Applications of fluorescent antibody for detecting capsular substances in Staphylococcus epidermidis.

Abstract

A fluorescent antibody technique was developed for the determination of the type of capsule of strains of Staphylococcus epidermidis. Many mouse virulent and avirulent strain populations were investigated. Of 300 fresh isolates of Staph. epidermidis, 27 were mouse virulent strains and of these 74.1% and 25.9% were mono- and polyvalent, respectively. The frequency of capsular type antigens I, II and III, produced by the 27 virulent strains was found to be 18.5%, 88.9% and 18.5%, the majority being capsular type II. In the mouse avirulent strains, capsular type antigen production was demonstrated in 263 out of 273 strains examined and mono- and polyvalent capsular types comprised 52.3% and 44.0%, respectively. Capsular type I, II, III strains and non-typable strains occurred at frequencies of 15.0%, 95.2%, 34.9% and 3.7% respectively, the majority of mouse avirulent strains also being capsular type II. These results indicate that a majority of ordinary Staph. epidermidis produced capsular type antigens although the capability is quantitatively different according to strain.