Research ArticlesLUNG PHYSIOLOGY

Quantitative Analysis of the Human Airway Microbial Ecology Reveals a Pervasive Signature for Cystic Fibrosis

Science Translational Medicine  26 Sep 2012:
Vol. 4, Issue 153, pp. 153ra130
DOI: 10.1126/scitranslmed.3004458

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There is There, There

Although the absence of evidence is not necessarily evidence of absence,* scientists have generally considered the inability to culture microbes from tissues or other medical specimens to be evidence of sterility. For example, the health of the human lung has been defined in part by whether or not microbes are present. Now, Blainey et al. use high-throughput sequencing to survey microbes in sputum from control subjects and patients with the genetic disease cystic fibrosis (CF) and show that both groups have diverse, albeit different, microbial communities.

Patients with CF suffer severe lung dysfunction and often die from respiratory failure. Mucus build-up in the lungs can cause life-threatening infections, which are treated by long courses of antibiotics. However, sometimes patients benefit clinically from this therapy even while their lungs continue to house bacteria. When the authors performed high-throughput pyrosequencing of 16S ribosomal DNA on sputum from 16 CF patients and 9 control individuals, they found that both groups of samples contained multiple microbial species. But CF patients displayed a different microbial ecology, most notably when one considered bacterial phylotypes that currently cannot be cultured in the lab. Although all patient samples did not contain an identical complement of organisms, all displayed a subset that constituted a microbial profile characteristic of CF. In fact, even when typical CF pathogens were excluded from the analysis, the microbial profiles still distinguished between control-subject and CF-patient samples. Similar findings were obtained from lung tissue taken from CF patients versus patients with other lung diseases. To bring the sequencing findings back to the clinic, the authors found that decreased microbial diversity correlated with the extent of inflammation in CF lungs.

*Often attributed to cosmologist Martin Rees.