Phenotypic and genotypic diversity of organisms previously classified as maltose positive Pasteurella multocida

Fifteen isolates tentatively classified as maltose positive Pasteurella multocida have been characterized in 79 biochemical tests and by ribotyping using HindIII and HpaII for digestion of DNA. Phenotypic and genotypic results were analysed using the computer programmes NTSYS and GelCompar, respectively. Two strains were classified as maltose positive P. multocida ssp. multocida while six strains were classified as maltose positive P. multocida ssp. septica. The remaining strains clustered with P. volantium and P. gallinarum, but remained unclassified. With the exception of a single isolate correlation was observed between phenotypic and genotypic results. The unclassified isolates which represented three different sources were heterogenous according to both phenotypic and genotypic results. The findings obtained support the 16S rRNA sequencing results indicating that the genus Pasteurella sensu stricto might represent two or more genera.