Association of serotype of Streptococcus pneumoniae with risk of severe and fatal outcome.
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.
Rückinger
Simon
S
Institute of Social Pediatrics and Adolescent Medicine, Ludwig-Maximilians-University of Munich, Munich, Germany. simon.rueckinger@med.uni-muenchen.de
von Kries
Rüdiger
R
Siedler
Annette
A
van der Linden
Mark
M
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D011008:Pneumococcal Infections / Q000382:microbiology* / Q000401:mortality*; D012189:Retrospective Studies; D012307:Risk Factors; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification*