Abstract: Objective To develop a rapid method for estimating the activity of antifungal drug by flow cytometry (FCM). Methods Referring to M27-A the minimum inhibitory concentration (MIC) of 21 Candida isolates to fluconazole (FCZ) was detected. The samples were incubated with FCZ in different concentrations for 3 hrs. Then they were stained by a membrane-impermeable fluorochrome, prepidium iodide (PI), for 0.5 h. According to the fluorescence intensity of different drug concentrations, MIC was defined as the lowest drug concentration in which the mean fluorescence intensity was 60% higher than that in the active growth control. Results The MIC detected by flow cytometry susceptibility testing (FCST) ranged from 0.125 to 64 μg/mL and the MIC of M27-A ranged from 0.25 to 0.64 μg/mL, there was no significant difference in MIC between FCST and M27-A (P>0.05). In this study MIC result could be detected by FCST within 4 hrs. Conclusion FCST is a rapid, accurate and sensitive methed for Candida MIC determination.

Key words: Flow cytometry, Candida, Fluconazole, Microbial sensitivity tests