Description Optimer Pharmaceuticals has good reason to be optimistic: its lead drug Fidaxomicin kills a wicked and persistent bacteria better than anything else. Presented under the market name Dificid, Fidaxomicin has been approved for treating Clostridium difficile-associated diarrhea, commonly acquired in hospitals. Its Pruvel antibiotic is also in late-stage clinical trials for the treatment of infectious traveler's diarrhea. Through the manipulation of carbohydrates, the company is using its OPopS technology to identify other potential drug candidates for diseases such as breast cancer and respiratory tract infections.