Comparison of SeroMP IgA with four other commercial assays for serodiagnosis of Mycoplasma pneumoniae pneumonia.

Acute phase serum samples from 23 patients with Mycoplasma pneumoniae pneumonia were examined for specific antibodies with microparticle agglutination (MAG)-assay, complement fixation (CF)-test, IgM-specific ELISA, and Immunocard-based IgM-EIA. A novel 3-h IgA-ELISA (SeroMP-IgA) was tested to assess its diagnostic value. For MAG, CF, IgM-ELISA, card-based IgM-EIA, and IgA-ELISA positive results were obtained in 87%, 87%, 91%, 87%, and 100%, respectively. Overall concordance was 78%. Specificity testing of 46 healthy blood donors revealed an optimal diagnostic cut-off range of 22-30 IgA-ELISA binding units (BU)/mL resulting in 91%-100% specificity and 100%-96% sensitivity for serologic diagnosis of acute M. pneumoniae infection.