An attempt to identify the evolutionary origin of a novel serotype of Salmonella enterica isolated from harbour porpoises

The isolation since 1991 of a new serotype of Salmonella enterica (antigeni c formula 4,12:a:-) from harbour porpoises (Phocoena phocoena) at post-mort em examination raised the question of its evolutionary origin. Representati ve strains of S, enter ica serotype 4,12:a:- and strains of eight other ser otypes of serogroup O4 with phase-1 flagellar antigen II 'a' were examined by EcoRI ribotyping, IS200 fingerprinting and PCR-based profiling, Statisti cal analysis of results of multiple typing showed that strains of Salmonell a serotype 4,12:a:- were genetically distant from those of antigenically si milar salmonella serotypes, none of which seemed likely to be the progenito r of the 'porpoise' serotype.