Metronidazole
"This medicine has saved me from surgery twice now.  The first time was when I was first diagnosed with Crohn's Ileitis and had an abscess in my abdomen from a crack in my intestines and also several fistulas.  One doctor wanted to remove them surgically, another said lets try metronidazole.  So I was given IV metro for a couple days and then 1000 mg/day for a week or two (can't recall exactly how long it was), and the infection completely disappeared.  I was also given Humira, but that certainly didn't help with the infection.  The second time is actually right now.  My GI doc said I need surgery to remove my appendix and resect my ileum.  My bloodwork was showing infection, but I was put on 1000 mg/day of metronidazole and now its gone."