Efficacy and Safety of Cadazolid Versus Vancomycin in Subjects With Clostridium Difficile - Associated Diarrhea

Inclusion Criteria: * Signed Informed Consent. * Male or female ≥ 18 years of age. Females of childbearing potential must agree to use an adequate and reliable method of contraception. * Subject with a diagnosis of mild-moderate or severe CDAD (first occurrence or first recurrence within 3 months) with: Diarrhea: a change in bowel habits with \> 3 liquid or unformed bowel movements (UBM) within 24 hours prior to randomization, AND Positive C. difficile toxin test on a stool sample produced within 72 hours prior to randomization. Exclusion Criteria: * More than one previous episode of CDAD in the 3-month period prior to randomization. * Evidence of life-threatening or fulminant CDAD. * Likelihood of death within 72 hours from any cause. * History of inflammatory colitides, chronic abdominal pain, or chronic diarrhea. * Antimicrobial treatment active against CDAD administered for \> 24 hours except for metronidazole treatment failures (MTF) * Known hypersensitivity or contraindication to study drugs, oxazolidinones, or quinolones. * Unable or unwilling to comply with all protocol requirements. * Any circumstances or conditions, which, in the opinion of the investigator, may affect full participation in the study or compliance with the protocol