Enterococci (the plural form of the word) are part of the intestinal area of people. According to scientist there are over 17 species in humans and E. faecalis & E. faecium are the most common. More importantly, E faecalium is extremely hardy resistant to treatment (vancomycin-resistant enterococci), and Enterococci are generally resistant to anti-biocitcs and penicillin.
As for diseases of the entercocci, the most common ones are urinary tract infections, bacteremia, bacterial endocarditis, and meningitis. In addition, enterococci are pathogens which can attack elderly people who have been already weakened and other immunocompromised patients, who have been in the hospital for a long time.
In terms of the course of infection, it differs from people to people, but there is usually some abdominal and pelvic infections.