ETIOLOGY OF CHILDHOOD PNEUMONIA - SEROLOGIC RESULTS OF A PROSPECTIVE,POPULATION-BASED STUDY

Background To investigate the etiology of pediatric community-acquired pneumonia, we conducted a prospective, population-based study coverin g the total population <15 years of age (n = 8851) in 4 municipalities in eastern Finland. Materials and methods. The number of patients was 201; chest radiographs were available for all cases and paired sera f or serologic assays were available for >90% of cases. The methods incl uded assays for antibody response to 3 pneumococcal antigens, specific pneumococcal immune complex assays and conventional antibody tests fo r mycoplasmal, chlamydial and viral infections. Results. Serologic evi dence of specific microbial etiology was obtained in 133 (66%) of the pneumonia patients. Bacterial infection was diagnosed in 102 cases (51 %) and viral infection in 51 cases (25%). Streptococcus pneumoniae was the most common agent (57 cases; 28%), followed by Mycoplasma pneumon iae (44; 22%), respiratory syncytial virus (43; 21%) and Chlamydia spp . (29; 14%). Haemophilus influenzae was identified in only 6% and Mora xella catarrhalis in only 3% of the children. More than one specific i nfection was found in 51 patients (25%). The proportion of pneumococca l cases varied from 24 to 36% by age. Mycoplasma infections were seen mostly in patients greater than or equal to 5 years and Chlamydia infe ctions in patients greater than or equal to 10 years of age. Conclusio ns. The results of our prospective, strictly population-based study co nfirm the importance of S. pneumoniae in the etiology of community-acq uired pneumonia in children of all ages. M. pneumoniae and Chlamydia p neumoniae are important from the age of 5 years onwards.