[Prevalence of Chlamydia pneumoniae infection among pneumonias in a sample of Spanish hospital population].

Background: The importance of Chlamydia pneumoniae as a cause of respiratory tract infection in humans has been shown recently. There is no data in Mediterranean countries about C. pneumoniae infection.
Methods: We tested acute and convalescent serum collected from 103 Spanish pneumoniae patients from 1979 to 1987. The microimmunofluorescent test (MIF) with C. pneumoniae and other Chlamydia antigens to exclude cross reactions was used. Serological evidence of current infection was a fourfold rise in IgG antibody titer o titer 1/6 in the IgM serum fraction in the MIF test.
Results: The mean age of the patients was 52 years (typical deviation 18, with an age range of 13 to 83) and 75% were male. Serological data of recent infection was found in four of the 103 patients and 59 had antibodies in the IgG fraction indicative of previous infection.
Conclusions: These finding show that C. pneumoniae is associated with pneumonia in Spain and that there is a wide contact with this agent in the patient population with lower respiratory tract infection.