title: Evaluation of serological methods in the diagnosis of Chlamydia pneumoniae pneumonia during an epidemic in Finland.
abstract: A complement fixation (CF) test, a micro-immunofluorescence (micro-IF) test and an enzyme immunoassay (EIA) using Re-lipopolysaccharide as antigen were compared in the diagnosis of chlamydial infection in 136 mainly elderly patients hospitalized with community-acquired pneumonia during a Chlamydia pneumoniae epidemic in Finland in 1986-1987. Chlamydial pneumonia was diagnosed in 58 (42.6%) of the 136 pneumonia patients; 44 (75.9%) of them could be shown by micro-IF to be caused by Chlamydia pneumoniae, three by Chlamydia psittaci and four by Chlamydia spp. Only 5 (11.4%) of 44 patients with Chlamydia pneumoniae pneumonia were IgM-positive, indicating that the majority of cases were reinfections. In this population of mainly elderly patients the CF test was insensitive, being positive in only 6 (10.3%) of 58 cases of chlamydial pneumonia. The EIA detected 72.4% of cases and micro-IF 87.9% of cases (including infections with Chlamydia pneumoniae, Chlamydia psittaci and Chlamydia spp.). In the EIA 77% of positive cases were positive in serum samples taken a week apart, whereas the corresponding figure for micro-IF was 50%. In micro-IF the measurement of IgA antibody levels is recommended and IgM-positive sera should be retested after removal of IgG antibody to avoid false-positive findings due to presence of rheumatoid factor. The collection of a third serum sample, for instance one month after onset, is also recommended, since half of the patients showed a diagnostic response in the micro-IF only in the sera taken one month apart.
authors.affiliation: Department of Virology, University of Helsinki, Finland.
authors.forename: M R
authors.initials: MR
authors.lastname: Ekman
authors.forename: M
authors.initials: M
authors.lastname: Leinonen
authors.forename: H
authors.initials: H
authors.lastname: Syrjälä
authors.forename: E
authors.initials: E
authors.lastname: Linnanmäki
authors.forename: P
authors.initials: P
authors.lastname: Kujala
authors.forename: P
authors.initials: P
authors.lastname: Saikku
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000453:epidemiology; D016993:Chlamydophila pneumoniae / Q000276:immunology / Q000302:isolation & purification*; D003168:Complement Fixation Tests; D005260:Female; D005387:Finland / Q000453:epidemiology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000175:diagnosis*; D012698:Serologic Tests
chemical_list: D000907:Antibodies, Bacterial