Fidaxomicin: a macrocyclic antibiotic for the treatment of Clostridium difficile infection.

Clostridium difficile is an emerging pathogen in certain health care systems and community-based populations that is associated with high rates of morbidity and mortality, as well as increased costs for the health care system. As recurrence rates increase, new pharmacologic agents to treat C. difficile infection are needed. Fidaxomicin, a novel macrocyclic antibiotic, was recently approved by the United States Food and Drug Administration for the treatment of C. difficile-associated diarrhea. Originally isolated from fermentation broth of Dactylosporangium aurantiacum subspecies hamdenensis, the drug has a selective spectrum, distinctive pharmacokinetic and pharmaco-dynamic properties, and a favorable adverse-effect profile. Fidaxomicin has demonstrated similar clinical cure rates (i.e., resolution of diarrhea) compared with vancomycin, with lower recurrence rates and higher global cure rates (i.e., resolution of diarrhea without recurrence) in non-restriction endonuclease analysis type BI, North American Pulsed Field type 1 (NAP1), polymerase chain reaction ribotype 027 (or non-BI/NAP1/027) strains. Overall, fidaxomicin has been generally well tolerated, with the most common adverse effects reported as mild gastrointestinal complaints. Fidaxomicin appears to be a useful agent in the treatment of severe C. difficile infection, demonstrating decreased rates of recurrence.