Expression of biofilm-associated genes in Staphylococcus aureus during storage of platelet concentrates

Abstract

Background and objectivesIn transfusion medicine, the safety of platelet concentrates (PCs) is a major concern on account of contamination, mostly with Staphylococcus species. One of the most common contaminants is Staphylococcus aureus, which forms bacterial biofilms in PCs, posing a safety risk for transfusion patients. In this study, we investigate the contributions to biofilm formation of eno, ebps, and fib genes encoding surface proteins and of genes from the ica operon (icaA and icaD) encoding polysaccharide intercellular adhesin (PIA), along with their expression in bacteria grown in glucose-supplemented trypticase soy broth (TSBg) and PCs. Materials and methodsTwo strains of S. aureus (2039 and 2110) captured during routine PC screening were tested for biofilm formation in TSBg and under PC storage conditions, with mRNA collected at five time points and analyzed to determine expression of eno, ebps, fib, icaA, and icaD and their contributions to biofilm formation in both media. ResultsIn TSBg, S. aureus strain 2039 formed weak biofilms while 2110 formed strong. biofilms; however, in PCs, both strains formed strong biofilms. During biofilm formation, expression levels of icaA and icaD in both strains were generally significantly higher in TSBg than PCs. In contrast, expression of eno, ebps, and fib genes tended to be significantly higher under PC storage conditions. ConclusionThis study demonstrated that expression of genes involved in biofilm formation can be affected by growth media. Further investigation is needed to understand biofilm formation in the PC milieu and enhance transfusion safety.