Study was terminated early due to slow recruitment.

The primary objective of the study is to demonstrate non-inferiority of nitazoxanide compared to vancomycin in resolving symptoms of Clostridium difficile-associated disease (CDAD).

Inclusion Criteria:

• Age ≥ 18 years.

• Patients with new onset of disease evidenced by diarrhea (≥ 3 unformed stools within 24 hours), and one or more of the following symptoms of CDAD:

  • abdominal pain or cramps
  • peripheral leukocytosis
  • fever

• C. difficile toxin A or B detected in a stool specimen obtained within 3 days before enrollment by enzyme immunoassay.

• Patients willing to avoid the following medications during the study:

  • oral and intravenous metronidazole
  • oral vancomycin
  • anti-peristaltic drugs
  • opiates (patients on opiates may be included in the study if they were taking opiates prior to enrollment and the dose is not increased during the study)
  • Saccharomyces cerevisiae (baker's yeast)
  • Lactobacillus GG
  • cholestyramine
  • colestipol

Exclusion Criteria:

• Patients with other known causes of diarrhea or colitis (e.g., Shigella, Salmonella, Cryptosporidium parvum, Giardia lamblia, Entamoeba histolytica, inflammatory bowel disease, irritable bowel syndrome, advanced AIDS or chemotherapy for malignancy).
• Patients that commonly have 3 or more stools per day and/or severe abdominal pain in the absence of CDAD.
• Patients with severe lactose intolerance.
• Patients with more than 1 recurrence of CDAD during the 6 months prior to enrollment.
• Patients unable to take oral medications.
• Use within 1 week of enrollment of any drug or therapy with anti-C. difficile activity such as oral or intravenous metronidazole and oral vancomycin. [Patients that have taken up to 3 doses of metronidazole or vancomycin can be included in the study].
• Females of child bearing age who are either pregnant, breast-feeding or not using birth control and are sexually active.
• Patients who are either clinically unstable (e.g., fulminant disease patients with signs of toxic megacolon, imminent perforation, colectomy or death) or unlikely to live throughout the 31-day duration of the study due to underlying illness.
• History of hypersensitivity to nitazoxanide or vancomycin or any active ingredient in the formulations.