Evaluation of two commercial methods for the susceptibility testing of Candida species: Vitek 2(R) and Sensititre YeastOne(R) / Evaluación de dos métodos comerciales para el estudio de la sensibilidad a los antifúngicos de especies de Candida: Vitek 2(R) y Sensititre YeastOne(R)

Background: An increased incidence of fungal infections caused by Candida species, especially Candida glabrata and Candida krusei, which are less susceptible to azoles, has been observed. Standardized susceptibility testing is essential for clinical management and for monitoring the epidemiology of resistance. Aims: We evaluated the performance of two different susceptibility testing commercial methods, Vitek 2(R) and Sensititre YeastOne(R), and compared them with the standard broth microdilution method (CLSI). Methods: A total of 80 isolates of several Candida species (Candida albicans, Candida parapsilosis complex, Candida tropicalis, C. glabrata and C. krusei) were selected for this study. Results: We analyzed the categorical agreement (CA) between the methods, stratifying the disagreements. The average CA between the methods was 96.3% for Vitek 2(R) and 84% for Sensititre YeastOne(R). No very major errors were observed. Major errors and minor errors were found for all the isolates tested. With the azoles, both Vitek 2(R) and Sensititre YeastOne(R) had good and similar performance levels, except for C. tropicalis and C. krusei (Sensititre YeastOne(R) showed low CA, 56.2%). With the echinocandins, both methods showed good performance for C. albicans, C. parapsilosis and C. tropicalis. However, we observed important discrepancies for C. krusei with caspofungin: Vitek 2(R) had 100% CA while Sensititre YeastOne(R) had only 25%. With amphotericin B, both Vitek 2(R) and Sensititre YeastOne(R) had good performance with high CA. Conclusions: Despite the limited isolates tested, we concluded that both methods have good performance and are reliable for antifungal susceptibility testing. However, caspofungin activity against C. krusei and C. glabrata should be interpreted carefully when using Sensititre YeastOne(R) because we observed a low CA

Antecedentes: La incidencia de infecciones fúngicas provocadas por especies de Candida, especialmente por Candida glabrata y Candida krusei, menos sensibles a los azoles, ha ido en aumento. Los métodos estandarizados de estudio de la sensibilidad a los antifúngicos son fundamentales para el manejo clínico y para un mejor seguimiento de la epidemiología de la resistencia. Objetivos: Se evaluó la actividad de dos métodos comerciales diferentes para el estudio de la sensibilidad in vitro a los antifúngicos, Vitek 2(R) y Sensititre YeastOne(R), y se compararon con la técnica estándar de microdilución en caldo del CLSI. Métodos: Para este estudio se seleccionó un total de 80 cepas aisladas de varias especies de Candida (Candida albicans, Candida parapsilosis, Candida tropicalis, C. glabrata y C. krusei). Resultados: Se analizó la concordancia categórica (CC) entre los métodos y se estratificaron los desacuerdos. La CC media entre los métodos fue del 96,3% para Vitek 2(R) y del 84% para Sensititre YeastOne(R). No se observaron errores muy altos. Se encontraron errores mayores y menores en todos los aislamientos probados. Con los azoles, tanto Vitek 2(R) como YeastOne(R) presentaron rendimientos buenos y similares, excepto para C. tropicalis y C. krusei (Sensititre YeastOne(R) mostró baja CC, el 56,2%). Con las equinocandinas, los dos métodos mostraron buen rendimiento para C. albicans, C. parapsilosis y C. tropicalis. Sin embargo, se observaron discrepancias importantes para C. krusei con la caspofungina: Vitek 2(R) presentó el 100% de CC, mientras que Sensititre YeastOne(R) solo el 25%. Para la anfotericina B, Vitek 2(R) y Sensititre YeastOne(R) presentaron un buen rendimiento con una CC alta. Conclusiones: Aunque el número de cepas aisladas probadas fue limitado, concluimos que los dos métodos tienen un buen rendimiento y son fiables para la prueba de sensibilidad antifúngica. Sin embargo, la actividad de la caspofungina frente a C. krusei y C. glabrata mediante el método Sensititre YeastOne(R) debe interpretarse cuidadosamente, ya que se observa un valor bajo de CC

Evaluation of two commercial methods for the susceptibility testing of Candida species: Vitek 2® and Sensititre YeastOne®.

BACKGROUND: An increased incidence of fungal infections caused by Candida species, especially Candida glabrata and Candida krusei, which are less susceptible to azoles, has been observed. Standardized susceptibility testing is essential for clinical management and for monitoring the epidemiology of resistance. AIMS: We evaluated the performance of two different susceptibility testing commercial methods, Vitek 2® and Sensititre YeastOne®, and compared them with the standard broth microdilution method (CLSI). METHODS: A total of 80 isolates of several Candida species (Candida albicans, Candida parapsilosis complex, Candida tropicalis, C. glabrata and C. krusei) were selected for this study. RESULTS: We analyzed the categorical agreement (CA) between the methods, stratifying the disagreements. The average CA between the methods was 96.3% for Vitek 2® and 84% for Sensititre YeastOne®. No very major errors were observed. Major errors and minor errors were found for all the isolates tested. With the azoles, both Vitek 2® and Sensititre YeastOne® had good and similar performance levels, except for C. tropicalis and C. krusei (Sensititre YeastOne® showed low CA, 56.2%). With the echinocandins, both methods showed good performance for C. albicans, C. parapsilosis and C. tropicalis. However, we observed important discrepancies for C. krusei with caspofungin: Vitek 2® had 100% CA while Sensititre YeastOne® had only 25%. With amphotericin B, both Vitek 2® and Sensititre YeastOne® had good performance with high CA. CONCLUSIONS: Despite the limited isolates tested, we concluded that both methods have good performance and are reliable for antifungal susceptibility testing. However, caspofungin activity against C. krusei and C. glabrata should be interpreted carefully when using Sensititre YeastOne® because we observed a low CA.