Altered community compositions of Proteobacteria in adults with bronchiectasis

BACKGROUND: Bronchiectasis is a debilitating disease with chronic airway infection. Proteobacteria, the dominant phylum, can be detected with high-throughput sequencing. OBJECTIVE: To stratify Proteobacteria compositions according to culture findings in bronchiectasis. PATIENTS AND METHODS: We sampled sputum, split for culture and 16srRNA sequencing, from 106 patients with stable bronchiectasis and 17 healthy subjects. Paired sputa from 22 bronchiectasis patients were collected during exacerbations and convalescence. RESULTS: Forty-five, 41, and 20 patients with clinically stable bronchiectasis had isolated Pseudomonas aeruginosa (PA), other potentially pathogenic microorganisms, and commensals at the initial visit, respectively. The PA group (but not other groups) demonstrated significantly greater relative abundance of Proteobacteria, and lower Shannon–Wiener Diversity Index, Simpson Diversity Index, and richness compared with healthy subjects. Pseudomonas was the dominant genus that discriminated bronchiectasis patients (particularly in the PA group) from healthy subjects. Compared with baseline levels, Proteobacteria community compositions in the PA group, but not in other groups, were more resilient during exacerbations and convalescence. CONCLUSION: Proteobacteria community compositions could be partially reflected by conventional sputum bacterial culture. Significantly altered Proteobacteria community compositions – particularly, the increased relative abundance of Pseudomonas and diminished community diversity – represent critical targets for novel interventions to restore normal airway microen-vironment in patients with bronchiectasis.