Objective: The prime objective was to evaluate the incidence of infections and infectious complications in children admitted to the Paediatric Intensive Care Unit (PICU) during years 2004–2005. The second goal was to differentiate between primary endogenous (PE), secondary endogenous (SE) and exogenous (EX) infections and to compare this classification with the CDC criteria for nosocomial infections. The last goal was to find out the most frequent pathogens responsible for nosocomial infections in PICU. Design: Prospective observational study. Setting: Paediatric Intensive Care Unit, Department of Anaesthesiology and Intensive Care in aTertiary University Children’s Hospital. Materials and methods: All children admited to PICU for more than 72 hours in 2004–2005 were enrolled in the study. Children who had had an infection before their admission and those who did not develop an infection within this admission were excluded from the study. Surveillance samples (throat, nose, and stool) were collected on admission and then twice a week (Monday, Thursday). Diagnostic samples were collected if an infection was suspected according to the clinical condition and laboratory findings (tracheal aspiration, bronchoalveolar lavage, blood, urine, smear etc.). Infections were classed as PE, SE or EX and their incidence was compared with the CDC criteria for nosoco - mial infections. For a statistic evaluation, the Fisher exact test, Pearson chi-kvadrat test and Mann-Whitney U test were used. P < 0.05 was considered as statistically significant. Results: A total of 617 patients were admitted in years 2004–2005. Two hundred and sixty four of them were hospitalized for more than 72 hours and 86 of them had an infection on admission. Thus 178 patients were enrolled into the study. Forty-four patients developed an infection (24.7%). Twenty-five patients (61.3%) had PE, 10 patients (22.7%) had SE and 7 patients (15.9%) had an EX infection. SE and EX infections are considered as nosocomial, thus 17 patients (38.6%) had a nosocomial infection. Thirty-one patients (70.5%) met the CDC criteria for nosocomial infections. Seventeen patients (55%) were classified as PE and 14 patients (45%) had SE or EX infections. The most frequent infection in all categories (PE, SE and EX) was lower respiratory tract infection (95%). The most frequent pathogens were Candida albicans, Escherichia coli and Staphylococcus aureus. Conclusion: Seventy percent of infections (31 out of 44 patients) met the CDC criteria for nosocomial infections. Only 39% of infections (17 out of 44 patients) were classified as nosocomial based on the carrier state classification. Incidence of nosocomial infections is considered one of the factors influencing the quality of care of critically ill patients. Thus a precise classification of nosocomial infections is crucial.

        Key words: intensive care – children – infection – nosocomial – endogenous – exogenous