Correlation between serum Mycoplasma pneumoniae antibodytiters and common clinical indicators in children

OBJECTIVE To investigate the association between Mycoplasma pneumoniae antibody (MP-Ab) titers in children and common laboratory indicators such as immunoglobulin E (IgE), C-reactive protein (CRP), procalcitonin (PCT), eosinophils (EOS), platelets (PLT), lymphocyte count (LYM) and basophil count (BAS). METHODS A retrospective analysis was conducted on the medical records and laboratory data of 4 458 children with MP infection treated at the Second Affiliated Hospital of Anhui Medical University from Jan. 2020 to Dec. 2024. Based on passive agglutination MP-Ab titers, the patients were divided into groups: ≤1∶80 (n=1 134), 1∶160 (n=1 115), 1∶320 (n=720) and ≥1∶640 (n=1 489). Subgroups were further categorized by age (≤5 years or >5 years). Linear trend tests analyzed the trend relationship between MP-Ab titers and common indicators, while Spearman's method was applied to assessed correlations. RESULTS For children aged ≤5 years, MP-Ab titers showed a positive linear correlation with CRP (r_s=0.174, F_trend=53.313, P＜0.001), EOS (r_s=0.078, F_trend=5.203, P=0.023) and PLT (r_s=0.090, F_trend=16.959, P＜0.001), and a negative linear correlation with PCT (r_s=-0.104, F_trend=16.521, P＜0.001) and LYM (r_s=-0.071,F_trend=13.190, P＜0.001). As MP-Ab titers increased, CRP, EOS and PLT exhibited an upward trend (all P＜0.05), whereas PCT and LYM showed a downward trend (all P＜0.05). For children aged >5 years, MP-Ab titers showed a linear positive correlation with CRP (r_s=0.119,F_trend=20.004, P＜0.001), LYM (r_s=0.036, F_trend=4.581, P=0.033), MON (r_s=0.101, F_trend=14.931, P＜0.001), EOS (r_s=0.106, F_trend=21.352, P＜0.001), BAS (r_s=0.098, F_trend=10.488, P=0.001) and PLT (r_s=0.210, F_trend=49.577, P＜0.001). As MP-Ab titers increased, CRP, LYM, MON, EOS, BAS and PLT exhibited an upward trend (all P＜0.05). CONCLUSIONS In addition to MP-Ab titers, clinicians should also pay attention to age stratification, CRP concentration and changes in routine blood tests during the diagnosis and treatment of MP infection.