The purpose of this study is to evaluate the efficacy and safety of Bio-K+ CL-1285 in the prevention of Antibiotic-Associated Diarrhea (AAD) and Clostridum difficile-Associated Diarrhea (CDAD) in hospitalized patients exposed to nosocomial infection.

Inclusion Criteria:

• Antibiotic therapy for a minimum of 3 days and a maximum of 14 days
• Expected to remain hospitalized for a minimum of 5 days
• Patients who have received less than 36 hours of antibiotic therapy
• Negative pregnancy test at screening
• Obtained his/her informed consent after verbal and written information
• Patients having a telephone available (mobile, work, home)
• Patients having a fridge at home

Exclusion Criteria:

• Pregnant or breastfeeding women
• Patients presenting with active diarrhea (3 or more liquid stools per 24 hour period).
• Patients with a history of daily consumption of probiotics, fermented milk and/or yogurt;
• Patients known to have shown a previous reaction, including anaphylaxis, to any substance in composition of the study product (i.e. Non-medicinal ingredients: Cellulose, hypromellose, magnesium stearate (vegetal source), ascorbic acid, Colloidal silicon dioxide)
• Patients presenting with an active, non-controlled intestinal disease such as Crohn's Disease or ulcerative colitis;
• A previous documented C. Difficile infection < 3 months prior to study initiation ;
• Ostomized patients, parenteral nutrition users
• Patients with an immunosuppressive therapy or any health condition causing immunosuppression (including haematological malignancies, acquired immune deficiency syndrome (AIDS))
• Ongoing or recent use of antibiotic therapy in the 30 days prior to the study product first administration.
• Patients with planned administration of antibiotics other than broad spectrum Penicillin, Cephalosporin or Clindamycin for the treatment of an infection;
• Patients with concomitant participation in another clinical trial;
• Patients who are not likely to comply with study requirements