Smoking Affects Lung Microbiota, ARDS Risk in Trauma Patients

Data from a recent pilot study published in the American Journal of Respiratory and Critical Care Medicine suggest that smoking-related changes in lung microbiota may increase the risk for acute respiratory distress syndrome (ARDS) in patients after severe trauma.

Ariane R. Panzer, BA, from the University of California, San Francisco, and colleagues examined the lung microbiota of mechanically ventilated patients admitted to the intensive care unit (ICU) after severe blunt trauma. They used 16S rRNA gene amplicon sequencing of endotracheal aspirate samples obtained on ICU admission and at 48 hours postadmission, and quantified cigarette smoking using plasma cotinine.

Smoking status was significantly associated with lung bacterial community composition at ICU admission in 74 patients (P =.007), as well as at 48 hours postadmission in 30 patients (P =.03). Twenty-five patients were studied at both points. Plasma cotinine levels indicated that 21 patients were nonsmokers, 15 were passive smokers, and 38 were smokers. Among smokers, there was significant enrichment of potential pathogens, including streptococcus, fusobacterium, prevotella, haemophilus, and treponema.

The investigators also found enrichment of a small number of these taxa in patients who abused alcohol and were younger, suggesting these factors also may affect airway microbiota. Lung community composition at 48 hours correlated with the development of ARDS (P =.04) and was characterized by relative enrichment of enterobacteriaceae and of specific taxa already enriched at baseline in smokers, including prevotella and fusobacterium.

This pilot study is limited by a number of factors, including its small sample size, which restricts analyses adjusted for potential confounders, such as alcohol abuse and/or age, which may contribute to some of the observed differences between smokers and nonsmokers.

The authors argued that these data suggest smoke exposure selects for specific bacterial taxa in the lung biota, which remain enriched in smokers over time. The data also showed a marked divergence in bacterial community composition between 0 and 48 hours of ICU admission in trauma patients. The authors concluded that further investigations with larger sample sizes will be needed to confirm these findings and provide more detailed evaluation on the role of the lung microbiota in ARDS pathogenesis.

Reference

Panzer AR, Lynch SV, Langelier C, et al. Lung microbiota is related to smoking status and to development of ARDS in critically ill trauma patients [published online October 16, 2017]. Am J Respir Crit Care Med. doi:10.1164/rccm.201702-0441OC