Effects of bronchoconstriction, minute ventilation, and deep inspiration on the composition of exhaled breath condensate.
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ABSTRACT:
SUBMITTER: Debley JS
PROVIDER: S-EPMC3014689 | biostudies-other | 2011 Jan
REPOSITORIES: biostudies-other
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Project description:The lung microbiota is commonly sampled using relatively invasive bronchoscopic procedures. Exhaled breath condensate (EBC) collection potentially offers a less invasive alternative for lung microbiota sampling. We compared lung microbiota samples retrieved by protected specimen brushings (PSB) and exhaled breath condensate collection. We also sought to assess whether aerosolized antibiotic treatment would influence the lung microbiota and whether this change could be detected in EBC. EBC was collected from 6 conscious sheep and then from the same anesthetized sheep during mechanical ventilation. Following the latter EBC collection, PSB samples were collected from separate sites within each sheep lung. On the subsequent day, each sheep was then treated with nebulized colistimethate sodium. Two days after nebulization, EBC and PSB samples were again collected. Bacterial DNA was quantified using 16S rRNA gene quantitative PCR. The V2-V3 region of the 16S rRNA gene was amplified by PCR and sequenced using Illumina MiSeq. Quality control and operational taxonomic unit (OTU) clustering were performed with mothur. The EBC samples contained significantly less bacterial DNA than the PSB samples. The EBC samples from anesthetized animals clustered separately by their bacterial community compositions in comparison to the PSB samples, and 37 bacterial OTUs were identified as differentially abundant between the two sample types. Despite only low concentrations of colistin being detected in bronchoalveolar lavage fluid, PSB samples were found to differ by their bacterial compositions before and after colistimethate sodium treatment. Our findings indicate that microbiota in EBC samples and PSB samples are not equivalent.IMPORTANCE Sampling of the lung microbiota usually necessitates performing bronchoscopic procedures that involve a hospital visit for human participants and the use of trained staff. The inconvenience and perceived discomfort of participating in this kind of research may deter healthy volunteers and may not be a safe option for patients with advanced lung disease. This study set out to evaluate a less invasive method for collecting lung microbiota samples by comparing samples taken via protected specimen brushings (PSB) to those taken via exhaled breath condensate (EBC) collection. We found that there was less bacterial DNA in EBC samples compared with that in PSB samples and that there were differences between the bacterial communities in the two sample types. We conclude that while EBC and PSB samples do not produce equivalent microbiota samples, the study of the EBC microbiota may still be of interest.
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Project description:RationaleRecent studies have reported acidification of exhaled breath condensate (EBC) in inflammatory lung diseases. This phenomenon, designated "acidopnea," has been attributed to airway inflammation.ObjectivesTo determine whether salivary acids and bases can influence EBC pH in chronic obstructive pulmonary disease (COPD).MethodsMeasurements were made of pH, electrolytes, and volatile bases and acids in saliva and EBC equilibrated with air in 10 healthy subjects and 10 patients.ResultsThe average EBC pH in COPD was reduced (normal, 7.24 +/- 0.24 SEM; range, 6.11-8.34; COPD, 6.67 +/- 0.18; range, 5.74-7.64; p = 0.079). EBCs were well buffered by NH(4)(+)/NH(3) and CO(2)/HCO(3)(-) in all but four patients, who had NH(4)(+) concentrations under 60 micromol/L, and acetate concentrations that approached or exceeded those of NH(4)(+). Saliva contained high concentrations of acetate (approximately 6,000 micromol/L) and NH(4)(+) (approximately 12,000 micromol/L). EBC acetate increased and EBC NH(4)(+) decreased when salivary pH was low, consistent with a salivary source for these volatile constituents. Nonvolatile acids did not play a significant role in determining pH of condensates because of extreme dilution of respiratory droplets by water vapor (approximately 1:12,000). Transfer of both acetic acid and NH(3) from the saliva to the EBC was in the gas phase rather than droplets.ConclusionsEBC acidification in COPD can be affected by the balance of volatile salivary acids and bases, suggesting that EBC pH may not be a reliable marker of airway acidification. Salivary acidification may play an important role in acidopnea.
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2017-12-06 | PXD007591 | Pride