Abstract

The drastic decline of northern sea otters (Enhydra lutris kenyoni) in southwestern Alaska has resulted in them being listed as threatened. Valvular endocarditis due to Streptococcus infantarius subspecies coli is a major problem in the northern sea otter population where 50% of 130 carcasses collected over the past three years have had valvular endocarditis. Valvular endocarditis and septicemia have also occurred in southern sea otters (Enhydra lutris nereis) in two cases. Isolates of S. infantarius ss coli and related species from 33 northern sea otters and two southern sea otters that died due to valvular endocarditis or septicemia and 9 healthy live-captured Steller sea lions were genotyped using pulsed-field gel electrophoresis. We are awaiting confirmation from the Centers for Disease Control of the species of some of the more recent Streptococcus isolates from sea otters, therefore the terminology S. infantarius ss coli and related species is being used. Approximately 90% of the isolates from northern sea otters produced similar banding patterns indicating the isolates are highly related. The high degree of similarity among the isolates suggests they may be unique. Approximately 10% of the northern sea otter isolates produced distinct banding patterns suggesting they are unrelated strains. Two southern sea otters died of valvular endocarditis and septicemia in 2004. The isolates from the two animals produce identical banding patterns, but they are distinct from the northern sea otter isolates. S. infantarius ss coli and related species were often isolated from multiple organs in the sea otter. Isolates obtained from the same animal produced identical banding patterns, indicating the infecting strain spread throughout the animal's body. S. infantarius ss coli have not been isolated from healthy sea otters, so isolates from Alaskan Steller sea lions were included in the study to determine if S. infantarius ss coli isolated from healthy animals are related genotypically to isolates from sea otters with valvular endocarditis. Two genotypes were identified in the isolates from Steller sea lions; both were distinct from all of the sea otter isolates. These results indicate that the S. infantarius ss coli isolates infecting Steller sea lions are unrelated to the isolates causing valvular endocarditis in sea otters.

Acknowledgements

This project was supported by the California Department of Fish and Game's Oil Spill Response Trust Fund through the Oiled Wildlife Care Network at the Wildlife Health Center, School of Veterinary Medicine, University of California, Davis.