A 140-KILODALTON EXTRACELLULAR PROTEIN IS ESSENTIAL FOR THE ACCUMULATION OF STAPHYLOCOCCUS-EPIDERMIDIS STRAINS ON SURFACES

Two distinct pathogenic mechanisms, adhesion to polymer surfaces and s ubsequent accumulation of sessile bacterial cells, are considered impo rtant pathogenic steps in foreign body infections caused by Staphyloco ccus epidermidis, By using mitomycin mutagenesis, we have recently gen erated a mutant, strain M7, from S. epidermidis RP62A which is unaffec ted in adhesion but deficient in accumulation on glass or polystyrene surfaces and lacks a 115-kDa extracellular protein (designated the 140 -kDa antigen; F. Schumacher-Perdreau, C. Heilmann, G. Peters, F. Gotz, and G. Pulverer, FEMS Microbiol. Lett. 117:71-78, 1994), To evaluate the role of this protein in accumulation, we harvested extracellular p roteins from S. epidermidis RP62A grown on dialysis membranes placed o ver chemically defined medium, purified the protein by using ion-excha nge chromatography, determined its N-terminal amino acid sequence, and raised antiserum in rabbits, The antibody recognized only a single ba nd in a Western immunoblot of the crude extracellular extract, With th e microtiter biofilm test, antiserum at a dilution of less than or equ al to 1:1,000 blocked accumulation of RP62A up to 98% whereas preimmun e serum did not, The 140-kDa antigen was found only in extracellular p roducts from bacteria grown under sessile conditions, Of 58 coagulase- negative clinical isolates, 32 strains were 140-kDa antigen positive a nd produced significantly larger amounts of biofilm than the 26 strain s that were 140-kDa antigen negative, The 140-kDa protein appears to b e biochemically and functionally unrelated to any previously described factors associated with biofilm formation, Thus, the 140-kDa antigen, referred to as accumulation-associated protein, may be a factor essen tial in S. epidermidis accumulation and, due to its immunogenicity, ma y allow the development of novel immunotherapeutic strategies for prev ention of foreign body infection.