Relevance of serology for Mycoplasma pneumoniae infection among children with persistent cough.

BACKGROUND Mycoplasma pneumoniae is an important cause of upper and lower respiratory tract infections. Cough and tracheobronchitis are the commonest features of M. pneumoniae infection but diagnosis based on clinical symptoms that may be due to other respiratory pathogens is impossible. Thus laboratory testing for M. pneumoniae is particularly important. Correct and rapid diagnosis of M. pneumoniae infections is of prime importance to introduce appropriate antibiotic treatment. OBJECTIVES Evaluation of the incidence of IgM and IgG antibodies specific to M. pneumoniae among children with pneumonia and/or chronic cough. MATERIAL AND METHODS Serum samples from 148 children with a history of chronic cough (lasting at least one month), recurrent respiratory tract infections, allergic rhinitis, and/or inflammatory changes on X-chest ray. First, all sera were screened for specific anti-M. pneumoniae antibodies using agglutination test following the detection of specific IgM and IgG anti-M. pneumoniae antibodies using immunoenzymatic assays. RESULTS Out of the 148 serum samples, 57 (38.5%) gave positive screening results. However, the presence of M. pneumoniae-specific IgM and/or IgG antibodies was confirmed by immunoenzymatic assays in only 30 (52.6%) of these 57 positive samples. These results indicated that in as many as 27 (47.4%) out of the 57 serum samples screened, false-positive results occurred. CONCLUSIONS Evaluation of acute- and convalescent-phase sera is necessary to make possible accurate interpretation of the serological testing results.