Prevalence of Chlamydia pneumoniae in acute lower respiratory infection in the pediatric population in Japan.

Chlamydia pneumoniae has been established as an important etiologic agent of acute respiratory tract infection in humans, especially in adults. However, there is little information available on C. pneumoniae infection in the pediatric age group. The microimmunofluorescence test and Chlamydia pneumoniae-specific polymerase chain reaction (PCR) method were applied to reveal the role of C. pneumoniae as an etiologic agent of acute lower respiratory tract infection in children in Japan. Among 136 patients aged between 2 months and 15 years with acute lower respiratory tract infection, five patients with pneumonia were found to have recent C. pneumoniae infection by the microimmunofluorescence test. C. pneumoniae-specific PCR products were detected from specimens of four patients among these five. Neither C. trachomatis nor C. psittaci infection was found in this population. These results suggest that C. pneumoniae is an important causative agent of acute childhood pneumonia and may be the most prevalent pathogen among the genus Chlamydia that causes acute lower respiratory disease in this age group in Japan.