CLASSIFICATION OF PASTEURELLA FIELD STRAINS ISOLATED FROM FARMS IN GERMANY USING TRADITIONAL METHODS AND DNA-DNA HYBRIDIZATION

410 Pasteurella (P.) field strains isolated from calves and piglets we re classified according to Bisgaard et al. (1). 376 strains were assig ned to P. multocida ssp. multocida, 34 of them were ornithine- and tre halose+, and 61 of them ornithine- and trehalose-. 4 strains belonged to P. multocida ssp. septica, 4 to P. multocida ssp. gallicida, 6 to P . avium biovar 2 and 20 to P. canis biovar 2. There was no difference in the prevalence of the species in calves and pigs. The fact that str ains belonging to P. multocida ssp. septica were isolated only from ca lves and P. multocida ssp. multocida ornithine- and trehalose- were mo stly isolated from piglets could indicate a certain host specificity o f these isolates. In genotypic investigations 20 field isolates of P. multocida belonging to different Carter serotypes, as well as serologi cally negative strains were compared to reference strains in terms of deoxyribonucleic acid (DNA) relatedness. The data obtained by filter h ybridization revealed a considerable degree of genotypic intraspecies heterogeneity within P. multocida. No correlations to the respective s erotypic classification could be detected.