The Streptococcus bovis/Streptococcus equinus complex includes four major species that all belong to group D streptococci (GDS); this taxonomy was established in 2003 and is summarized in the Table (table 1) . For simplicity, the Streptococcus bovis/Streptococcus equinus complex will be referred to as GDS in discussion below.
GDS are gram-positive cocci that are an important cause of bacteremia and infective endocarditis (IE) in adults. Because there is a strong association between infections with GDS and colonic neoplasms and other lesions of the gastrointestinal tract, evaluation of the gastrointestinal tract with colonoscopy is important for patients with infections due to this organism .
GDS species and subspecies differ in their microbiology, pathogenesis, and epidemiology. Most clinical microbiology laboratories in the United States use automated testing equipment or other methods to identify these organisms to the species and subspecies level. However, some laboratories continue to report them under the common name S. bovis or S. bovis group .
Associations with endocarditis and colonic neoplasm are most closely linked to S. gallolyticus subspecies gallolyticus (S. bovis biotype I) [2,4-6]. S. bovis biotype II bacteremias may be more associated with biliary tract disease and more likely to be polymicrobial [4,7]. S. gallolyticus subspecies pasteurianus has been identified as a cause of infections in neonates and infants [1,8]. However, the published literature regarding these organisms does not always distinguish S. bovis isolates to the biotype and/or subspecies level consistently .
The clinical manifestations, diagnosis, and therapy of Streptococcus bovis infection will be reviewed here. The microbiology, pathogenesis, and epidemiology of GDS infection are discussed separately. (See "Microbiology, pathogenesis, and epidemiology of infections due to group D streptococci (Streptococcus bovis/Streptococcus equinus complex)".)