Pathogen Spectrum and Lobar Distribution of Consolidation in Pediatric Post-Infectious Bronchiolitis Obliterans: A 10-Year Retrospective Study

Background Post-infectious bronchiolitis obliterans (PIBO) is a chronic pediatric airway disease characterized by fixed airflow limitation and recurrent infectious exacerbations. Empiric antibiotic treatment during exacerbations is often broad because rapid, actionable signals of bacterial etiology are limited. We investigated whether the lobar distribution of consolidation on high-resolution computed tomography (HRCT) is associated with bronchoalveolar lavage fluid (BALF) bacterial findings in children with established PIBO. Methods We retrospectively reviewed children with established PIBO hospitalized at Guangzhou Women and Children’s Medical Center (January 2015-June 2025) who developed HRCT-confirmed pulmonary consolidation during an acute infectious exacerbation and underwent bronchoscopy with BALF culture. Consolidation distribution by lobe was assessed independently by a pediatric radiologist and a respiratory physician blinded to microbiology, and patterns were compared between culture-positive and culture-negative episodes. Results Forty-seven children met inclusion criteria; 33 (70.2%) had positive BALF cultures. Haemophilus influenzae (39.4%), Staphylococcus aureus (27.3%), Streptococcus pneumoniae (24.2%), and Moraxella catarrhalis (21.2%) were the most frequent isolates. Middle and/or lower-lobe consolidation was more common in culture-positive than culture-negative episodes (93.9% vs 50.0%; OR 15.5, 95% CI 2.6–91.2), whereas upper-lobe consolidation was more frequent in culture-negative episodes (64.3% vs 24.2%; OR 5.6, 95% CI 1.5–21.8). S. aureus showed more diffuse lobar involvement, while other common pathogens predominantly involved the middle/lower lobes. Conclusions In pediatric PIBO exacerbations, lobar consolidation patterns on HRCT align with BALF bacterial findings and may help prioritize sampling and support more targeted empiric antibiotic choices and de-escalation within antimicrobial stewardship strategies.