Abstract

BALLESTE, Raquel et al. Evaluación del desempeño diagnóstico del medio de difusión en agar Etest® para el estudio de sensibilidad a los antifúngicos. Rev. Méd. Urug. [online]. 2006, vol.22, n.2, pp.128-135. ISSN 1688-0390.

Summary The increase of the incidence of mycosis has led to develop new techniques to study in vitro antifungal susceptibility. In this study, Agar Etest –the most used method of agar dilution in our country– was compared to the reference method –broth microdilution method– and the MICs for both techniques were correlated. Eighty Candida spp. strains were studied using Etest and broth microdilution method (Protocol M27-A2 del National Committee for Clinical Laboratory Standards [NCCLS]). Amphotericin B (AB), itraconazol (ITZ) and fluconazole (FLZ) were tested. Etest diagnostic performance was compared to the reference method (EPIDAT, version 2.0 for Windows); correlation was calculated using Pearson’s correlation coefficients. Etest specificity and sensitivity for ITZ were 44% and 92% respectively, positive predictive value (VPP) was 60% and negative predictive value (VPN) 85%. Specificity and sensitivity for FLZ were 85% and 12.5% respectively, VPP was 45% and VPN 49%. For AB, Etest did not detect resistant strains. Predictive values were calculated to detect resistance using NCCLS breakpoints. correlation coefficients were as follow: r = - 0,02 (AB), r = - 0,03 (FLZ) y r = 0,4 (ITZ). The method was not validated since there was no correlation between MICs obtained by Etest and those obtained by the reference technique. According to the findings, diagnostic performance of the technique was not reliable. Global performance of Etest seems to be unreliable for clinical tests.

Keywords : RESISTENCIA A DROGAS ANTIFÚNGICAS; AGAR [uso diagnóstico]; INMUNODIFUSIÓN [métodos]; TESTS DE SENSIBILIDAD MICROBIANA [métodos].

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