Enterococci

ENTEROCOCCI

BACTERIOLOGY

Until DNA homology studies dictated their separation into the genus Enterococcus, the en-terococci were classified as streptococci. Indeed, the most common enterococcal species share the bacteriologic characteristics described above for pyogenic streptococci, including presence of the Lancefield group D antigen. The term enterococcus derives from their presence in the intestinal tract and the many biochemical and cultural features that reflect that habitat. These include the ability to grow in the presence of high concentrations of bile salts and sodium chloride. Most enterococci produce nonhemolytic or β-hemolytic colonies that are larger than those of most streptococci. E. faecalis, E. faecium, and several other species are recognized based on biochemical and cultural reactions, but enterococci are generally not speciated in the clinical laboratory.