Abstract for One Cell Systems Poster:

An alarming increase in fungal infections has underscored the need to improve current drug susceptibility assays. Combining Gel microdrop (GMD) technology and flow cytometry, we developed a rapid fungal susceptibility assay to determine the minimum inhibitory concentration (MIC) of anti-fungal agents for the clinic isolates and to identify the existence of resistant population. In this assay, yeast cells were individually encapsulated in 35-50 mm agarose microspheres. After 4-6 hrs incubation, micro-colonies were observed virtually in all occupied GMDs. GMDs were then fixed by 70% ethanol and stained with propidium iodide (PI). The increase of PI fluorescence intensity was measure by flow cytometry to indicate cell growth. Compared to 48-hrs assay time in conventional microdilution methods, MIC could be obtained in as little as 6-8 hrs with this assay. The obtained MICs from this GMD assay correlated well with those from conventional microdilution methods. These susceptibility results were further confirmed in the test using clinic isolates. In addition, a 0.28% drug resistant sub-population was identified using fluorescence activating cell scanner (FACScan).