Chlamydia pneumonia in infants: radiography in 125 cases.

Chlamydia trachomatis was recently discovered to be the causative organism in a distinctive afebrile pneumonia occurring in infants under 6 months of age. Experience with the first 125 cases seen at this hospital during a 3 1/2 year period is reported. Chest radiographs were reviewed of 2,273 infants in this age group with signs of lower respiratory tract infection. The first group comprised 148 patients admitted to the hospital. Chlamydia pneumonia was diagnosed in 41 cases. The second group of 2,125 infants was first seen in the outpatient department where 84 additional cases were detected. From this experience it was concluded that, although there are no radiographic findings specific for Chlamydia pneumonia, a combination of the clinical and radiographic findings strongly suggests the diagnosis before cultures and serum antibody titers are available. Important clinical features include age of onset at 2-14 weeks of age, cough, lack of fever, and elevated serum immunoglobulins. Most chest films show bilateral hyperexpansion and diffuse infiltrates with a variety of radiographic patterns including interstitial, reticular nodular, atelectasis, coalescence, and bronchopneumonia. Pleural effusion and lobar consolidation are not seen. The radiographic changes often suggest a more serious illness than that observed clinically. Radiographic features are described in detail.