Transfusion-Associated Bacterial Sepsis

Transfusion-associated bacterial sepsis (TABS) is caused by bacteria present in blood components. It is one of the earliest recognized adverse transfusion-associated reactions. Blood components most often become contaminated while blood is being collected from a donor; more seldom in the case of asymptomatic bacteremia or erroneous blood processing procedures (1). Although the risk for transfusion-associated bacterial sepsis has diminished considerably since the introduction of new methods of bacteria detection and of increasingly better means of skin disinfection, reappearing reports about severe or fatal reactions after contaminated blood component transfusions prove that the problem is still very serious. Most often bacterial contamination affects red blood cell concentrates and platelet concentrates. There have been cases reported of bacterially contaminated plasma or cryoprecipitate, although bacteria do not proliferate in these components when they are stored (1,2). Of note, bacterial sepsis is an adverse reaction not only after allogenic transfusions but also after autologous ones. Bacteria are very rarely transmitted during blood component transfusion, but if they are, they usually cause severe, life-threatening adverse reactions, with the mortality rate of 20 – 30%. In USA, bacteria transmission during transfusion is the second (just after “administrative error”) most common cause of fatal transfusion-associated reactions. It is estimated that every year 100 – 150 patients undergoing blood component transfusion die because of that (1). This number is probably underestimated. There are a few causes of this situation. Tests which can confirm or exclude the infectious background of adverse reactions occurring during or right after transfusion are not always performed. Besides, the organism’s response to infection may be misinterpreted as a manifestation of the underlying disease or another non-infectious transfusion-associated reaction. That is why the estimated prevalence of fatal adverse reactions may be overestimated because the adverse reactions that have the most severe course are predominantly reported to the relevant registering centers. The risk for transfusion-associated bacterial sepsis results from the nature of pathogens themselves and from determinants connected with blood donors and recipients. From the transfusiology point of view, the characteristic features of infectious agents include their biology, the course of infection, the degree of infectivity, and how harmful they are for the recipient if transfusion-associated bacterial infection occurs. The crucial issues are whether: • An infectious agent is present in blood in the course of infection, how long it has been there, at what concentration;