The enterococcus group is a subgroup of the fecal streptococci. The enterococci portion of the streptococcus group is a valuable bacterial indicator for determining the extent of fecal contamination of recreational surface waters. Studies in marine and fresh water studies indicate that enterococci are the most efficient bacterial indicator of water quality. Enterococcus is a bacteria found in the human intestine and therefore a good indicator of human waste.
Another site says "Pathology Enterococci are the leading cause of nosocomial infection (or secondary infection aquired while in a hospital). They are responsible for approximately 110,000 cases of urinary tract infection, 25,000 cases of bacteremia, 40,000 wound infections, and 1,100 cases of endocarditis yearly in the United States. To infect hosts enterococci primarily colonize mucosal surfaces. They also must evade host defenses although little is known about the actual mechanism of evasion. The pathogenicity of the organism is believed to be closely associated with its ability to produce cytolysin, a toxin that causes rupture of a variety of target membranes, including bacterial cells, erythrocytes, and other mammalian cells."