Immunochemical analysis of the extracellular slime substance ofStaphylococcus epidermidis

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Abstract
To analyze immunochemically the extracellular slime substance ofStaphylococcus epidermidis, rabbits were repeatedly immunized with the crude slime extract isolated from an adherent, slime-producing clinicalStaphylococcus epidermidis strain. Immunoelectron microscopy demonstrated that the target antigens of the resulting antibodies were located in the extracellular slime-like layer of bacterial cells. When these target antigens were characterized by immunoblotting, a variety of antigens were detected, including many with molecular masses higher than 80 kilodaltons and also a predominant one with a molecular mass of 30 kilodaltons. No characteristic differences were observed between the tube adherence test positive and negativeStaphylococcus epidermidis isolates. Although there was variation in the number and intensity of high molecular mass antigens, such variations did not correlate with the tube adherence test. Of the 110Staphylococcus epidermidis isolates studied, 106 (96 %) expressed the 30-kilodalton antigen. This component was found in no otherStaphylococcus spp. examined in the study. The bacterial component was not only easily detached from bacterial cells but also watersoluble, characteristics implicating a slime-like nature. Further studies are needed to definitively establish the origin and nature of the 30-kilodaltonStaphylococcus epidermidis-specific component, and determine its potential benefit as a diagnostic tool.