Suggest Treatment For E.faecalis?

Hello, my father was diagnosed with E.faecalis. It has been 4 month now for the diagnosis. He has taken a course of antibiotics for a whole month but after conducting another test the bacteria was still in the blood stream. We were told that he needs to enter a hospital right away and start another course of a higher dosage of the antibiotic. However, I don t feel like that is the wise option, since they haven t conducted a drug resistant strains to see if his body is resisting that type of antibiotics. I would like to see if someone here has a different say to treat this bacteria, or if there is another method for treatment. Thank you.