Microbial contamination detection methods in platelet concentrates

Background and ObjectivesBacterial contamination of blood products, especially platelets, may lead to bacterial sepsis or death and therefore is of concern. Many techniques have been explored to detect bacteria in blood products in order to prevent transfusion-related bacteria contamination and transmission. In the present study, four different methods were employed to detect 12 platelet units precontaminated with known bacteria.Materials and MethodsTen units of platelet concentrates were inoculated at three levels (150, 15, and 1.5 CFU per ml) with Escherichia coli and Staphyococcus epidermidis. All of the platelet concentrates and two control units of platelet concentrates were stored at 20 to 24 ° C for five days. Every morning during storage, platelet concentrates were tested for platelet pH, plasma glucose, quantitative plate culture, and gram staining on platelet centrifuged smears. ResultsEscherichia coli with 150 and 15 CFU per ml and staphylococcus epidermidis with 150 CFU per ml grew on culture medias after two days but staphylococcus epidermidis with 15 CFU per ml did after three days. The sensitivity rate of bacteria detection in platelet concentrates through gram staining was lower than quantitative culture. Despite lower plasma glucose level in platelet concentrates (as measured by hexokinase enzymatic method) inoculated with microbial staines, pH level in platelet concentrates (as measured by pH meter) contentiously increased during five days of storage. ConclusionsThe sensitivity rate of bacterial detection in platelet concentrates through measuring extra cellular pH was estimated to be higher than that of plasma glucose, culture and gram staining methods.