Radiographic appearance of Chlamydia pneumoniae (TWAR strain) respiratory infections

PURPOSE: To report the spectrum of radiographic findings associated with a new respiratory pathogen: Chlamydia pneumoniae (TWAR strain). MATERIALS AND METHODS: Radiographs of 55 adult patients hospitalized with serologic evidence of C pneumoniae were retrospectively reviewed. RESULTS: On the basis of serologic criteria, two types of acute respiratory infection are possible: primary (first exposure) infections and recurrent, acute infection in a previously exposed individual. In the primary group, alveolar opacities (65%) with a unilateral distribution (71%) were most common at admission. Cavitary disease and hilar or mediastinal lymphadenopathy were uncommon. Small to medium-sized pleural effusions were common in both primary and recurrent groups during hospitalization. Also, both groups tended to progress to bilateral, mixed, interstitial and alveolar changes during the course of infection. CONCLUSION: Different radiographic patterns exist for the two types of acute C pneumoniae infection.