Antibodies to Mycoplasma pneumoniae in the blood
Last reviewed: 23.04.2024
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Serological diagnosis is based on the detection of titer of antibodies to Mycoplasma pneumoniae in serum. The most widely used method was ELISA.
When using ELISA, antibodies of IgA, IgM and IgG classes can be determined. This method is more sensitive and specific (92% and 95% respectively) than others. The titers of antibodies IgM and IgG should be determined in the acute period of the disease and after 2-4 weeks. Antibodies IgM appear during the first week of the disease and disappear after recovery, but in some cases can persist in the blood to 1 year. The titer of IgG antibodies begins to increase somewhat later than IgM, but it remains elevated longer. The IgM titer above 1:10 or 4-fold increase in levels of IgA and / or IgG-AT in paired sera indicates an ongoing infection. Considering the fact that IgM antibodies relatively quickly disappear from the blood, in some cases it is sufficient to detect them in a single sample of serum for the diagnosis of acute infection. The titer of IgA-AT in elderly patients rises more significantly than IgM antibodies, which must be taken into account when diagnosing the infection. Upon recovery, IgM antibodies may not be detected in serum, and IgA- and IgG-AT content is significantly reduced. Reinfection is accompanied by a rapid rise in the titer of IgA and / or IgG-AT. The time of 4-fold increase in the titer of antimycoplasma antibodies in the sequential study of blood samples taken in the acute period of the disease and during the convalescence is 3-8 weeks.
Specific IgM antibodies to Mycoplasma pneumoniae are found in 80% of patients on the 9th day after the onset of the first symptoms of the disease.
On day 7-8, IgM antibodies are detected in 88% of patients under the age of 20 years and in 40% of older patients. In patients with mycoplasma infection older than 60 years, an increase in IgM antibody titer may not be.
Simultaneous detection of antibodies IgM and IgG allows to detect up to 99% of all mycoplasma infections (primary and reinfection), and the study of IgM antibodies alone - 78% of primary diseases.
The definition of antibodies to Mycoplasma pneumoniae is used to diagnose mycoplasmal infection in chronic inflammatory diseases of the lungs, secondary immunodeficiency states.
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