Comparison of Five Serologic Tests for Diagnosis of Acute Infections by Chlamydia pneumoniae

Abstract

Serology is often used to diagnose acute infections by Chlamydia pneumoniae. In this study paired sera from patients with acute respiratory tract infection during an epidemic of C. pneumoniae infections were examined by five different antibody tests. These tests were the complement fixation (CF) test, the microimmunofluorescence (MIF) test, a recombinant enzyme immunoassay (rEIA) (Medac) based on a recombinant lipopolysaccharide of chlamydia and measuring antibodies to a common chlamydial antigen, and two tests that utilize preparations of C. pneumoniae organisms, the SeroCp-EIA (Savyon) (with preserved lipopolysaccharide) and the LOY-EIA (Labsystems) (without this antigen). Both of the last two tests should measure specific antibodies to C. pneumoniae, although cross-reacting antibodies may also be detected by the SeroCp-EIA. Acute infection of C. pneumoniae was serologically confirmed in 44% of the cases by at least two different tests. Using an expanded "gold standard," i.e., the presence of significant reactions in at least two tests, the sensitivity of the CF test was 69%, that of the MIF test was 88%, that of the rEIA was 89%, that of the LOY-EIA was 96%, and that of the SeroCp-EIA was 92%. Specificity was high for all methods, but adjustments of diagnostic criteria were made to several of the tests. The basis for these adjustments and supportive data are presented. Infections of C. pneumoniae were detected in patients from 8 to 83 years of age. Two peaks in the incidence of such infections were observed: one among young teenagers and a second in adults 30 to 45 years of age, corresponding to parents of young teen-agers. The tests were equally sensitive in different age groups. Reinfections seemed to be rare.Serological diagnosis has been important to unravel the clinical manifestations of acute infections by Chlamydia pneumoniae. Isolation of the organism or detection of its nucleic acid by PCR has extended the diagnostic arsenal. These methods can provide early diagnosis, which might be helpful for accurate treatment. Serology based on analysis of paired sera will detect acute infection even after antibiotic treatment has been started and might be useful to discriminate between infections by C. pneumoniae and Chlamydia psittaci.The complement fixation (CF) test based on the common lipopolysaccharide (LPS) antigen of chlamydia has been used for many years to detect acute infections by C. psittaci. After C. pneumoniae was recognized and infection by this new agent could be confidently diagnosed by the microimmunofluorescence (MIF) test, many cases previously detected by the CF test and thought to be cases of ornithosis were found to in fact be infections by C. pneumoniae (12,18). Although the CF test can detect acute infections by C. pneumoniae, its sensitivity has been considered low for such infections, especially in reinfection (13). The MIF test has been of paramount importance to detect acute infections by C. pneumoniae and to describe the prevalence of such infections. The performance of the test dep...

Comparison of Eleven Commercial Tests for Chlamydia pneumoniae -Specific Immunoglobulin G in Asymptomatic Healthy Individuals

“…Several other studies have also shown that high anti-C. pneumoniae-specific IgG titers are common in healthy individuals (24,33,34,38). For the detection of an increase in the IgG titer, analysis of paired serum specimens in the same test run is necessary.…”

“…A recent study compared five serological tests for the diagnosis of acute infections caused by C. pneumoniae. The MIF and EIA from Labsystems, as well as the SeroCP ELISA and the rELISA, were included in the evaluation (38). Compared to the results of MIF, the specificities and sensitivities of the Labsystems EIA, the SeroCP ELISA, and the rELISA ranged from 89 to 95%.…”

Chlamydial Antibodies and Risk of Prostate Cancer

“…C. trachomatis-and C. pneumoniaespecific IgG antibodies were measured by the microimmunofluorescence method, which is considered a gold standard of chlamydial serology (31) with specificity estimated at 83% to 89% and sensitivity at 79% to 88% (32,33). Elementary bodies of pooled serovars BED (B-group), CJHI (C-group), and GFK (intermediate group) of C. trachomatis (Washington Research Foundation, Seattle, WA) and Kajaani 6 strain of C. pneumoniae were used as antigens.…”

Comparison of Three Commercially Available Peptide-Based Immunoglobulin G (IgG) and IgA Assays to Microimmunofluorescence Assay for Detection of Chlamydia trachomatis Antibodies

“…All three tests were performed according to the manufacturers' instructions. An in-house MIF assay was performed as described previously (9). Slides with antigens of C. trachomatis, C. psittaci, and C. pneumoniae (Labsystems OY) were used for this assay.…”