ELISA-VIDITEST anti-Chlamydia pneumoniae IgG kit is intended for the qualitative detection of anti-Mycoplasma pneumoniae anibodies in human serum and human plasma. The laboratory diagnostic procedures in C. pneumoniae infections involve an isolation of the pathogen from cell culture, direct antigen detection, nucleic acid amplification tests and serology tests. Difficulties in sample collection and inaccessibility of culture and non-culture methods have made serology the method of choice. Besides the microimmuno-fluorescence method (MIF), antibodies to C. pneumoniae can also be detected by an enzyme immunoassay. Primary chlamydial infection is characterized by the predominant IgM response within 2 to 4 weeks and the delayed IgG and IgA response within 6 to 8 weeks. After the acute C. pneumoniae infection IgM antibodies usually decrease and become undetectable in 2 to 6 months. IgG antibody titres decrease slowly, whereas IgA antibodies tend to disappear rapidly. When primary chlamydia infection is suspected, the detection of IgM is highly diagnostic. However, in recurrent or chronic infections the prevalence of IgM is low and therefore the absence of IgM does not necessarily exclude an on-going infection. In reinfections, IgG and IgA levels rise quickly. IgA antibodies have shown to be a reliable immunological marker of primary, chronic and recurrent infections. These antibodies usually decline rapidly to baseline levels following treatment and eradication of the chlamydia infection. The persistence of the elevated IgA antibody titres is generally considered as the sign of chronic infection. The purified, homogeneous antigen is fixed to each well of the microtiterstrips. Specific antibodies present in the patient's sample are bound during the first incubation step. After removing unbound material by washing, the presence of the specific antibodies is detected using anti-human IgG conjugate during the second incubation. The unbound peroxidase conjugate is then removed and TMB substrate is added, resulting in the development of a blue colour. The enzyme reaction is terminated by addition of the stop solution. The intensity of the colour is proportional to the concentration of the antibodies in the sample.