Serum Interferon-γ Is Associated With Refractory Mycoplasma pneumoniae Pneumonia in Children

Background: Mycoplasma pneumoniae (MP) infection is associated with refractory severe clinical course, and steroid therapy has been suggested as an effective treatment for refractory MP pneumonia.Methods: A total of 53 patients with MP pneumonia and 9 patients with viral pneumonia patients were enrolled.Point mutations at residues 2063, 2064, and 2067 in domain V of 23S rRNA gene were analyzed, and serum levels of interferon (IFN)-, interleukin (IL)-6, TNF-, IL-10, and IL-1 were measured before and after steroid treatment.Results: There was no significant difference in serum cytokine concentrations between the MP pneumonia group and the viral pneumonia group.The A2063G point mutation was identified in 72% (18/25) of tested MP pneumonia patients.IFN- and IL-6 levels showed significant positive correlations with the duration of hospitalization, fever after admission and duration of steroid treatment.The macrolide-resistant MP (MRMP) group tended to have higher IFN- levels than the macrolide-sensitive MP group (P = 0.055).Notably, all patients (n = 9) with the highest IFN- levels (ranked in descending order) belonged to the MRMP group.Steroid treatment significantly reduced IFN- and IL-6 levels, suggesting effective modulation of excessive immune responses.LDH and AST levels were also correlated with IFN- and IL-6.Conclusion: Therefore, IFN- may serve as a valuable biomarker for predicting a refractory clinical course of MP pneumonia.In addition, LDH and AST levels, which showed the closest correlation to IFN- and IL-6, may also be proposed as indicators of disease severity.