Metagenomic Analysis of the Lung Microbiome in Chemically Injured and Healthy Individuals

Background and Aim: The role of the lung microbiome in respiratory complications associated with chemicals such as sulfur mustard or chlorine gas has yet to be determined. The aim of this study was to compare the structure and composition of the lung microbiome in chemically injured and healthy individuals in order to understand the relation between the population of the lung microbiota and respiratory complications caused by exposure to these chemicals. Methods: To study lung microbiota, the bronchial alveolar lavage (BAL) fluids were collected from 17 chemically injured and 15 healthy cases during the bronchoscopy procedure. The diversity of lung bacteria present in BAL samples was explored using 16S rRNA gene sequencing. Results: The lung microbiome dominated by members of phyla Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, Fusobacteria and Synergistetes which collectively accounted for > 95% of sequences. At the genus level, members of the genera Prevotella, Leptotrichia, Atopobium, Aggregatibacter, Catonella, and Oribacterium showed more than 2-fold increase in abundance in the lung microbiome of chemically injured patients. Comparing lung bacterial community at the species level, however, revealed an increased prevalence of members of Rothia mucilaginosa (3-fold), Prevotella melaninogenica (2.7-fold), Prevotella pallens (3.5-fold), Actinobacillus parahaemolyticus (2.5-fold), Veillonella parvula (2.5-fold), and Neisseria subflava (1.5-fold) in these patients. Conclusion: An increased abundance of bacterial species known to associate with airway inflammation suggested their implications in respiratory failure in chemically injured patients. Monitoring and maintaining the homeostasis of the microbial population colonizing lung of chemically injured patients will pave the way to develop a more targeted treatment for these patients.