AN EVALUATION OF 7 METHODS OF IN-VITRO SU SCEPTIBILITY TESTING OF CLINICAL YEAST ISOLATES AGAINST FLUCONAZOLE

Four commercially available in vitro test systems (Candifast(R), E-tes t, Mycototal(R), Spiral-Gradient Endpoint Method), agardiffusion with 25 mu g fluconazole paper test discs and 15 mu g test tablets, and aga rdilution were compared to the microbroth dilution method by fluconazo le susceptibility testing of 145 clinical isolates. In addition, the c ulture media provided or recommended by the manufacturers of the test systems were compared to the high resolution (HR) antifungal test medi um. With all currently available culture media growth problems (inhibi tion or delayed growth of the clinical isolates) occurred with solid o r semi-solid media. With minor improvements, HR medium demonstrated th e most reproducible and comparable results (supplementation with aspar agine and deletion of sodium hydrogen carbonate). Best correlation to microdilution was obtained by the agardilution method (> 95% concordan ce) followed by the spiral-gradient endpoint method (85%), Candifast(R ) (83%), Mycototal(R) (81%) and the E-test (78%). Regression analysis demonstrated good correlation between agardiffusion and micro-/agardil ution (r > 0.9).