The correlation between positive rate of antibody or DNA and children's age with suspected Mycoplasma pneumoniae infection

Background Mycoplasma pneumoniae (MP) is a prevalent respiratory pathogen in children, with diagnosis typically relying on detecting MP DNA in nasal swabs or antibodies in blood samples. The relationship between MP DNA positivity and age in children is not well understood. We aimed to explore trends in MP DNA and antibody detection rates with age in a pediatric population. Methods This retrospective study analyzed data from 1,161 children under 14 years old hospitalized with suspected MP infection. The study included clinical presentations and laboratory tests, and all participants underwent chemiluminescence and nucleic acid detection for MP antibodies and DNA, respectively. We analyzed the relationship between age and MP DNA and antibodies in our study. Results The mean age of the children was 49.7 +/- 32.6 months. Laboratory data showed mild elevations in inflammatory markers and normal liver function tests, reflecting the generally moderate severity of MP infections. The study revealed that the positive rate of MP DNA was 9.0%, and it was negatively correlated with children's age (r = -0.21, P < 0.001). The positive rate of MP IgM antibody was 7.1%, and it was positively correlated with children's age (r = 0.18, P < 0.001). The positive rate of MP IgG antibody was 6.3%, and it was not correlated with children's age (r = 0.03, P = 0.36). Conclusion These results suggest that MP DNA detection identifies the MP infection earlier and more accurately than antibody detection and that younger children are more susceptible to MP infection than older children. Given the sensitivity and specificity of MP DNA found in young children in this study, it is recommended that it should be considered in routine clinical practice for early diagnosis and intervention.