Valvular endocarditis and septicemia due to Streptococcus infantarius subspecies coli is a major cause of mortality in the northern sea otter (Enhydra lutris kenyoni) population. Valvular endocarditis and septicemia have also occurred in southern sea otters (Enhydra lutris nereis) in five cases. It is thought that S. infantarius ss coli initially colonizes the host's gastrointestinal tract (GIT) and under certain circumstances can escape the GIT and cause endocarditis.1,2 The ability of 21 S. infantarius ss coli isolates to adhere to and invade epithelial and endothelial cells was investigated to examine an aspect of the bacteria's pathogenicity. Three of the isolates tested adhered significantly to a human epithelial cell line, and two of the isolates also invaded significantly. The ability of certain strains to adhere to epithelial cells would allow them to colonize the GIT, and their ability to invade suggests they could translocate across the GIT and access other parts of the body. Although most of the S. infantarius ss coli strains adhered to epithelial and endothelial cells at low levels, some strains invaded the cells at levels equivalent to adherence. The ability to invade host cells may be an indication of their ability to evade host defenses, persist in the host, and cause tissue damage.
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, CA.
1. Muhlemann K., S. Graf, and M. Tauber. 1999. Streptococcus bovis clone causing two episodes of endocarditis 8 years apart. J Clinical Microbiol 37: 862-863.
2. Waisberg J., C. Matheus, and J. Pimenta. 2002. Infectious endocarditis from Streptococcus bovis associated with colonic carcinoma: case report and literature review. Arq Gastroenterol 39: 177-179.