Changing epidemiology of pediatric Staphylococcus aureus Bacteremia in Denmark from 1971 through 2000

Background: Staphylococcus aureus is known to be a leading cause of bacteremia in childhood, and is associated with severe morbidity and increased mortality. To determine developments in incidence and mortality rates, as well as risk factors associated with outcome, we analyzed data from 1971 through 2000. Methods: Nationwide registration of S. aureus bacteremia (SAB) among children and adolescents from birth to 20 years of age was performed. Data on age, sex, source of bacteremia, comorbidity and outcome were extracted from discharge records. Rates were population adjusted and risk factors for death were assessed by multivariate logistic regression analysis. Results: During the 30-year study period, 2648 cases of SAB were reported. Incidence increased from 4.6 to 8.4 cases per 100,000 population and case-mortality rates decreased from 19.6% to 2.5% (P = 0.000 1). Incidence in the infant age group (< 1 year) were 10-to 17-fold greater compared with that in the other age strata and mortality rate was twice as high. Hospital-acquired infections dominated the infant group, accounting for 73.9%-91.0% versus 39.2%50.5% in the other age groups. By multivariate analysis, pulmonary infection and endocarditis for all age groups, comorbidity for the older than I year, and hospital-acquired infections for the oldest group were independently associated with an increased risk of death. Conclusions: Mortality rates associated with SAB decreased significantly in the past 3 decades, possibly because of new and improved treatment modalities. However, incidence rates have increased significantly in the same period, underscoring that S. aureus remains an important invasive pathogen.