| Abstract: | The antigenic scheme of Wauters and co-workers was applied to serotype a total of 585 strains of Yersinia enterocolitica, 43 strains of Yersinia kristensenii, 40 strains of Yersinia frederiksenii, and 25 strains of Yersinia intermedia. The O antigens 11,23; 11,24; 12,25; 12,26; and 28 were exclusively associated with Y. kristensenii. O antigen 16 was associated with Y. kristensenii and Y. frederiksenii. The serogroups O:4,33 and O:17 were only found in Y. intermedia, whereas the remaining serogroups were associated with Y. enterocolitica. The O antigen 34 proved to be identical with O:10; O factor 29 was poorly expressed and is suggested to be excluded from the list of recognized antigens. As sera of O factors 1, 2a, and 2b of Y. enterocolitica are difficult to prepare, we propose to combine the serogroups O:1,2a,3 and O:2a,2b,3 with O group 3. The H antigens l, r, s, and t were characteristic of Y. kristensenii, whereas H:p was exclusively found in Y. frederiksenii. H:q belonged to Y. intermedia, whereas H:o occurred in Y. kristensenii, Y. frederiksenii, and Y. intermedia. The remaining H factors a to k, m, and n occurred in Y. enterocolitica in various combinations. Up to 15 different combinations of H antigen factors were identified in a single serogroup of Y. enterocolitica. We propose the definition of a new H antigen, u. We suggest the exclusion from the typing scheme of those O and H antigens which are not associated with Y. enterocolitica. For O typing, we present a revised antigenic scheme of Y. enterocolitica with 18 serogroups containing 20 O factors. We emphasize the necessity of its continuous usage, taking into account the international situation. |
