Detection of bacteria in WBC‐reduced PLT concentrates using percent oxygen as a marker for bacteria growth

Abstract

BACKGROUND: The risk of receiving a PLT concentrate (PC) contaminated with bacteria may be 1000‐fold greater than that of pathogenic viral transmission, yet surveillance for this risk is not generally practiced. A novel bacteria detection system (BDS) that overcomes the limitations of current systems is described. The BDS monitors percent oxygen (%O 2 ) in air above aliquots of PCs that have been filtered to remove the confounding effect of respiring PLTs and residual WBCs. STUDY DESIGN AND METHODS: One‐day‐old WBC‐reduced whole‐blood‐derived PCs (WBPCs) were inoculated with bacteria at 100 to 500 CFU per mL. After 30 minutes, 2‐ to 3‐mL aliquots were processed through a PLT‐reducing filter into a sample pouch containing sodium polyanethol sulfonate and entrained air. After incubation at 35°C for at least 24 hours, the %O 2 was measured within the pouch. Noninoculated WBC‐reduced WBPCs (n = 155), confirmed free of bacteria by routine culture, were tested in a like manner. Results from the latter group of WBC‐reduced WBPCs were used to distinguish contaminated from noncontaminated units. RESULTS: After a 24‐hour incubation at 35°C, 195 (96.5%) of the 202 sample pouches obtained from inoculated units were detected by the BDS. After an additional 6 hours at room temperature, those that remained and were tested were found positive. None of the noninoculated controls produced a positive reading. CONCLUSION: The BDS is easy to use and provides good levels of sensitivity and specificity.