A microagglutination test for Yersinia enterocolitica infection: recognition of multiple serotypes in experiments with stained suspensions of serotype O5,27.

When suspensions of Yersinia enterocolitica were stained with triphenyl-tetrazolium chloride (TTC) their antigenic specificity, as determined by tube and microtitre-plate agglutination tests, was altered. Thus, a TTC-stained suspension of serotype O5,27 detected antibodies to nine O serotypes of Y. enterocolitica in sera from experimentally infected animals but did not cross-react with antisera to organisms of five other unrelated genera including Brucella. The same suspension did, however, cross-react weakly with antisera to four serotypes of Yersinia pseudotuberculosis. The value of this antigen preparation in detecting antibodies to the wide range of Y. enterocolitica serotypes likely to cause infection in man should now be assessed.