Blood surveillance and detection on platelet bacterial contamination associated with septic events.

The objective of this study was to evaluate the risk of transfusion-associated septic events in Taiwan. In Taiwan, most blood components are provided from blood centres; so platelet (PLT) bacterial contaminations are rarely reported. The study's aim is to investigate the prevalence of PLT bacterial contamination in Kaoshiung Armed Forces General Hospital by using BacT/ALERT system for routine screening. A total of 82 apheresis and 2256 whole blood-derived PLT units were tested. A measured quantity of 1 mL aliquots were taken as samplings from all blood bag tubing of PLT units, and then further incubated in a bacterial detection system (BacT/ALERT). The subcultures of true-positive bottles underwent bacterial identification by using Vitek system, microscopic observation and culture-based methods. Eight units (0.34%, 8 of 2338) were found to have bacterial contamination. The true-positive rate of the whole blood-derived and apheresis PLTs was 0.31% (7 of 2256) and 1.22% (1 of 82), respectively. Six microorganisms were identified with the most dominate being Staphylococcus epidermidis. One case of transfusion-associated sepsis was confirmed; in addition, the holding period of PLTs (F = 4.522, P = 0.034) and positive detection of PLT bacterial contamination (F = 46.605,P < 0.001) were associated with post-transfusion sepsis. Thus, in this study, although the transfusion-associated septic event was rarely found and PLT units were provided from blood centres, bacterial screening was necessary to safely quarantine the transfusion. The holding period of PLT units should be no more than 4 days in order to avoid possible bacterial contamination.