Rapid identification of Candida albicans in blood by combined capillary electrophoresis and fluorescence in situ hybridization

A CE method based on whole-cell molecular labeling via fluorescence in situ hybridization was developed for the detection of Candida albicans in whole blood. Removal of potentially interfering red blood cells (RBC) with a simple hypotonic/detergent lysis step enabled us to detect and quantitate contaminating C. albicans cells at concentrations that were orders of magnitude lower than background RBC counts (similar to 7.0 x 10(9) RBC/mL). In the presence of the lysed blood matrix, yeast cells aggregated without the use of a blocking plug to stack the cells. Short (15 min) hybridizations yielded bright Candida-specific fluorescence in situ hybridization signals, enabling us to detect as few as a single injected cell. The peak area response of the stacked Candida cells showed a strong linear correlation with cell concentrations determined by plate counts, up to similar to 10(7) CFU/mL (or similar to 1 x 10(4) injected cells). This rapid and quantitative method for detecting Candida in blood may have advantageous applications in both human and veterinary diagnostics.