DIAGNOSIS OF CHLAMYDIA-PNEUMONIAE INFECTION IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE BY MICRO-IMMUNOFLUORESCENCE AND ELISA

The incidence of Chlamydia pneumoniae infection was determined in pati ents with chronic obstructive pulmonary diseases (COPD) by prospective serial serology. Chlamydia-specific IgG, IgM and IgA antibodies were detected with a recombinant DNA lipopolysaccharide (LPS) ELISA as well as with a micro-immunofluorescence (MIF) assay with C. pneumoniae ele mentary bodies, From 271 consecutive COPD patients who visited the out patient clinic of the department of pulmonary diseases (211 males, 60 females, age range 34-88 years, mean age 66 SD 10 years), blood sample s (n = 1058) were taken every 2-7 months; the observation period range d from 3 to 19 months (mean 15 SD 4), The prevalence of chlamydial IgG was 72% with the MIF and 53% with the rDNA LPS ELISA, More than 90% o f the COPD patients had no significant changes in their chlamydia-spec ific IgG, IgA and IgM titres in either test during the observation per iod, Seven (3%) patients had MIF results indicating acute C. pneumonia e infection during their surveillance period, of whom five were confir med by rDNA LPS ELISA, Eleven (4%) additional patients were infected d uring observation, as determined by rDNA LPS ELISA only, These patient s had significantly elevated C. pneumoniae-specific IgG and IgA MIF ti tres; as compared with the patients without infection, All 18 patients with serological evidence of acute infection during their surveillanc e period were re-tested in a commercial MIF test that can distinguish between C. pneumoniae, C. trachomatis and C. psittaci LPS-specific ant ibodies, but no evidence of C. trachomatis or C. psittaci infection wa s found, The incidence of chlamydial infection was 2.2 and 5.3/100 per son-years, when diagnosed by MIF and rDNA LPS ELISA, respectively, It is concluded that the rDNA LPS chlamydia assay may currently be the mo st sensitive serological tool for diagnosing recent respiratory chlamy dia infections and that C. pneumoniae infection occurs frequently in C OPD patients.