Comparison of real-time polymerase chain reaction and serological tests for the confirmation of Mycoplasma pneumoniae infection in children with clinical diagnosis of atypical pneumonia

J Microbiol Immunol Infect. 2014 Apr;47(2):137-44. doi: 10.1016/j.jmii.2013.03.015. Epub 2013 May 29.


Background: Mycoplasma pneumoniae is a common pathogen of respiratory tract infection in children, and its correct and rapid diagnosis is a clinical challenge. Real-time polymerase chain reaction (RT-PCR) has been used frequently for the detection of this pathogen.

Materials and methods: Medical records from all children with a clinical diagnosis of mycoplasma pneumonia and whose respiratory samples were tested for M. pneumoniae (using RT-PCR) during 2011 were reviewed retrospectively. We compared the sensitivity and specificity of serological assays versus those of RT-PCR for diagnosis of M. pneumoniae infections. We also reviewed retrospectively clinical characteristics, and laboratory and imaging findings of children with laboratory evidence of M. pneumoniae infection.

Results: In 2011, 290 children were diagnosed to have mycoplasma pneumonia clinically and had their respiratory samples tested for M. pneumoniae by RT-PCR. Fifty-four children (19%) had a positive result. Meanwhile, 63% (182/290) of these children also underwent serological tests, out of whom 44 (24%) were found to be positive for immunoglobulin M (IgM). Using PCR as a gold standard, M. pneumoniae IgM assay was found to show a sensitivity of 62.2% and a specificity of 85.5%. Positive and negative predictive values of IgM were 52.3% and 89.9%, respectively. In M. pneumoniae IgM-positive children, a negative PCR result was associated with more coinfection by other pathogens and longer duration of prehospitalization fever. Bacterial loads of M. pneumoniae were not correlated with clinical outcomes.

Conclusion: The majority of clinically diagnosed mycoplasma pneumonia was unconfirmed. Mycoplasma pneumoniae IgM has poor sensitivity and a positive predictive value. Interpretation of Mycoplasma pneumoniae IgM should be done with caution.

Keywords: Immunoglobulin M; Mycoplasma pneumoniae; Polymerase chain reaction.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • Diagnostic Tests, Routine / methods*
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Mycoplasma pneumoniae / genetics
  • Mycoplasma pneumoniae / immunology
  • Mycoplasma pneumoniae / isolation & purification*
  • Pneumonia, Mycoplasma / diagnosis*
  • Predictive Value of Tests
  • Real-Time Polymerase Chain Reaction / methods*
  • Retrospective Studies
  • Sensitivity and Specificity
  • Serologic Tests / methods