Chlamydia pneumoniae pneumonia in hospitalized patients - Clinical characteristics and diagnostic value of polymerase chain reaction detection in BAL

Study objective: To evaluate the incidence and clinical characteristics of Chlamydia pneumoniae infection as detected by polymerase chain reaction (PCR) and culture of BAL in hospitalized patients with pneumonia, HN-infected persons, and control subjects. Design: Prospective, comparative clinical study. Setting: University hospital medical center. Patients: Fifty-seven hospitalized patients with acute lower respiratory tract infection (group 1); 47 HIV-positive patients (group 2); 100 patients with noninfectious bronchopulmonary disorders (group 3). Interventions: BAL was performed in all patients at hospital admission for diagnostic purposes, In addition to semiquantitative bacterial and fungal culture, isolation and detection of C pneumoniae were performed by cell culture and PCR of the lavage fluid. Measurements and results: C pneumoniae was detected in 16% of group 1, 13% of HIV-positive persons, and 0% of control subjects. The sensitivity of chlamydial culture was much lower as compared with PCR (4 vs 15 cases). In contrast to group 1, in the HN-positive patients, acute respiratory symptoms were not always present, and in 3 of 6 cases, copathogens were found in the BAL. BAL differential cell counts disclosed a significant lymphocyte elevation mostly due to the CD8 subset (group 1: 15% vs 5%; group II: 18.5% vs 4%; C pneumoniae positive vs negative cases, respectively). Conclusions: C pneumoniae is frequently detected in the BAL of hospitalized patients with pneumonia as sole pathogen. PCR detection is highly specific and far more sensitive than cell culture. Asymptomatic carriage seems to be uncommon in immunocompetent patients, but does occur in HIV-positive patients. A lymphocytic alveolitis is frequently found by BAL cytologic study and may represent a T-cell response to chlamydial infection in the lower respiratory tract.