Bacterial contamination of red blood cell(RBC) or platelet concentrates occurs relatively infrequently, but has potentially fatal consequence when these products are transfused into patients. Red blood cells are stored for up to 42 days at 4 degrees C and are most frequently contaminated with bacteria that grow well at refrigeration temperatures(e.g.Yersinia enterocolitica,Pseudomonas fluorescens). In contrast, platelet concentrates stored for up to five days at room temperature (22-25 degrees C) to preserve function, are more frequently contaminated with gram positive organisms (e.g. Staphylococcus epidermidis, Staphylococcus aureus). Rapid, broad spectrum diagnostic tests for bacterial contamination that might be used to screen units prior to transfusion are lacking, as is knowledge of the true incidence rate of bacterial contamination of US blood products. A polymerase chain reaction(PCR)-based bacterial detection method has been developed for use with platelet concentrates, using primers directed towards conserved sequences with the 165rRNA genes found in all known prokaryotes. When bacterial contamination is detected, genus/species identification is achieved by direct DNA sequence analysis of the 165rRNA amplicon. The sensitivity of the method is being optimized for use in a survey of febrile reactions occurring during transfusion to quantify the frequency of, and the particular bacterial species most frequently involved in, bacterial contamination of platelet concentrates. This information will help FDA to identify risk factors (bacterial genetics, donor related, processing, storage, etc.)important for, and formulation of strategies to reduce, bacteremia and sepsis associated with transfusion of blood components.