Detection and Quantitation of Bacteria in Platelet Products Stored at Ambient Temperature

Abstract

A study of bacterial contamination in platelet products stored at ambient temperature demonstrated the presence of bacteria in 2.4 per cent of platelets as determined by culturing platelet pools. The recovery of bacteria increased as storage time prior to culture increased, which suggested bacterial proliferation during storage. While many of the bacteria recovered were normal skin flora, i.e ., diphtheroids and Staphylococcus epidermidis , pathogens such as Enterobacter cloacae, Staphylococcus aureus , and Pseudomonas spp. were recovered several times. Quantitative cultures were performed in the present study which demonstrated that most pools contained relatively few microorganisms, although some harbored more than 500 bacteria/ml after ambient temperature storage. The introduction of microorganisms during the pooling procedure can not be ruled out. Of 3,251 units not subjected to pooling, 45 (1.4%) were found to contain bacteria. Platelets kept at ambient temperature for 11 to 71 days were cultured and 38 of 631 (6.0%) individual units contained bacteria. Four additional severe patient reactions and two deaths have occurred consequent to transfusion of platelets contaminated with bacteria. These observations lead to the conclusion that caution should be exercised in the use of platelets stored at ambient temperature.