Serological study on Chlamydophila pneumoniae in patients with community-acquired pneumonia.

This study aimed to evaluate the incidence of Chlamydophila pneumoniae antibodies in patients with community acquired pneumonia (CAP) by a new ELISA test (EIA CP-IgG, IgA, IgM--Eurospital, Trieste, Italy). From January 1999 to July 2001 141 patients with clinical signs of CAP were enrolled in sixteen Italian Hospitals. Specific IgM and IgG antibodies anti-C. pneumoniae in serum and IgA in both serum and sputum were detected. At a primary inspection (time T-0) serum and sputum samples were taken from 115/141 patients, whereas serum was collected from only 100/141 patients after 30 days (time T-30). At T-0 24/115 (20.8%) patients showed serological markers thus suggesting an acute C. pneumoniae infection. In 23/24 patients the overall serological pattern found at T-0 was confirmed at T-30. In 32/115 patients (27.8%) serological markers of C. pneumoniae past infection were found positive and were confirmed 30 days later. These data support the role of C. pneumoniae as an important aetiological agent of CAP throughout different geographic areas of Italy. The test was suitable for the laboratory diagnosis of C. pneumoniae infection. In particular, the presence of specific IgA anti- C. pneumoniae in both serum and sputum proved useful to define different stages and evolution of infection.