TAIPEI, Taiwan – Taipei-based OBI Pharma Inc. has entered a deal with Merck & Co. Inc., of Kenilworth, N.J., for the development and commercialization in Taiwan of its narrow-spectrum macrocyclic antibiotic Dificid (fidaxomicin), which is used to treat Clostridium difficile-associated diarrhea (CDAD). The collaboration represents a long-awaited milestone for OBI as its first major revenue-stream generating deal since its formation in 2002.