O-antigenic specificity of lipopolysaccharides from Bacteroides fragilis ss. fragilis.

Lipopolysaccharides (LPS) isolated from three strains of Bacteroides fragilis ss. fragilis were examined by indirect haemagglutination and inhibition of haemagglutination in unabsorbed and absorbed rabbit antisera. Six different antigenic specificities were detected. All serological activity was destroyed by oxidation of LPS with periodate.