Correlation between broth microdilution, E-test and disk diffusion methods for testing antifungal susceptibility of Candida species isolated from Thai blood samples
Article Category: Brief communication (Original)
Published Online: Jan 31, 2017
Page range: 75 - 80
DOI: https://doi.org/10.5372/1905-7415.1001.468
Keywords
© 2016 Veeravich Jaruvongvanich, Navaporn Worasilchai, Kitravee Kongnatthasate, Suthinee Jaruvongvanich, Wilawan Damkerngsuntorn, Dusita Atikarnbodee, Arsa Thammahong, Sansanee Lerdlitruangsin, Ariya Chindamporn, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Background
Broth microdilution (BMD) is a standard assay for susceptibility of Candida to antifungals, but complexity limits its routine application. E-test (ET) and disk diffusion (DD) assays are attractive alternatives because of their simplicity and reproducibility.
Objectives
To determine the correlation between BMD, and ET and DD assay results for Candida isolates.
Methods
We tested 63 Candida isolates for their susceptibility to fluconazole and voriconazole using BMD, ET, and DD, and recorded minimum inhibitory concentrations (MIC) and inhibitory zone diameters (ZD). Spearman correlations were determined and the Clinical and Laboratory Standards Institute recommendations were used to assess major and minor errors in test results.
Results
The isolates included 32 (51%) C. albicans, 14 (22%) C. tropicalis, 12 (19%) C. parapsilosis, 4 (6%) C. glabrata, and 1 (2%) C. guilliermondii. The BMD-MIC and ET-MIC had good correlation for fluconazole (r = 0.94; P < 0.001) and voriconazole (r = 0.95; P < 0.001). The BMD-MIC for both antifungals were significantly correlated with the ZD of the DD assays (r = −0.47; P < 0.001; r = −0.75; P < 0.001, respectively). Agreement between the BMD and the ET and DD results exceeded 90%. No major errors were identified in any comparisons.