Chlamydophila pneumoniae diagnostics: importance of methodology in relation to timing of sampling

Abstract

The diagnostic impact of PCR-based detection was compared to single-serum IgM antibody measurement and IgG antibody seroconversion during an outbreak of Chlamydophila pneumoniae in a military community. Nasopharyngeal swabs for PCR-based detection, and serum, were obtained from 127 conscripts during the outbreak. Serum, drawn many months before the outbreak, provided the baseline antibody status. C. pneumoniae IgM and IgG antibodies were assayed using microimmunofluorescence (MIF), enzyme immunoassay (EIA) and recombinant ELISA (rELISA). Two reference standard tests were applied: (i) C. pneumoniae PCR; and (ii) assay of C. pneumoniae IgM antibodies, defined as positive if >or=2 IgM antibody assays (i.e. rELISA with MIF and/or EIA) were positive. In 33 subjects, of whom two tested negative according to IgM antibody assays and IgG seroconversion, C. pneumoniae DNA was detected by PCR. The sensitivities were 79%, 85%, 88% and 68%, respectively, and the specificities were 86%, 84%, 78% and 93%, respectively, for MIF IgM, EIA IgM, rELISA IgM and PCR. In two subjects, acute infection was diagnosed on the basis of IgG antibody seroconversion alone. The sensitivity of PCR detection was lower than that of any IgM antibody assay. This may be explained by the late sampling, or clearance of the organism following antibiotic treatment. The results of assay evaluation studies are affected not only by the choice of reference standard tests, but also by the timing of sampling for the different test principles used. On the basis of these findings, a combination of nasopharyngeal swabbing for PCR detection and specific single-serum IgM measurement is recommended in cases of acute respiratory C. pneumoniae infection.

Role of Chlamydia pneumoniae in community-acquired pneumonia in hospitalized Jordanian adults

“…In investigations without controls, C. pneumoniae DNA was found in 5% to 26% of patients diagnosed with acute respiratory infections such as CAP or bronchitis [20,39,41,42]. Miyashita and colleagues found that 8% of patients with acute respiratory disease had DNA in their respiratory samples, compared with 3% of asymptomatic controls [40].…”

“…Therefore, further investigations are necessary to elucidate the etiology of C. pneumoniae in CAP in Jordanian nationals. On the basis of previous findings [41,46,47], reliable, and sensitive diagnostic tests such as validated real-time PCR alone or combined with specific IgM-detecting method should be used to define cases of acute respiratory C. pneumoniae infection. Importantly, C. pneumoniae can be found in association with other CAP etiologic agents such as Streptococcus pneumoniae and Mycoplasma pneumoniae [13].…”

Elevated Serum Immunoglobulin G Titers Against Chlamydia pneumoniae in Primary Open-Angle Glaucoma Patients Without Systemic Disease

“…15,22,23 The serum antibodies to C. pneumoniae reach a diagnostic level 6 to 8 weeks after the exposure and infection of C. pneumonia, and the seropositivity remains for life. [24][25][26] The value (optical density) of seropositivity for C. pneumoniae is greater than 0.9 as reported in a paper written in Japanese using this ELISA kit. 27 Laboratory personnel were masked to clinical and demographic information on the patients.…”

Pneumonien – Wie viel Diagnostik muss sein?

“…Für die Detektion atypischer Pathogene sind die Tests validiert und die Ergebnisse so schnell verfügbar, dass sie auch therapeutisch relevant sind [24,25,26].…”

“…Wenn die ätio logische Diagnostik von atypischen Erregern erforderlich ist, sollten serologische Tests nicht als der einzige Routinetest durchgeführt werden. In diesem Fall ist die Kombination aus der Bestimmung von IgM-Antikörpern und einer PCR der Ansatz mit der höchsten Sensitivität [21,25,26].…”