Serology of Campylobacter fetus ss. jejuni. 2 Serotyping of live bacteria by slide, latex and co-agglutination tests.

Antisera against 12 campylobacter strains (8 C. fetus ss. jejuni, 2 ss fetus and 2 ss. 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. Confirmed by absorption experiments both heat labile and heat stable antigens were demonstrated. The highest specificity for serological differentiation was obtained with slide and latex agglutination with live bacteria, which were subsequently used for differentiation of C. fetus ss. jejuni strains. For this purpose we applied 22 C. fetus ss. jejuni antisera absorbed with boiled homologous bacteria. Clearcut homologous reactions, with few and weak crossreactions, 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 ss. jejuni antisera demonstrated the applicability of this approach for epidemiological studies. We found antigenically similar strains in family outbreaks, antigenic differences in strains of different origin, new combinations of cross reactions not seen in strains used in immunization, antigenically "new" strains not reacting with these antisera, and the dominance of a few antigenic types among the isolates.