Evaluation of an Automated Urine Flow Cytometer for Screening of Bacterial Contamination in Platelet Concentrates

ABSTRACT

BACKGROUND: Bacterial contamination of blood products, particularly of platelet concentrates (PCs), is a major risk factor for infections caused by blood transfusion. Various methods for the detection of bacterial contamination in PCs are available or are under investigation. We evaluated the usefulness of the Sysmex UF-1000i urine flow cytometer (Sysmex Medical Electronics Co, Japan) for screening of bacterial contamination in PCs. METHODS: The PCs were inoculated with various concentrations of bacteria (Staphylococcus aureus and Escherichia coli) and were analyzed with the urine flow cytometer for bacterial counts. All the samples were diluted with normal saline (110) before flow cytometric analysis in order to prevent interference by the turbidity due to platelets. RESULTS: For PCs inoculated with a high number (colony forming unit, CFU) of bacteria (105 CFU/mL), the bacterial counts were significantly higher than those for uninoculated PCs analyzed by the urine flow cytometer. However, bacterial counts for PCs inoculated with bacteria of 104 CFU/mL or less and those for uninoculated PCs were not significantly different. CONCLUSIONS: An automated urine flow cytometer evaluated in this study is easy to use, and the procedure is completed in less than 5 min. Moreover, the urine flow cytometer could detect approximately 105 CFU/mL of bacteria in PCs. Further validation studies are needed to assess the usefulness of this method for screening of bacterial contamination in PCs.