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Published on: February 23, 2014
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Cell-associated bacteria in the human lung microbiome.
Robert P Dickson1, John R Erb-Downward1, Hallie C Prescott1
1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Microbiome
|September 11, 2014
Summary
The majority of lung bacteria are attached to cells, not free-floating in bronchoalveolar lavage (BAL) fluid. This cell-association is linked to acute lung infections and specific bacterial groups.
Area of Science:
- Microbiology
- Pulmonology
- Genomics
Background:
- Bronchoalveolar lavage (BAL) fluid harbors previously unrecognized bacterial communities.
- Host inflammatory signals can trigger bacteria to transition from biofilms to a virulent, free-living state.
- The proportion of lung microbiota that is cell-associated remains largely unknown.
Purpose of the Study:
- To investigate the localization of bacteria within bronchoalveolar lavage (BAL) fluid.
- To determine the proportion of the lung microbiota that is cell-associated versus free-living.
- To correlate bacterial localization with indicators of lung health and infection.
Main Methods:
- Collected 46 BAL specimens from lung transplant recipients.
- Divided specimens into 'whole BAL' and 'acellular BAL' aliquots.
- Analyzed aliquots using bacterial 16S rRNA gene pyrosequencing.
Main Results:
- Bacterial signal detected in 96% of whole BAL vs. 52% of acellular BAL (p≤0.0001).
- Detection in acellular BAL correlated with acute infection markers (neutrophilia, high DNA, low diversity).
- Acellular BAL had fewer species and decreased abundance of Prevotella and Pseudomonas fluorescens.
Conclusions:
- A novel method was developed to localize lung microbiota.
- Prominent lung microbiome members are cell-associated, possibly through biofilms, adhesion, or intracellularity.
- Bacterial cell association is a key factor in lung microbiome dynamics, especially during infection.
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