Medical expert of the article
New publications
IgG and IgM antibodies to Chlamydia pneumoniae
Last reviewed: 04.07.2025
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Diseases caused by Chlamydia pneumoniae. IgG and IgM antibodies to Chlamydia pneumoniae
Chlamydia pneumoniaecauses respiratory tract damage in humans. In most cases (70% of those infected), the infection is asymptomatic, in other cases - according to the nasopharyngeal and pneumonic forms of lesions. The duration of the incubation period is quite long (not precisely established). Asymptomatic carriage can last up to 1 year or more, which in some cases leads to the appearance of relapses and exacerbations of chronic asthmatic bronchitis, bronchial asthma, chronic obstructive pulmonary disease. After the disappearance of clinical signs of acute disease, Chlamydia pneumoniae can be isolated by the culture method from nasopharyngeal washes even after 12 months. Pneumonia caused by Chlamydia pneumoniae does not have pathognomonic symptoms. Cases with a severe and persistent course are often observed.
Diagnosis of infections caused by Chlamydia pneumoniae causes certain difficulties, primarily related to the lack of simple and reliable laboratory methods for detecting intracellular parasites and the characteristics of the patient's immune response to the pathogen.
Any infection caused by parasites of the genus Chlamydia is accompanied by the rapid formation of antibodies to the genus-specific lipopolysaccharide antigen for all parasites; they can be detected by microimmunofluorescence and ELISA methods.
IgM antibodies to Chlamydia pneumoniae, formed during primary infection and confirming the etiologic diagnosis of the disease even with a single study, can be detected in the indirect immunofluorescence reaction or ELISA (sensitivity - 97%, specificity - 90%). However, rational antibacterial therapy can prevent the formation of antibodies and lead to negative test results. During reinfection, the titer of IgM antibodies to Chlamydia pneumoniae increases insignificantly, so the assessment of the test results is controversial. IgG and IgA antibodies, when using ELISA, are detected later than IgM antibodies during primary infection. Their combined detection in the patient's blood indicates acute and/or manifest chronic infection. IgA antibodies serve as markers of reinfection, since they are present in the blood for a short period of time. IgG antibodies have diagnostic value only when examining paired sera. An increase in the antibody titer makes it possible to assume the presence of an acute or manifest infection. The diagnostic sensitivity of IgG AT detection for establishing the etiology of the disease is 99%, specificity is 95%, for IgA antibodies - 95% and 93%, respectively.
For detection of Chlamydia pneumoniae antigensIn oropharyngeal or bronchial lavage, the ELISA, indirect immunofluorescence, and PCR methods are used. An optimal culture method for isolating Chlamydia pneumoniae has not yet been developed.
Any serological test performed without the simultaneous use of PCR, as well as in the absence of paired sera, is retrospective and not diagnostic in nature.
[