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Alterations in airway microbiota in patients with PaO2/FiO2 ratio ≤ 300 after burn and inhalation injury
Citation:
Walsh, D., S. McCullough, S. Yourstone, S. Jones, B. Cairns, M.D., C. Jones, I. Jaspers, AND D. Diaz-Sanchez. Alterations in airway microbiota in patients with PaO2/FiO2 ratio ≤ 300 after burn and inhalation injury. PLOS ONE . Public Library of Science, San Francisco, CA, 12(3):e0173848, (2017).
Impact/Purpose:
Exposure to wildfire smoke is a serious health risk which can disproportionally impact sensitive groups. A number of studies have shown an association between smoke exposure and worsening of respiratory symptoms, increased rates of cardiorespiratory emergency visits, hospitalizations, and even death. Identifying communities vulnerable to adverse health outcomes during smoke days can provide valuable information for local, state, and federal governments and nongovernmental organizations to prioritize public health actions and improve public health outcomes on fire-smoke days.
Description:
BACKGROUND: Injury to the airways after smoke inhalation is a major mortality risk factor in victims of burn injuries, resulting in a 15-45% increase in patient deaths. Damage to the airways by smoke may induce acute respiratory distress syndrome (ARDS), which is partly characterized by hypoxemia in the airways. While ARDS has been associated with bacterial infection, the impact of hypoxemia on airway microbiota is unknown. Our objective was to identify differences in microbiota within the airways of burn patients who develop hypoxemia early after inhalation injury and those that do not using next-generation sequencing of bacterial 16S rRNA genes. RESULTS: DNA was extracted from therapeutic bronchial washings of 48 patients performed within 72 hours of hospitalization for burn and inhalation injury at the North Carolina Jaycee Burn Center. DNA was prepared for sequencing using a novel molecule tagging method and sequenced on the lllumina MiSeq platform. Bacterial species were identified using the MTToolbox pipeline. Patients with hypoxemia, as indicated by a Pa02/FiO2 ratio ≤ 300, had a 30% increase in abundance of Streptococcaceae and Enterobacteriaceae and 84% increase in Staphylococcaceae as compared to patients with a Pa02/Fi02 ratio > 300. Wilcoxon rank-sum test identified significant enrichment in abundance of OTUs identified as Prevotella melaninogenica (p = 0.042), Corynebacterium (p=0.037) and Mogibacterium (p=0.048). Linear discriminant effect size analysis (LefSe) confirmed significant enrichment of Prevotella melaninognica among patients with a Pa02/Fi02 ratio ≤300 (p<0.05). These results could not be explained by differences in antibiotic treatment. CONCLUSIONS: The airway microbiota following burn and inhalation injury is altered in patients with a Pa02/Fi02 ratio ≤300 early after injury. Enrichment of specific taxa in patients with a Pa02/Fi02 ratio ≤300 may indicate airway environment and patient changes that favor these microbes. Longitudinal studies are necessary to identify stably colonizing taxa that play roles in hypoxemia and ARDS pathogenesis.
