Immune response to M. pneumoniae
In primary infections specific IgM and IgA antibodies use to increase significantly between 1-2 weeks after onset of symptoms, followed by IgG antibodies. In reinfections IgM antibodies are rarely found, here, the presence of elevated IgA and IgG antibodies is indicative. IgM is the decisive antibody concerning M. pneumoniae infections in children whilst in adults IgA is more pronounced.

Diagnostics
Serological diagnosis is commonly performed with the complement fixation test (CFT) and the particle agglutination test (PAT). They are partly time-consuming assays which cannot discriminate between antibody isotypes. Both test systems detect also IgG antibodies which may provide false positive results due to past infections.
As IgM antibodies may persist for more than one year after infection, detection of specific IgM alone does not accurately indicate primary infections. Primary infection and reinfection may be distinguished by the presence of IgM and IgA in primary infections and by the presence of elevated IgA and IgG in the absence of specific IgM in reinfections.
An ELISA which is based on recombinant, immunodominant M. pneumoniae-specific proteins, which is characterized by good sensitivity and specificity, and which allows discrimination of the antibody isotypes will overcome the shortcomings of CFT and PAT. The crucial factor for a specific and sensitive ELISA is the antigen. The important immunogenic proteins of M. pneumoniae are principally distributed all over the surface of the pathogen. Out of the more than 10 known immunogenic proteins, the P1 (170 kDa) protein is of predominant usefulness, a fact, that had been considered by medac.


Indication for M. pneumoniae serology with Mycoplasma pneumoniae-IgG-, IgA-, IgM-ELISA medac

· Diagnostic differentiation between M. pneumoniae infections and other pathogens (viruses, other bacteria)
· Identification of M. pneumonia-triggered acute infections and reinfections of the upper and lower respiratory tract
· Seroepidemiological investigations

The following test systems are available:)
· Mycoplasma pneumoniae-IgG- and IgA-ELISA medac (quantitative)
· Mycoplasma pneumoniae-IgM-ELISA medac (qualitative)


For test procedure and test performance please refer to the corresponding Directions for use.