Although limited prospective randomized clinical trials showed no statistical differences among treatment agents for cessation of diarrhea (the primary outcome endpoint; Table 123-2), later observational studies suggest that response rates to metronidazole may have decreased. The clinical response rate for bacitracin is 10–20% lower than that for vancomycin; therefore, bacitracin use for first-line therapy is discouraged. All drugs, particularly vancomycin, should be given orally if possible. When IV metronidazole is administered, fecal bactericidal drug concentrations are achieved during acute diarrhea, and CDAD treatment has been successful; however, in the presence of adynamic ileus, IV metronidazole treatment of PMC has.
