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)-γ, interleukin (IL)-6, TNF-α, IL-10, and IL-1β 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-γ 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-γ levels than the macrolide-sensitive MP group (P = 0.055). Notably, all patients (n = 9) with the highest IFN-γ levels (ranked in descending order) belonged to the MRMP group. Steroid treatment significantly reduced IFN-γ and IL-6 levels, suggesting effective modulation of excessive immune responses. LDH and AST levels were also correlated with IFN-γ and IL-6.

CONCLUSION

Therefore, IFN-γ 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-γ and IL-6, may also be proposed as indicators of disease severity.