Enterococcus bacteria. Colonies of Enterococcus faecalis bacteria growing on bile esculin agar in a petri dish. E. faecalis belongs to the streptococci D group of bacteria and was formerly known as Streptococcus faecalis. E. faecalis is a normal inhabitant of the human intestine and is found in faeces. It can also infect the urinary tract and sometimes invades wounds or ulcers on the skin. It may be the cause of bacterial endocarditis (infection of the heart) after surgery. E. faecalis is resistant to a number of antibiotics, including penicillin. Bile esculin agar is used to positively identify D group streptococci.