The diagnostic value of serological tests and real-time polymerase chain reaction in children with acute infection.

Background: This study set out to evaluate the clinical significance and diagnostic effectiveness of serological tests and real-time polymerase chain reactions (RT-PCR) in children of different age groups and disease durations infected with Mycoplasma pneumoniae (MP).

Methods: Pediatric patients with lower respiratory tract infection (LRTI) confirmed by polymerase chain reaction (PCR) were enrolled and subjected to bronchoalveolar lavage fluid PCR (BALF-PCR) for MP infection. The diagnostic values of the serum immunoglobulin M (IgM) test, paired sera immunoglobulin G (IgG) test, RT PCR applied to nasopharyngeal aspirates (NPA-PCR), and combined IgM and NPA-PCR test were evaluated.

Results: When BALF PCR was used as the gold standard, the MP positivity rate of combined IgM and NPA PCR was 78.85%in children aged 3-5 years. The positivity rates of IgM, NPA PCR, and combined IgM and NPA PCR in children older than 5 years were 71.21%, 72.72%, and 84.85%, respectively. The detection rate of combined IgM and NPA PCR was consistent with BALF PCR (Kappa =0.727). The MP positivity rates of combined IgM and NPA PCR at 1-2 weeks was as high as 91.11%, and was consistent with the BALF PCR (Kappa =0.756). Moreover, the positivity rates of IgM or NPA PCR at 2-3 weeks were 63.16%, and were consistent with each other (Kappa =0.771).

Conclusions: Combined IgM and NPA PCR is the optimal test to confirm MP infection among children aged 3-5 years in cases with a disease duration of less than2 weeks, and either NPA PCR or IgM is recommended for children older than 5 years with a disease duration of 2-3 weeks.

Keywords: Mycoplasma pneumoniae pneumonia (MPP); diagnosis; children; age; disease duration.