Immunoreactivity of 80-kDa peptidoglycan and teichoic acid-like substance of slime producing S-epidermidis and specificity of their antibodies studied by an enzyme immunoassay

S. epidermidis is considered an important cause of nosocomial bacteraernia in immunocompromized hosts as well as the commonest agent of sepsis in pati ents with prosthetic devices. Pathogenesis is attributed to adherence and g rowth on bioniaterials facilitated by production of extracellular slime. Th e major macromolecules of slime are: a 20-kDa acidic polysaccharide (20-kDa PS) comprising the 60% of carbohydrate-containing slime macromolecules, a peptidoglycan with average molecular size of 80-kDa (30% of slime dry weigh t) and cell wall teichoic acid-like substance. In this study, antibodies to these macromolecules as well as crude slime were raised in rabbits and the ir immunological reactivity and specificity were studied by an enzyme immun oassay. All isolated macromolecules induced the production of specific anti bodies. 20-kDa PS was less immunogenic than 80-kDa peptidoglycan and teicho ic acid-like substance. However, 20-kDa PS was the most potent inhibitor of the reaction of slime with its homologous antibodies revealing that this p olysaccharide is the major antigenic determinant of slime. All three antibo dies specifically recognize (p < 0.05) and react with slime-producing S. ep idermidis in comparison to other staphylococci species. Obtained results in dicate that the 20-kDa PS may be distributed in the surface of the slime ex posing most of its antigenic determinants to the immune system, whereas tho se of 80-kDa peptidoglycan and teichoic acid-like substance seem to be less accessible. (C) 2001 Elsevier Science B.V. All rights reserved.