Diagnosis of Mycoplasma pneumoniae pneumonia in children

We evaluated a commercial immunoglobulin M (IgM)-capture immunoassay for the detection of Mycoplasma pneumoniae infections in 278 pediatric patients with community-acquired, radiographically defined pneumonia. Acute- and convalescent-phase serum samples were collected from all patients and were tested for M. pneumoniae-specific IgM and IgG antibodies by Platelia enzyme immunoassays (Sanofi Diagnostica Pasteur, Marnes la Coquette, France). Nasopharyngeal aspirates (NPAs) were collected at the time of admission to the hospital. A total of 227 NPAs were subjected to the detection of M. pneumoniae DNA by PCR, and 191 NPAs were cultured by using the Pneumofast kit (International Mycoplasma, Signeswere, France). Southern hybridization of PCR products and the IgM test with solid-phase antigen (Serion Immunodiagnostica, Würzburg, Germany) were used for additional confirmation of a positive result, which required agreement of at least two different methods. A total of 24 (9%) confirmed diagnoses of mycoplasma infection were made, 5 (21%) of which were in children <5 years of age. Of the positive children, 24 of 24 (sensitivity, 100%) were positive by the IgM-capture test with convalescent-phase serum, 19 of 24 (79%) were positive by the IgM-capture test with acute-phase serum, 19 of 24 (79%) were positive by IgG serology, 10 of 20 (50%) were positive by PCR, and 8 of 17 (47%) were positive by culture. An additional 5 (of 254) children were positive by the Platelia IgM test alone (specificity, 98%). When the PCR with Southern hybridization result was combined with the IgM-capture test result with the acute-phase sera, the sensitivity of rapid laboratory diagnosis increased to 95%. In conclusion, the IgM serology test was the single most valuable tool for the diagnosis of M. pneumoniae pneumonia in children of any age.