Effect of prestorage white cell reduction on bacterial growth in platelet concentrates

Platelet concentrates stored with and without autologous white cells were produced from units of whole blood that had been purposefully contaminated with bacteria immediately after phlebotomy. The blood was inoculated with one of five species of bacterium at either 10 or 50 colony-forming units per mL. The growth of the organisms was quantified throughout the conventional 5-day, 22°C storage period of the platelet concentrates. One species, Klebsiella pneumoniae, failed to grow in any of the components. The remaining species, Staphylococcus epidermidis, S. aureus, Enterococcus faecalis, and Salmonella enteritidis, achieved log growth after 1 day of storage and reached a relative maximum concentration by Day 3. Although the concentration of bacteria immediately after inoculation was lower in the units reduced in white cells by filtration, no significant differences were observed thereafter. Data from this in vitro study support the concept that prestorage white cell reduction of platelet concentrates should not increase the likelihood of transfusion-induced septicemia.