IDENTIFICATION AND TYPING OF VIBRIO-ANGUILLARUM - A COMPARISON OF DIFFERENT METHODS

The majority (91%) of 260 isolates initially identified as Vibrio angu illarum, that were obtained from a wide range of hosts, habitats and g eographical locations, were recovered in a single cluster based on the ribotype and were pathogenic to Atlantic salmon. A significant propor tion of isolates (78% of the total) were allocated to 15 serogroups (O 1 - O10 and five previously undescribed groups referred to as VaNT1, V aNT2, VaNT4, NaNT5 and VaNT7). A minority of isolates (6%) reacted wit h more than one antiserum or were self-agglutinating, and the remainde r did not react with any of the antisera tested. Good correlation was noted between serogroups and lipopolysaccharide profiles, particularly with respect to isolates belonging to serogroups O1, O2 and O4 - O10. Plasmids were recognized in some serogroups, especially O1, which con tained the 67 kb plasmid associated with virulence. However, the 19 pr ofiles based on outer membrane protein patterns did not correspond to the results obtained with the other typing methods. Generally, the iso lates were heterogeneous in their biochemical characteristics; 117 pro files were obtained with the API20E system, and 9 and 32 clusters reco gnised from the results of BIOLOG fingerprinting and Biotype-100 bioty ping methods, respectively. Three dominant clusters were defined from fatty acid methyl esters profiles.