Comparison of PCR, culture, and serological tests for diagnosis of Mycoplasma pneumoniae respiratory tract infection in children.

For diagnosis of Mycoplasma pneumoniae infection we compared two rapid tests, PCR and the immunoglobulin M immunofluorescence assay (IgM IFA), with culture and the complement fixation test (CFT), in a prospective study among 92 children with respiratory tract infection and 74 controls. Based on positivity of culture and/or CFT as the diagnostic criterion, nine patients (10%) were diagnosed with M. pneumoniae infection. All patients positive by culture were also positive by PCR. In all controls cultures, PCRs, and serological assays were negative, except in one with a positive IgM IFA. The IgM IFA had a low positive predictive value of 50%. Only a combination of PCR (seven patients) and CFT (seven patients) allowed diagnosis of all cases.