Macrolide-Resistant Mycoplasma pneumoniae Rebound and Fungal Colonization Patterns in Children After Pandemic Interventions: An Ecological Cohort Study

We characterized respiratory pathogen shifts across 71,509 pediatric respiratory admissions (2016–2023) at a tertiary children’s hospital in Beijing, China, spanning the complete COVID-19 non-pharmaceutical intervention cycle. Mycoplasma pneumoniae detection rebounded 10.2-fold, from 5.3% during late intervention to 54.2% after reopening, exceeding the pre-pandemic baseline (25.3%); macrolide resistance reached 98.8%. Among categorized respiratory fungal records, 86.5% were Candida species, and pharmacologic immunosuppression—rather than autoimmune disease itself—was linked to both fungal record burden and detection of fungi with invasive potential. First-time bronchiolitis obliterans admissions showed 47.7% MP positivity versus 23.0% in non-BO admissions, with positivity highest in the 30 days before BO diagnosis (63.1%) and declining thereafter. Co-infection among fully tested children rose from 11.5% to 28.2%. While macrolide resistance was not the primary driver of the BO increase, the near-universal resistance among rebounding MP strains (98.8%) significantly complicated clinical management. Postintervention rebound was dominated by macrolide-resistant MP with increased polymicrobial co-detection, informing empiric treatment and fungal stewardship decisions.