The Impact of Bacterial Biofilms in Transfusion Medicine

Abstract

Blood transfusion is a life-saving practice that started in the early 1800s. Blood components used for transfusion therapy for bleeding patients include platelet concentrates (PCs), red cell concentrates, and plasma. PCs are highly susceptible to bacterial contamination, due to their storage conditions in a nutrient-rich environment at ambient temperature, posing the most significant post-transfusion infectious risk. The predominant bacteria present in PCs are commensal inhabitants of the human skin such as Staphylococcus epidermidis (S. epidermidis) which are likely introduced at the time of blood collection. S. epidermidis and other common PC contaminants form surface-attached communities of matrix-embedded cells, known as biofilms, during PC storage. Biofilms are formed by bacteria adhering to either platelet cells or to the plastic of PC containers. Bacterial adhesion to PC containers is enhanced by the presence of plasma factors and can be reduced by physical or chemical modification of the PC storage bag. Biofilm formation can also be reduced by preventing platelet–bacteria interactions or by reducing the plasma content in PCs. The PC storage environment promotes biofilm formation by coagulase-negative staphylococci isolates traditionally considered to be biofilm negative, resulting in increased pathogenicity and missed detection during PC screening using automated culture systems. Recent studies have shown that the PC storage environment induces structural changes in the bacterial cell wall and biofilm matrix of S. epidermidis that could be responsible for resistance to immune clearance and persistent growth in this environment. Further studies are needed to deepen our understanding of the PC storage parameters responsible for triggering bacterial biofilm formation and to develop new strategies to improve PC safety for the benefit of transfusion patients.