Prospective surveillance for atypical pathogens in children with community-acquired pneumonia in Japan.

A total of 141 children with community-acquired pneumonia (CAP) were studied prospectively to determine the causative microorganisms. Microbial investigations included examination of postnasal swabs, cultures, polymerase chain reaction (PCR), and serology. The atypical pathogens occurring most frequently were Mycoplasma pneumoniae (58 patients [41.1%]), Chlamydia pneumoniae (4 patients [2.8%]), and concurrent occurrence of both pathogens (1 patient [0.7%]). Patients aged under 4 years showed a relatively lower rate of atypical bacterial etiology compared with those aged 4 years or older. Major bacterial pathogens were detected in 89 patients (atypical pathogens were detected in 28 patients simultaneously), including Streptococcus pneumoniae in 34 patients, Haemophilus influenzae in 60, Moraxella catarrhalis in 48, and multiple pathogens in 42. In patients suspected of having atypical pneumonia, macrolides are recommended.