Objective: The objective of this study was to determine the rate, risk factors, and outcomes of nosocomial primary bloodstream infection in pediatric intensive care unit (PICU) patients.

Design: Prospective cohort study.

Settings: This study was performed at St Louis Children's Hospital, a 235-bed academic tertiary care center with a combined 22-bed medical and surgical PICU.

Patients: Subjects for this study were patients admitted to the PICU between September 1, 1999, and May 31, 2000.

Interventions: None.

Outcome measures: Patients were monitored for the development of nosocomial bloodstream infections from the day of PICU admission until 48 hours after PICU discharge.

Results: Of 911 patients, 526 (58%) were male and 674 (74%) were white. Congenital heart disease (29%), lung disease (25%), and genetic syndrome (18%) were common. There were 65 episodes of primary bloodstream infection in 57 patients; 5 were polymicrobial and 7 patients had multiple bloodstream infections. Coagulase-negative Staphylococcus was the leading cause of bloodstream infection (n = 28), followed by Enterobacter cloacae (n = 8). The rate of bloodstream infection was 13.8 per 1000 central venous catheter days. In multiple logistic regression analysis, patients with bloodstream infection were more likely to have multiple central venous catheters (adjusted odds ratio [aOR]: 5.7; 95% confidence interval [CI]: 2.9-10.9), arterial catheters (aOR: 5.5; 95% CI: 1.8-16.3), invasive procedures performed in the PICU (aOR: 4.0; 95%CI: 2.0-7.8), and be transported out of the PICU (aOR: 3.4; 95% CI: 1.8-6.7) to the radiology or operating room suites. Severity of illness as measured by admission Pediatric Risk of Mortality score, underlying illnesses, and medications were not associated with increased risk of nosocomial bloodstream infection. Conclusions This study identified a high rate of bloodstream infection among St Louis Children's Hospital PICU patients. Risk factors for bloodstream infection were related more to process of care than to severity of illness. Additional research is needed to develop interventions to reduce nosocomial bloodstream infections in children.