Possible role of anaerobes in the pathogenesis of nontuberculous mycobacterial infection

Background and objective Recent advances in cultivation-independent molecular biological modalities for detecting bacterial species have indicated that several bacterial species may play a role in the pathogenesis of certain infectious diseases. The aim of this study was to evaluate the role of bacterial flora in the pathogenesis of nontuberculous mycobacteriosis (NTM) using a bacterial floral analysis of bronchoalveolar lavage fluid (BALF) with 16S rRNA gene sequencing in patients with bronchiectasis. Methods Fifty-eight patients with bronchiectasis evaluated using chest computed tomography were enrolled. BALF obtained from the most affected lung lesions was evaluated using culture and culture-independent methodologies. Approximately 600 bp of the bacterial 16S rRNA gene (E341F-E907R) was amplified via polymerase chain reaction using universal primers, and clone libraries were constructed. Nucleotide sequences of 96 randomly chosen clones for each specimen were determined, and the homology was searched using a basic local alignment search tool to determine the bacterial phylotypes and their proportions (bacterial floral analysis) in each specimen. Results Twenty-nine patients with bronchiectasis were diagnosed with NTM based on culture-based methods using Ogawa medium. The molecular method showed a significantly high rate of anaerobes among the patients with NTM compared with that observed in the bronchiectasis patients without NTM. In addition, findings of collapse/consolidation were significantly related to the proportion of Prevotella species in the BALF samples determined using the molecular method (P-<-0.001). Conclusion Given the results of the present study, anaerobes may play an important role in the pathogenesis of bronchiectasis in patients with NTM. We compared the lung microbiome in bronchiectasis patients with and without pulmonary NTM using a molecular method with bronchoscopic specimens. Consequently, findings of collapse/consolidation on chest CT were significantly related to the proportion of Prevotella species. Anaerobes may play an important role in the pathogenesis of pulmonary NTM.