Although oral metronidazole is indicated for mild to moderate Clostridium difficile associated diarrhea, oral vancomycin should be considered first-line therapy in critically-ill patients with moderate to severe disease. Vancomycin dosing should begin at 125mg PO q6 and increased to 250mg q6 if poor enteral absorption exists. Consider adding metronidazole IV if either reduced enteral absorption or severe disease exists.
Recently, fidaxomicin has been shown to be non-inferior to oral vancomycin in the treatment of mild to moderate C. difficile. While promising, the study population was not critically-ill and extrapolation should be avoided.
References
Riddle, D. Clostridium difficile infection in the intensive care unit. Infect Dis Clin North Am. 2009 Sep;23(3):727-43.
