Evaluation of a 3-dose Vaccination Regimen With One of Three Ascending Dose Levels of Clostridium Difficile Vaccine With or Without Adjuvant in Healthy Adults Aged 50 to 85 Years

Exclusion criteria

• . Previous administration of an investigational C. difficile vaccine or C. difficile monoclonal antibody therapy.
• . Proven or suspected prior episode of CDAD.
• . Unstable chronic medical condition or disease requiring significant change in therapy or hospitalization for worsening disease within 12 weeks before receipt of study vaccine.
• . Serious chronic medical disorders including metastatic malignancy, severe chronic obstructive pulmonary disease (COPD) , end stage renal disease with or without dialysis, clinically unstable cardiac disease, or any other disorder that in the investigator's opinion precludes the subject from participating in the study.
• . Donation of blood volume of 250 mL or greater, or donation of plasma within 3 months prior to enrollment or during the conduct of the study.
• . Bleeding diathesis or condition associated with prolonged bleeding time that may contraindicate intramuscular injection or blood draw including subjects taking anticoagulant, antiplatelet and/or antithrombotic agents except for low dose daily aspirin (≤325mg per day) within 30 days before enrollment through completion of Visit 9 (Month 7).
• . Any contraindication to vaccination or vaccine components.
• . "Immunocompromised persons or subjects currently on immunosuppressive therapy or with a history of immunosuppressive therapy, including chemotherapy agents for treatment of diseases including, but not limited to cancer, inflammatory bowel disease or autoimmune disease. Recent history (within the past 6 months) of long term (7 days or longer) systemic corticosteroid use."