How do I investigate septic transfusion reactions and blood donors with culture-positive platelet donations?

I n the early 1990s, bacterial contamination of blood components was recognized as the most common cause of transfusion-transmitted infection, accounting for between 14 and 24% of transfusion associated fatalities reported to the US Food and Drug Administration and various hemovigilance systems. Because platelets (PLTs) are stored at room temperature, they provide a hospitable environment for the growth of many bacterial organisms and are most often involved in septic transfusion reactions. Many measures have been taken to prevent bacterial contamination, including verifying the donors’ temperature and questioning them about infection, optimizing skin disinfection before phlebotomy, and diverting the initial aliquot of blood collected during the procedure. Blood centers have also introduced methods to detect contamination, such as culturing PLT donations and visually inspecting components before the transfusion. Indeed, since the 22nd edition in 2003, the AABB Standards for blood banks and transfusion services state that the blood bank and transfusion service shall have methods to limit and detect bacterial contamination in all PLT components. These measures have reduced but have not completely eliminated the risk of septic transfusion reactions. Prompt investigation of suspected septic transfusion reactions is essential not only to provide appropriate care for the affected patient, but also to prevent transfusion of other bacterially contaminated cocomponents from the same donation. For whole blood–derived PLTs, associated red blood cell (RBC) units and occasionally frozen plasma units have been found to be contaminated as well as the PLT component from a donor. For apheresis units, double and triple PLT collections are increasingly common and there have been several reports of contamination of all apheresis components from the same donation. In addition, the involved donors, and steps in the component preparation process, are evaluated to assess the possible source of bacterial contamination. Although the vast majority of bacterial isolates implicated in septic transfusion reactions are organisms that are part of normal skin flora, in rare cases, bacteria isolated in the context of a septic transfusion reaction may have implications relevant to the donors’ health. Moreover, blood centers evaluate the information to assess these donors’ continued eligibility to donate blood for transfusion to others. As with other major adverse transfusion reactions, the identification, investigation, and reporting of these reactions to the hemovigilance scheme are important to evaluate the extent of the problem and the efficacy of preventive measures that may have been introduced.