COMPARISON OF 2 SEROLOGICAL METHODS AND A POLYMERASE-CHAIN-REACTION ENZYME-IMMUNOASSAY FOR THE DIAGNOSIS OF ACUTE RESPIRATORY-INFECTIONS WITH CHLAMYDIA-PNEUMONIAE IN ADULTS

Chlamydia pneumoniae is a common respiratory tract pathogen, Serologic al methods currently used for the diagnosis of C. pneumoniae infection lack specificity, give ambiguous results from a single serum sample a nd often provide only a retrospective diagnosis. A prospective study w as undertaken to assess whether PCR could be a useful addition to the serological techniques routinely practised for diagnosis. This study i nvestigated 68 adult patients with a diagnosis of acute respiratory in fection. Acute and convalescent serological determination of antibodie s to C. pneumoniae were performed by means of an rELISA test and a mic ro-immunofluorescence (MIF) test. Nasopharyngeal aspirates or bronchoa lveolar lavage specimens and bronchial aspirates obtained from the 68 patients were evaluated by PCR-enzyme immunoassay (PCR-EIA) for the pr esence of C. pneumoniae and by immunofluorescence assay and cell cultu re for virus identification. Mycoplasma pneumoniae serology was also p erformed. Eight patients (11.8%) were positive by either rELISA or PCR -EIA, or both, with an infection rate of 5 (18.5%) of 27 in patients w ith community-acquired pneumonia, 2 (9%) of 22 in asthmatic patients a nd 1 (5%) of 19 in patients with an exacerbation of chronic obstructiv e pulmonary disease. Serological evidence of acute infection was found in four of these patients with the rELISA test and in three others wi th the MIF test. PCR-EIA detected C, pneumoniae DNA in four specimens, but there were concordant results with both rELISA and PCR-EIA in onl y one patient. A positive PCR-EIA was also obtained in a patient who d id not show an antibody response in acute serum. The discrepancy betwe en serological and PCR-EIA results reflects the difficulties in routin e laboratory diagnosis of C. pneumoniae infection and the necessity fo r further studies with optimised techniques.