Nosocomial diarrhea is any diarrhea that a patient contracts in a health-care institution. In children, it is commonly caused by enteric pathogens, especially rotavirus. The reported incidence ranges from 4.5 to 22.6 episodes per 100 admissions. Nosocomial diarrhea may prolong the hospital stay and increase medical costs. One of the potential strategies for the prevention of nosocomial infections is the use of probiotics. The number of studies have shown the efficacy of Lactobacillus reuteri (DSM 17938) in the treatment of acute diarrhea. However, there are no data on the efficacy of L. reuteri in the prevention of nosocomial diarrhea. The investigators, therefore, plan to perform the study with the aim of evaluating the role of Lactobacillus reuteri DSM 17938 administration in the prevention of nosocomial gastroenteritis in a pediatric hospital setting.

Infants will be randomly assigned at admission to receive L. reuteri in dose of 10(8) CFU in 5 drops of oil suspension or a comparable placebo once daily for the entire duration of their hospital stay.

Patients will be evaluated daily for stool number and consistency. In case of loose or watery stools occurring within 3 days after discharge, patients will be advised to contact hospital physicians. Stool samples obtained weekly and during an episode of diarrhea, will be analyzed for bacteria with standard stool cultures and rotavirus and adenovirus antigen.

Inclusion Criteria:

• age 1-48 mo
• cause of hospitalization must be other than acute gastroenteritis or diarrhea

Exclusion Criteria:

• acute gastroenteritis within 3 days before admission
• other symptoms which suggest gastroenteritis
• usage of probiotics and/or prebiotics within 7 days before admission
• visible blood in the stool
• patient in bad condition
• lack of approval from patients parents
• breastfeeding
• no compliance