Chlamydia pneumoniae respiratory infections among patients infected with the human immunodeficiency virus.

Thirteen cases of Chlamydia pneumoniae infection in patients seropositive for the human immunodeficiency virus (HIV) are described. The occurrence, the clinical spectrum, and the significance of the infection during HIV disease are compared with data reported in the literature. Chlamydia pneumoniae infection was established by a serologic micro-immunofluorescence test using standard diagnostic criteria. In four cases the results of serological tests were confirmed by direct immunofluorescence on respiratory specimens. Five patients developed focal pneumonia but recovered completely after specific antibiotic treatment. Three patients developed severe and diffuse interstitial pulmonary involvement, two of whom died of acute respiratory failure. Five patients developed upper respiratory tract infection. Using 39 pair-matched HIV-seropositive subjects as controls, the cases of infection were found to be significantly associated with a previously diagnosed pulmonary disease. Upon retrospective analysis of 319 consecutive cases of pneumonia among HIV-infected patients, Chlamydia pneumoniae was the sole agent detected in eight (2.5%) cases, and Chlamydia pneumoniae together with other infectious agents was detected in seven (2.2%) cases. Chlamydia pneumoniae is a possible cause of severe respiratory infection in Italian HIV-infected immunocompromised patients, and its presence must be suspected when patients do not respond to therapy with beta-lactam agents or to anti-Pneumocystis carinii treatment.