Comparison of the VITEK 2 antifungal susceptibility system with Etest using clinical isolates of Candida species / Comparación de los métodos de sensibilidad antifúngica Vitek 2 y Etest con cepas clínicas del género Candida

Background. Candida species are part of the normal human microbiota. However, in recent years, nosocomial bloodstream Candida infections have emerged as a significant problem ranking the fourth common cause of fungemia in intensive care units. Although microdilution methods are the ones recommended for susceptibility testing, they are difficult to undertake in the clinical practice. Thus, an automated commercially available test is ideal. Aims. To compare minimum inhibitory concentrations (MICs) obtained with the recently introduced Vitek 2 yeast susceptibility system card (AST-YS01) with Etest. Methods. 263 clinical Candida isolates representing six species were included in the study. Categorical agreements (CA) were assessed as described elsewhere. Results. Irrespective of the Candida species tested, the overall CA between Vitek 2 and Etest ranged between 66.7% and 100%. In general, Etest yielded lower MICs than Vitek 2. For Candida albicans, the CA between Vitek 2 and Etest was >95% for amphotericin B, voriconazole and flucytosine, but only 89% for fluconazole. With respect to Candida glabrata, the CA was between 97% and 100%. The major errors were with Candida krusei and flucytosine and Candida kefyr and amphotericin B. Candida tropicalis susceptibility for fluconazole by Vitek 2 reported more SDD and resistant strains than Etest. Candida parapsilosis showed 100% CA against all the four antifungals tested. No very major errors were detected between the two methods. Conclusions. Vitek 2 provided comparable results to Etest with quick turnaround for the testing of Candida species susceptibilities (AU)

Antecedentes. Candida forma parte de la microbiota habitual del ser humano. Sin embargo, en los últimos años, las candidemias hospitalarias se han convertido en un problema significativo en las unidades de cuidados intensivos al ocupar el cuarto lugar entre las fungemias. Puesto que los métodos de microdilución, recomendados para las pruebas de sensibilidad in vitro, son difíciles de realizar en la práctica clínica, las pruebas comerciales y automatizadas son las de uso ideal. Objetivos. Comparar las concentraciones mínimas inhibidoras (CMI) obtenidas por los métodos Vitek 2 (AST-YS01) y Etest. Métodos. Se utilizaron 263 cepas clínicas de Candida, pertenecientes a seis especies. Se evaluaron los acuerdos categóricos (AC) según lo ya descrito. Resultados. Con independencia de la especie de Candida, el AC general entre Vitek 2 y Etest osciló entre el 66,7 y el 100%. En general, Etest arrojó CMI más bajas que las de Vitek 2. Para Candida albicans el AC entre Vitek 2 y Etest fue > 95% con la anfotericina B, el voriconazol y la flucitosina, pero solo del 89% con el fluconazol. Con Candida glabrata el AC fue del 97-100%. Las mayores diferencias se registraron con Candida krusei y la flucitosina, y con Candida kefyr y la anfotericina B. Los valores de sensibilidad de Candida tropicalis con el fluconazol arrojaban más cepas SDD y resistentes con Vitek 2. El AC con Candida parapsilosis fue del 100% con todos los antifúngicos testados. No se observaron grandes diferencias entre los dos métodos. Conclusiones. Vitek 2 proporciona resultados comparables con los de Etest, con un tiempo rápido de respuesta respecto a las especies de Candida susceptibilidad (AU)

Comparison of the VITEK 2 antifungal susceptibility system with Etest using clinical isolates of Candida species.

BACKGROUND: Candida species are part of the normal human microbiota. However, in recent years, nosocomial bloodstream Candida infections have emerged as a significant problem ranking the fourth common cause of fungemia in intensive care units. Although microdilution methods are the ones recommended for susceptibility testing, they are difficult to undertake in the clinical practice. Thus, an automated commercially available test is ideal. AIMS: To compare minimum inhibitory concentrations (MICs) obtained with the recently introduced Vitek 2 yeast susceptibility system card (AST-YS01) with Etest. METHODS: 263 clinical Candida isolates representing six species were included in the study. Categorical agreements (CA) were assessed as described elsewhere. RESULTS: Irrespective of the Candida species tested, the overall CA between Vitek 2 and Etest ranged between 66.7% and 100%. In general, Etest yielded lower MICs than Vitek 2. For Candida albicans, the CA between Vitek 2 and Etest was >95% for amphotericin B, voriconazole and flucytosine, but only 89% for fluconazole. With respect to Candida glabrata, the CA was between 97% and 100%. The major errors were with Candida krusei and flucytosine and Candida kefyr and amphotericin B. Candida tropicalis susceptibility for fluconazole by Vitek 2 reported more SDD and resistant strains than Etest. Candida parapsilosis showed 100% CA against all the four antifungals tested. No very major errors were detected between the two methods. CONCLUSIONS: Vitek 2 provided comparable results to Etest with quick turnaround for the testing of Candida species susceptibilities.