Advances in the treatment of Clostridium difficile with fidaxomicin: a narrow spectrum antibiotic.

Clostridium difficile infection, also known as C. difficile-associated diarrhea (CDAD), is the most common cause of nosocomial diarrhea, typically initiated by the use of broad-spectrum antibiotics that disrupt gut flora, thereby allowing C. difficile to proliferate. It is an increasing cause of morbidity and mortality, especially in hospitals and long-term care facilities. A particularly challenging aspect to treating CDAD has been maintenance of clinical response: following initial treatment success, recurrence occurs in approximately 15-30% of patients after the first episode and up to 50-60% subsequently. Fidaxomicin, marketed as DIFICID® in the United States, is approved in multiple countries and is the first new drug to be approved for this indication in over 25 years. It is a novel, narrow spectrum antibiotic with potent bactericidal activity against C. difficile and low activity against the normal gut microbiota. In clinical trials, fidaxomicin has been shown to be noninferior in initial clinical response to CDAD compared to vancomycin, and superior in limiting recurrence and providing sustained clinical response. In this review, the development and characteristics of fidaxomicin are described.