Bacterial screening of platelet concentrates: results of 2 years active surveillance of transfused positive cultured units released as negative to date

BACKGROUND: The BacT/ALERT system for bacterial monitoring of platelet concentrates (PCs) was introduced in the Netherlands in 2001. Samples are cultured for 7 days, and as a result of the short shelf-life of PCs, they are usually released as 'negative to date'. Therefore, some of the PCs have already been transfused at the moment of a positive signal in continued cultures in the BacT/Alert. It is unclear, however, whether these PCs are associated with more transfusion reactions. METHODS: During a 2-year period clinical data were collected from all patients who received PCs released as 'negative to date' but with a positive bacterial culture after being transfused. RESULTS: Data of 158 patients who received PCs with confirmed positive bacterial culture tests were analysed. Two patients developed a transfusion reaction. In both PCs, Propionibacterium was cultured. The imputability as related to the transfusion was classified as unlikely in both patients. CONCLUSION: Two of 158 transfusions of PCs released as 'negative to date', but with a confirmed positive BacT/ALERT result, were initially associated with transfusion reactions. However, the imputability of both reactions was low.