Identification and molecular characterization of beta-hemolytic streptococci isolated from harbor porpoises (Phocoena phocoena) of the North and Baltic Seas.

The present study was designed to identify and comparatively investigate 35 beta-hemolytic streptococci isolated from stranded harbor porpoises or from animals caught in fishing nets of the North and Baltic seas. According to biochemical and serological data and to lectin agglutination tests with the lectin of Arachis hypogaea, all 35 isolates could be classified in Lancefield's serological group L and could be identified as Streptococcus dysgalactiae subsp. dysgalactiae. All 35 group L streptococci were uniformly sensitive to most of the antibiotics tested. To further analyze the epidemiological relationship, the isolates were subjected to macrorestriction analysis of their chromosomal DNA by pulsed-field gel electrophoresis. Digestion of the chromosomal DNA with the restriction enzymes SmaI and ApaI revealed that most of the group L streptococci seemed to be apparently identical or related. These results indicate that one clone or at least related group L streptococcal clones play an important role for infections of harbor porpoises of the North and Baltic seas. This might possibly be caused by a direct transfer of the bacteria from animal to animal.