SEROLOGICAL VARIATION AMONG POLISH ISOLATES OF YERSINIA RUCKERI

One hundred and twenty-six isolates of Yersinia ruckeri originating from different species of fish were collected: 122 from rainbow trout (Oncorhynchus mykiss; Walbaum), three from pike (Esox lucius L.), and one from carp (Cyprinus carpio L.). The Oserotyping of the isolates were carried out for the first time in Poland by microplate agglutination assays according to the Davies procedure. Three O-serotypes were determined: O1, O5, and O7. Serotypes O2 and O6 have not been recognised. Almost all isolates were represented by serotype O1, which originated only from rainbow trout showing classical clinical signs of enteric redmouth disease. The strains representing serotype O5 were only collected from pike and serotype O7 from carp and rainbow trout showing no clinical signs of the diseases.