Microbial Evidence in Congenital Pulmonary Airway Malformations of Young Asymptomatic Infants

Experts of pediatric endosurgery recommend early thoracoscopic resection of congenital pulmonary airway malformations (CPAM) even in asymptomatic infants due to the risk of later infections. However, neither the rate of lower airway inflammation nor the underlying microbes and their pathogenic potential have been revealed in CPAMs yet. Using latest gene-sequencing techniques, we present the first study analyzing the pulmonary microbiome in young asymptomatic infants with CPAM. Seven asymptomatic infants (age 2-3 months) underwent thoracoscopic lobectomy for CPAM. Preoperatively, blood test was taken to rule out systemic infections. Surgical specimen was screened and graded for local inflammation by hematoxylin and eosin (HE) histology. The pulmonary microbiome and mycobiome were assessed using next-generation sequencing. Preoperatively, all infants had normal white blood cell counts and normal C-reactive protein (CRP) levels. Microbial evidence was found in 4/7 patients, 3 being bacteria (Pseudomonas twice, Streptococcus sp. once) and 1 fungal species (Pneumocystis jirovecii, mostly known from immunosuppressed patients, and Preussia funiculata). Histologically, both Pseudomonas and fungi were associated with low and intermediate pulmonary inflammation, whereas Streptococcus was negative for leucocyte infiltration. For the first time ever this study revealed genetic evidence of pathogenic microbes in 4/7 CPAMs causing lower airway inflammation in 3/7 asymptomatic young infants. Especially pseudomonas and fungi represent considerable pathogenic potential and call for a broader, age-dependent, multicenter study of CPAMs. Such data could be important for pediatric surgeons counseling parents about the necessity and timing of thoracoscopic resections.