Direct Fluconazole Disk Susceptibility Testing for Candida glabrata-Positive Blood Cultures

Direct susceptibility testing from blood cultures has been reported to reduce the time interval between a positive blood culture to preliminary reporting of susceptibility and can underpin timely appropriate treatment of candidemia. The aim of this study was to evaluate direct susceptibility testing of Candida glabrata to fluconazole using disk diffusion compared to the Sensititre YeastOne broth microdilution-based method. We tested 83 isolates recovered from 93 spiked and prospective blood culture bottles. Comparison of the two methods showed excellent agreement, with no very major errors and only two major errors (2.4%). The accuracy of the fluconazole disk method was 97.6% (95% confidence interval [CI], 91.6 to 99.7), with a sensitivity of 100% (95% CI, 82.3 to 100) and a specificity of 96.9% (95% CI, 89.2 to 99.6). Direct antifungal disk susceptibility testing from blood cultures is a rapid and easy-to-perform method to determine fluconazole susceptibility of C. glabrata isolates and can be used safely to reduce susceptibility report time and improve clinical decision making regarding appropriate treatment.