[Pneumopathies caused by Chlamydia pneumoniae].

Among the atypical pneumonias observed between March 1990 and March 1991, 6 were diagnosed as being caused by Chlamydia pneumoniae of the TWAR strain. The serological diagnosis was obtained by a microimmunofluorescence test. All 6 patients had anti-TWAR antibody levels higher than 512; they were treated with a macrolide administered by the oral route and were cured without sequelae or recurrences. Four cases received a ten day course of roxithromycin 300 mg/day and one case received erythromycin 2 g/day also for 10 days. The sixth case received a short course of azithromycin 500 mg once daily for three days. In 2 other patients presenting with clinical and radiological signs of pneumonia the diagnosis of C. pneumoniae infection could not be made despite an antibody level equal or higher than 512, since the serological results showed cross-reactions between C. pneumoniae, C. trachomatis and C. psittaci antibody responses.