Background: Invasive pneumococcal disease (IPD) in children may manifest as bacteremia/sepsis, bacteremic pneumonia, or meningitis, with serious outcomes that include hospitalization, neurologic sequelae, or death. The risk of severe or fatal outcome of disease is associated with host-related factors, such as age or comorbid conditions. Furthermore, there is an ongoing discussion about organism-related factors, such as the pneumococcal serotype.
Methods: Data on 494 children aged <16 years hospitalized for IPD between 1997 and 2003 in pediatric hospitals in Germany were analyzed. Serotype specific case-fatality rates and rates of severe outcome were compared using standardized mortality ratios (SMR). The risk of severe or fatal outcome for the serotype with the highest case-fatality rate was further analyzed using multivariate logistic regression adjusting for age younger than 1 year, meningitis, sex, and immunocompromised status as potential confounders.
Results: The overall case-fatality rate was 5.3% and the rate of severe outcome was 17.0%. Serotype 7F had the highest case-fatality rate (14.8%, SMR 3.1), followed by serotypes 23F (8.3%, SMR 1.7) and 3 (8.3%, SMR 1.7). The highest rate of severe outcome was also observed for 7F (40.7%, SMR 2.4). Multivariate analysis showed an odds ratio of 4.3 (1.3–14.7) for fatal outcome and 4.0 (1.6–10.4) for severe outcome comparing 7F to all other serotypes.
Conclusions: In this study population, serotype 7F accounted for a higher risk of severe and fatal outcome than other serotypes of Streptococcus pneumoniae. In describing the epidemiology of IPD, the serotype-specific risk for severe or fatal outcome is an important complement to other serotype-specific aspects like incidence and antibiotic resistance pattern.
From the *Division of Epidemiology, Institute of Social Pediatrics and Adolescent Medicine, Ludwig-Maximilians-University of Munich, Munich, Germany; †Robert Koch Institute, Berlin, Germany; and ‡Institute of Medical Microbiology and National Reference Centre for Streptococci, University Hospital RWTH Aachen, Aachen, Germany.
Accepted for publication July 24, 2008.
Supported in part by grant RKI-415/1369235 from the German Ministry of Health (to B.F.G.), and by a grant from Wyeth, Germany.
Address for correspondence: Simon Rückinger, MSc, Division of Epidemiology, Ludwig-Maximilians-University of Munich, Institute of Social Pediatrics and Adolescent Medicine, Heiglhofstr 63, 81377 München, Germany. E-mail: firstname.lastname@example.org.