Evidence of systemic dissemination of Chlamydia pneumoniae via macrophages in the mouse

Although Chlamydia pneumoniae is a respiratory pathogen, there is increasing evidence of involvement of the organisms in anatomic sites other than the respiratory tract. A mouse model was used to study dissemination of organisms following intranasal, intravenous, and subcutane-ous inoculation with C. pneumoniae. After inoculation by any of the three routes, the organism was isolated consistently from lungs and spleen. It was also detected in peritoneal macrophages after intranasal and intravenous inoculation. The ease with which the organism was disseminated in the mouse model raises the question of whether similar spread from the respiratory tract occurs in human C. pneumoniae infection. Chlamydia pneumoniae, also called TWAR, is a common human respiratory pathogen [I). To study the pathogenesis of C. pneumoniae lung infection, we developed a mouse model of C. pneumoniae pneumonitis [2). Our studies showed that intranasal inoculation of Swiss-Webster mice with C. pneumoniae induced a prolonged course of lung in-fection; organisms were reisolated from lungs for 42 days an