Background: Mycoplasma pneumoniae  pneumonia (MPP) is a common community-acquired pneumonia (CAP) in children, which may become refractory MPP (RMPP) to treatment.
Objective: The purpose of this study was to evaluate the clinical utility of measuring serum interleukin (IL)-17A to predict RMPP.
Patients and Methods: A retrospective clinical study at a single pediatric center included a review of the medical records of all children hospitalized for CAP between November 2015 and October 2019. The diagnosis of MPP was based on clinical presentation, chest radiography, and measurement of serum anti-Mycoplasma  immunoglobulin IgM antibody titer using the microparticle agglutination method or sputum samples for Mycoplasma pneumoniae  by PCR. Serum levels of IL-18 and IL-17A were determined by ELISA.
Results: Of the 625 children diagnosed with CAP, there were 154 children with MPP and without underlying diseases who were divided into a non-refractory MPP (NRMPP) group (n = 109) and a RMPP group (n = 45). The RMPP group had a higher incidence of tachypnea, cyanosis, hypoxia, segmental or lobar pneumonia, pleural effusion, and a longer period of hospitalization compared with NRMPP group (all P -values < 0.05). A serum IL-17A level above 10.8 pg/mL was a predictor for RMPP: area under the curve (AUC) 0.822; standard error (SE) 0.039; 95% confidence interval (CI) 0.746– 0.897; diagnostic sensitivity and specificity of 77.8% and 77.1%, respectively. An LDH level above 436.5 IU/L and an IL-18 level above 464.5 pg/mL were the second most useful markers for RMPP: AUC 0.775, 0.775; SE 0.038, 0.039; 95% CI 0.700– 0.850, 0.698– 0.852; sensitivity 77.8%, 82.2%; specificity 62.4%, 59.6%; respectively.
Conclusion: This preliminary study of MPP in a pediatric population has shown that measurement of serum IL-17A may be a useful marker for the predictor of RMPP.
Keywords: Mycoplasma pneumoniae , pneumonia, refractory pneumonia, interleukin-17A