SEROLOGY OF CAMPYLOBACTER-FETUS SS-JEJUNI .2. SEROTYPING OF LIVE BACTERIA BY SLIDE, LATEX AND CO-AGGLUTINATION TESTS

Abstract

Antisera against 12 Campylobacter strains (8 C. fetus ssp. jejuni, 2 C. fetus ssp. fetus and 2 C. fetus ssp. intestinalis) were obtained from rabbits immunized with formalin treated bacteria. Cross testing of live, boiled and autoclaved organisms of these strains were performed with direct slide and tube agglutinations and with agglutinations of latex particles and protein A-containing staphylococci coated with antibodies. Absorption experiments confirmed that both heat labile and heat stable antigens were present. The highest specificity for serological differentiation was obtained when slide and latex agglutination tests were used with live bacteria. These tests were subsequently used for differentiation of C. fetus ssp. jejuni strains, employing 22 C. fetus ssp. jejuni antisera absorbed with boiled homologous bacteria. Clear-cut homologous reactions, with few and weak cross reactions, indicated the presence of a variety of heat labile antigens, which could form a basis for serotyping. Preliminary typing of 170 clinical isolates with slide agglutination using 17 unabsorbed C. fetus ssp. jejuni antisera demonstrated the applicability of this approach for epidemiological studies. Serotyping revealed the presence of antigenically similar strains in family outbreaks, antigenic differences in strains of different origin, new combinations of cross reactions not seen in strains used in immunizations, antigenically new strains not reacting with these antisera and the dominance of a few antigenic types among the isolates.