Effects of yeast on automated cell counting.

We studied the effects of yeast in peripheral blood samples on results reported by an ADVIA 120/2120 Hematology System (Bayer HealthCare, Diagnostics Division, Tarrytown, NY). In a simulated candidemia model, very high concentrations (1-5 x 10(8) colony-forming units [CFU]/mL) of Candida glabrata and Candida parapsilosis caused a spuriously elevated platelet count. No such effect was observed with Candida albicans. All 3 yeast species, when present at a concentration of 1-5 x 10(6) CFU/mL or greater, increased the automated WBC counts significantly and in a dose-dependent manner. The yeast cells were mainly misidentified as lymphocytes. All spurious results were flagged by the cell counter for microscopic review. We conclude that although the presence of yeast in a blood sample can interfere with the ADVIA 120/2120 Hematology System, compromised results are appropriately flagged by the instrument and are seen only when the yeast concentration is very high.