Mycoplasma pneumoniae pneumonia in children: Clinical characteristics and risk factors of refractory pneumonia by age

Purpose: It is thought that Mycoplasma pneumoniae infection is more prevalent and causes more severe pneumonia in school-age children and young adults than in preschool children; however, recent studies suggest that the infection may be underdiagnosed and more severe in preschool children. This study investigated the clinical characteristics of Mycoplasma pneumoniae pneumonia (MPP) and the risk factors of refractory MPP (RMPP) by age. Methods: We retrospectively reviewed the medical records of 353 children admitted due to MPP from January 2015 to December 2016. Demographics, clinical information, laboratory data and radiological findings were collected from all patients in this study.The patients were divided into 2 groups by the age of 6 years. Also, both preschool (<6 years old) and school-age (>= 6 years old) children were divided into RMPP and non-RMPP patients. Results: Total febrile days, febrile days before admission and the duration of macrolide antibiotic therapy were significantly longer in school-age children than in preschool children. School-age children had significantly greater risk of lobar consolidation (P=0.036), pleural effusion (P=0.001) and extrapulmonary complications (P=0.019). Necrotizing pneumonia and bronchiolitis obliterans tended to occur more frequently in preschool children than in school-age children. In both preschool and school-age children, lactate dehydrogenase (LDH) levels were significantly higher in RMPP patients than in non-RMPP patients. In preschool children, LDH >722 IU/L (odds ratio [OR], 3.02; 95% confidence interval [Cl], 1.44 -6.50) and ferritin >177 ng/mL (OR, 5.38; 95% Cl, 1.61-19.49) were significant risk factors for RMPP, while LDH >645 IU/L (OR, 4.12; 95% Cl, 1.64-10.97) and ferritin >166 ng/mL (OR, 5.51; 95% Cl, 1.59-22.32) were so in school-age children. Conclusion: Clinical features of MPP were significantly different between preschool and school-age children. LDH and ferritin may be significant factors of RMPP in preschool and school-age children.