Abstract
OBJECTIVE: To investigate the impact of macrolide resistance and Mycoplasma pneumoniae DNA (MP-DNA) load in bronchoalveolar lavage fluid (BALF) on immune and inflammatory responses in children with Mycoplasma pneumoniae pneumonia (MPP). METHODS: This retrospective study included 190 hospitalized children with MPP who underwent bronchoscopy. Patients were classified as macrolide-resistant or macrolide-sensitive based on 23S rRNA mutation analysis. MP-DNA load and cytokines in BALF and inflammatory markers in blood were measured. MRMP patients were further stratified by MP-DNA load for subgroup analysis. RESULTS: Of 1029 children screened, 474 had MPP, and 190 who underwent bronchoscopy were analyzed. Macrolide-resistant mycoplasma pneumonia (MRMP) accounted for 73.2% of cases and was associated with longer fever duration and hospital stay, lower lymphocyte counts, higher BALF total cell counts and neutrophil proportions, and increased inflammatory cytokines. Among MRMP patients, those with high MP-DNA loads had greater BALF cytokine levels than those with low loads. MP-DNA load positively correlated with IL‑1β and IL‑6 levels. CONCLUSIONS: Macrolide resistance and high pathogen load are associated with enhanced airway inflammation and immune dysregulation in children with MPP. Early detection of resistance and quantification of pathogen load may guide timely antibiotic adjustment and improve clinical outcomes.