Hypothesis: Use of Bifidobacterium animalis subsp. lactis can effectively prevent common nosocomial (gastrointestinal and respiratory) infections. Nosocomial infection will be defined as infections which develop more than 48 hours after admission and they are not present or incubating on admission

This study is a prospective, randomized, double blind, placebo- controlled parallel study in children hospitalized at Children's hospital Zagreb.

The study will investigate the effect of supplementation with the probiotic strain Bifidobacterium animalis subsp. lactis on the incidence and duration of gastrointestinal and respiratory infections.

The test product is a sachet containing 1 gram of powder. The test product will contain minimum 1 billion CFU (colony forming units) probiotic per serving.

The placebo product is an identical product except for the absence of probiotics.

The study includes an intervention period lasting the length of the hospital stay.

The study product will be consumed daily in the morning together with breakfast.

The consumption of the study products will be taken under the surveillance of the physician.

Data on infections will be diagnosed by a physician and recorded in a CRF. The incidence of infections will be analyzed based on the information recorded in the CRF.

Inclusion Criteria:

• Children hospitalized at the Department of Paediatrics, Children's Hospital Zagreb
• Age from 1 year to 18 years
• Signed informed consent by the parents

Exclusion Criteria:

• Immunodeficiency
• Infants from neonatal period until 1 year of age
• Re-hospitalisation (readmission in a hospital within one month)
• Receiving probiotic and /or prebiotic products prior to enrolment (2 weeks prior to hospitalization)
• Neoplasms
• Severe chronic diseases
• Hospitalization shorter than 3 days