Essential functional role of the polysaccharide intercellular adhesin of Staphylococcus epidermidis in hemagglutination

Hemagglutination of erythrocytes is a common property of Staphylococcus epi dermidis strains, which is related to adherence and biofilm formation and m ay be essential for the pathogenesis of biomaterial-associated infections c aused by S. epidermidis. In three independent biofilm-producing, hemaggluti nation-positive S. epidermidis isolates, interruption of the icaADBC operon essential for polysaccharide intercellular adhesin (PIA) synthesis by Tn91 7 insertions led to a hemagglutination-negative phenotype, An immunoglobuli n G fraction of antiserum to PIA greatly reduced hemagglutination. Purified PIA led to a 64-fold decrease of hemagglutination titers of these strains; however, it did not mediate hemagglutination by itself. These observations define PIA as the hemagglutinin of S. epidermidis or at least as its major functional component.