Dear Sandy,
It sounds like the doctors are not sure that your husband has endocarditis (infection of the heart valve) but they are treating him as if he does to be on the safe side. As long as he is getting good antibiotic coverage at home a temperature of 100.9 is not necessarily enough to keep him in the hospital. There may be other factors however and his doctors will have to decide if he is ready for discharge or not. The other patient in the room although annoying is not dangerous from an infectious standpoint to your husband. If he remains in the hospital you could request a transfer to a private room or another semi-private room.
Here is a good web site with more information about endocarditis:
http://www.amhrt.org/catalog/Heart_catpage17.html
I would be concerned about the roommate after your husband had a PICC line inserted. If his roommate is touching feces and urine then touches things your husband comes into contact with (doorknobs, etc.), he could become septic from cross-contamination. It is extremely important nurses wash their hands before touching the PICC line, even more so if the same nurse takes care of your husband and his roommate. Many nurses just put gloves on over dirty hands, and that's not good enough. What an unpleasant situation to say the least! Best wishes to you and your husband, may he have a speedy recovery.