Enterococcus faecalis. Light micrograph (LM) of Enterococcus faecalis bacteria (formerly known as Streptococcus faecalis). These bacteria are rounded or oval-shaped and belong to the streptococci group of bacteria. 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.