Abstracts

Objective: This study compared the efficacy of bacterial screening using a culture method (BacT/Alert System, Biomerieux) with pathogen inactivation (INTERCEPT Blood System, Baxter Healthcare) to prevent the transfusion of platelet components contaminated with bacteria.

Methods: Seven strains of bacteria associated with transfusion-associated sepsis, including Gram-positive, Gram-negative and the anaerobes were studied. Paired (Control and Test) platelet concentrates (PC) containing approximately 3 x10E11 platelets in 300 mL of 35% plasma and 65% InterSol® were contaminated with each strain of bacteria at 10, 100, and 1,000 cfu per unit. After an overnight storage, the Test PC was treated with INTERCEPT (150 µM amotosalen and 3 J/sq cm UVA). The Control PC was not treated. Both units were assayed for aerobic and anaerobic bacteria using the BacT/Alert System at the time of bacterial inoculation and on days 1, 2 and 5 of storage. A platelet sample was considered contaminated with bacteria if a positive signal was registered within 120 hrs of culture.

Results: For Control PC, cultures failed to detect low-dose inocula (Table 1). In contrast, all Test PC treated with INTERCEPT remained negative by BacT/Alert cultures throughout the entire 5-day observation period regardless of the strain and the contamination level.

Conclusions: Bacterial detection using cultures may fail to detect low levels of bacteria. Failure to detect bacteria will result in the release of contaminated platelet products with “test negative-to-date” status. In contrast, inactivation of bacteria is capable of preventing release of contaminated platelet components.

Key words: Bacterial screening; bacterial inactivation; amotosalen; UVA