[Etiology of pediatric inpatients with pneumonia].

The etiology of acute pneumonia was studied in 596 pediatric inpatients at Chiba Municipal Kaihin Hospital between January 1990 and December 1991. A pathogen was identified in 389 (64.4%) episodes of pneumonia. Evidence of bacterial infection was present in 167 (28.8%) episodes, viral infection in 178 (29.9%) and Mycoplasma pneumoniae infection in 89 (14.9%). The major bacterial pathogens were H. influenzae 117 (19.6%), S. pneumoniae 51 (8.6%), M (B). catarrhalis 24 (4.0%). RS virus was the most common respiratory virus. The peak age of the patients was 7 months to 2 years old. For bacterial pneumonia, the highest rates occurred in infants. Mycoplasma pneumonia produced the highest rates in school-age children. Mycoplasma pneumonia was prevalent at two distinct times, the first emerging in the spring of 1990 and emerging again in the autumn of 1991. RS virus and influenza virus epidemics occur during the winter. Most of the parainfluenza virus have been observed during the early summer season.