El aumento de infecciones por Candida spp. y de las fallas en los tratamientos, suscitan la necesidad de pruebas de susceptibilidad. Se comparó la marca comercial ATB® Fungus 2 con la técnica estándar del Subcomité para las Pruebas de Sensibilidad Antifúngica de la Unión Europea, de la Sociedad de Microbiología Clínica y Enfermedades Infecciosas (AFST-EUCAST) para evaluar la susceptibilidad de aislamientos de Candida spp. a tres antifúngicos. Con base en las concentraciones inhibitorias mínimas se calculó el porcentaje de acuerdo. La concordancia para anfotericina B (AMB) fue alta (100% қ = 1.0, Coeficiente de Bhapkarp = 1.0); para itraconazol (ITR) y fluconazol (FCA) fue inferior (85% қ = 0.41, Coeficiente de Bhapkarp =0.02 y 83.0 %, қ = 0.15, Coeficiente de Bhapkarp = 0.0006, respectivamente). Por lo tanto, ambas técnicas son comparables para la evaluación de la susceptibilidad a AMB; con los azoles el porcentaje de acuerdo es menor.

Comparison of ATB FUNGUS 2 and VITEK-2 Antifungal Susceptibility (AST-YS01) Tests for Candida Species Isolated from Blood Culture / 대한임상미생물학회지

BACKGROUND: The VITEK-2 yeast susceptibility test (AST-YS01; bioMerieux, Hazelwood, MO, USA) has recently been introduced as a fully automated, commercial antifungal susceptibility test system that determines MIC endpoints spectrophotometrically, thereby eliminating subjective errors. We compared the ATB FUNGUS 2 (bioMerieux) and VITEK-2 (AST-YS01) systems to the CLSI M27 method for susceptibility testing of Candida isolates. METHODS: We tested 59 Candida species that were isolated from blood cultures at Wonju Christian Hospital between September 2008 and August 2009. We compared MIC results for amphotericin B, flucytosine, fluconazole and voriconazole using the ATB FUNGUS 2 and VITEK-2 (AST-YS01) tests to those obtained by the CLSI M27 broth microdilution method. RESULTS: Within two-fold dilutions of MICs, the agreement of the ATB FUNGUS 2 and VITEK-2 (AST-YS01) tests with the CLSI method according to antifungal agents were: amphotericin B, 100% vs. 100% flucytosine, 100% vs. 100% fluconazole, 83.6% vs. 98.3% and voriconazole, 83.6% vs. 96.7%, respectively. The categorical discrepancies for fluconazole and voriconazole were 20.4% and 18.6% for ATB FUNGUS 2, and 6.8% and 0% for VITEK-2 (ASTYS01). There were no major errors for fluconazole and voriconazole in either ATB FUNGUS 2 or VITEK-2 (AST-YS01) tests. CONCLUSION: The VITEK-2 system (AST-YS01) appears to be rapid and highly correlative with the CLSI method, suggesting that it is effective for antifungal susceptibility testing for Candida species in clinical settings.

Antifungal Susceptibility Testing of Candida Species Using ATB FUNGUS 2 / 대한피부과학회지

BACKGROUND: Because of recently increasing reports of resistance of Candida (C.) species to antifungal agents, it is necessary to perform antifungal susceptibility testing. ATB FUNGUS 2 (bioMerieux, France) is an easy-to-perform in-vitro antifungal susceptibility test. OBJECTIVE: The purpose of the study was to investigate the minimal inhibitory concentration (MIC) of antifungal agents against Candida species isolated from skin lesion using ATB FUNGUS 2. METHODS: Eighty two clinical isolates of Candida species (including 56 C. albicans, 14 C. parapsilosis, 7 C. guilliermondii, 5 C. glabrata) were testeding ATB FUNGUS 2. MICs against itraconazole (ICZ), fluconazole (FCZ), flucytosine (FC) and amphotericin B (AMP) were read after 24 hours incubation. RESULTS: MIC of ICZ was or =2.0microgram/ml on four strains (3 C. albicans, 1 C. glabrata) and 0.25~0.5microgram/ml on five strains (1 C. parapsilosis, 3 C. guilliermondii, 1 C. glabrata). MIC of FCZ was 128microgram/ml on 3 C. albicans and 16microgram/ml on 1 C. parapsilosis. MIC of FC was 64microgram/ml on 6 C. albicans. MIC of AMP was all (100.0%) <0.5microgram/ml. CONCLUSION: ATB FUNGUS 2 represented a simple and valuable method for antifungal susceptibility testing of Candida species.

The Evaluation of Clinical Utility of ATB FUNGUS 2 for Antifungal Susceptibility Testing in Candida Species / 대한임상미생물학회지

BACKGROUND: Although the National Committee for Clinical Laboratory Standards (NCCLS) defined a standard reference broth microdilution method for testing the susceptibility of Candida species to antifungal drugs, many clinical laboratories require easier but reliable alternatives for routine antifungal susceptibility testing. We evaluated ATB FUNGUS 2 (bioMerieux, France.; ATB) compared to the method recommended by the NCCLS (NCCLS). METHODS: A total of 28 strains of Candida species consecutively isolated from blood and CSF cultures at Asan Medical Center from April to June 2004 were tested. In addition, 12 strains comprising C. krusei (3), C. glabrata (7) and C. guilliermondii (2) from the collection of Chonnam National University Hospital were included in the study. These strains were tested for minimum inhibitory concentrations (MICs) against flucytosine (FC), fluconazole (FZ), itraconazole (IZ) and amphotericin B (AB) by both of ATB and NCCLS. In NCCLS, MICs were read using a spectrophotometer after 24 and 48 hour-incubation. RESULTS: The concordance rates of MICs between ATB and NCCLS after 24 hour-incubation were 100%, 75%, 89% and 96% within two-fold dilution and 100%, 97%, 97%, 100% within four-fold dilution for FC, FZ, IZ and AB, respectively. For C. krusei, all three FC and FZ-resistant strains were either intermediate or SDD and one IZ-resistant strain was SDD in ATB, respectively. One C. tropicalis strain resulted in AB MICs of 0.5 microgram/mL in NCCLS, but 2 microgram/mL in ATB. CONCLUSIONS: ATB showed good concordance rates with NCCLS after 24 hour-incubation. ATB appears to be a useful alternatives to NCCLS for routine antifungal susceptibility tests. However, ATB needs further evaluation with more clinical strains, especially those resistant to antifungal agents.