Abstract
Antigenic relationships among type-3 fimbriae of 31 strains, representing 19 speies and 8 genera of Enterobacteriaceae, were investigated by immunoEM in test with 17 different type-3 fimbrial antisera. At least 9 antigenically distinct groups among type-3 fimbriae were distinguished. The constituent membership of some groupings did not conform with current views on the taxonomy of Enterobacteraceae.