D105-12 Prevalence and Age-related Acquisition of Airway Pathogens in Pediatric Primary Ciliary Dyskinesia

Abstract Rationale Chronic airway infection is a major contributor to morbidity in primary ciliary dyskinesia (PCD), yet age-specific patterns of pathogen acquisition and persistence remain poorly defined. In cystic fibrosis (CF), airway colonization follows a well-described trajectory, from early acquisition of Staphylococcus aureus (MSSA) and Haemophilus influenzae (H. flu) in infancy to predominance of Pseudomonas aeruginosa (P. aeruginosa) and other Gram-negative organisms with age. Whether similar age-dependent microbial trends occur in PCD remains unclear. Methods We conducted a retrospective cohort study of children (0-18 years) with confirmed PCD followed between 2010 and 2024. Diagnoses were established according to American Thoracic Society and European Respiratory Society criteria. Routine airway cultures were obtained two to four times annually during standardized visits and classified using the Cystic Fibrosis Leeds criteria (1) as negative, intermittent, or chronic. Age-specific prevalence of major bacterial pathogens, cumulative acquisition of first positive cultures, and time from first isolation to chronic infection are presented. Results A total of 133 patients (53 % male) were included, with a median age at first visit of 6.2 years (IQR 0.8-11.4) and median follow-up duration of 5.9 years (IQR 2.8-10.6). Across 2,597 sputum cultures, H. flu and MSSA were most frequent in infants and preschool children (6 years), each isolated in 40 % of patients, while P. aeruginosa prevalence increased with age, identified in ≈15 % of school-age children (6-11 years) and ≈20 % of adolescents (≥12 years; Figure 1A). S. pneumoniae and M. catarrhalis predominated in younger age groups, whereas S. maltophilia, Achromobacter, and MRSA were less common. Cumulative acquisition curves (Figure 1B) showed that 80 % of patients had cultured H. flu by age 18, compared with 45 % for P. aeruginosa and 10 % for MRSA. Median time from first positive culture to chronic infection was shortest for P. aeruginosa (138 days, IQR 105-344), followed by MRSA (208 days, IQR 127-637), MSSA (305 days, IQR 198-981), and H. flu (335 days, IQR 180-997). Conclusions This large single-center longitudinal study demonstrates distinct, age-dependent trends in airway pathogen prevalence in pediatric PCD. H. flu and MSSA dominate from early childhood, whereas P. aeruginosa emerges early and remains a significant pathogen throughout childhood and more readily establishes chronic infection. Regular microbiologic monitoring across childhood may enable earlier intervention and guide age-specific infection-prevention strategies in PCD. Reference: Lee TW et al. J Cyst Fibros. 2003; 2(1):29-34. doi: 10.1016/S1569-1993(02)00141-8 This abstract is funded by: None