Abstract

The environments we humans encounter daily are sources of exposure to diverse microbial communities, some of potential concern to human health. In this study, we used culture-independent technology to investigate the microbial composition of biofilms inside showerheads as ecological assemblages in the human indoor environment. Showers are an important interface for human interaction with microbes through inhalation of aerosols, and showerhead waters have been implicated in disease. Although opportunistic pathogens commonly are cultured from shower facilities, there is little knowledge of either their prevalence or the nature of other microorganisms that may be delivered during shower usage. To determine the composition of showerhead biofilms and waters, we analyzed rRNA gene sequences from 45 showerhead sites around the United States. We find that variable and complex, but specific, microbial assemblages occur inside showerheads. Particularly striking was the finding that sequences representative of non-tuberculous mycobacteria (NTM) and other opportunistic human pathogens are enriched to high levels in many showerhead biofilms, >100-fold above background water contents. We conclude that showerheads may present a significant potential exposure to aerosolized microbes, including documented opportunistic pathogens. The health risk associated with showerhead microbiota needs investigation in persons with compromised immune or pulmonary systems.

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Data Availability

Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. EU629353–EU635442 and EU697021–EU697072).

Acknowledgments.

We thank Dr. Marcel Behr for advice on M. avium taxonomy, Thomas Giddings for his invaluable assistance with the SEM, the students of Spring 2006 MCDB 4110 at the University of Colorado at Boulder for their initial efforts on this research, Ray Grunzinger for the collection of many showerhead swab samples, and the multiple people and institutions that allowed us access to their showerheads. This work was supported by grants from the Alfred P. Sloan Foundation and the National Institute of Occupational Safety and Health to N.R.P.

Supporting Information

Supporting Information (PDF)
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Information & Authors

Information

Published in

Go to Proceedings of the National Academy of Sciences
Go to Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences
Vol. 106 | No. 38
September 22, 2009
PubMed: 19805310

Classifications

Data Availability

Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. EU629353–EU635442 and EU697021–EU697072).

Submission history

Received: June 25, 2009
Published online: September 22, 2009
Published in issue: September 22, 2009

Keywords

  1. bioaerosols
  2. Mycobacterium avium complex
  3. Non-tuberculous mycobacteria
  4. public health
  5. rRNA metagenomics

Acknowledgments

We thank Dr. Marcel Behr for advice on M. avium taxonomy, Thomas Giddings for his invaluable assistance with the SEM, the students of Spring 2006 MCDB 4110 at the University of Colorado at Boulder for their initial efforts on this research, Ray Grunzinger for the collection of many showerhead swab samples, and the multiple people and institutions that allowed us access to their showerheads. This work was supported by grants from the Alfred P. Sloan Foundation and the National Institute of Occupational Safety and Health to N.R.P.

Notes

This article contains supporting information online at www.pnas.org/cgi/content/full/0908446106/DCSupplemental.

Authors

Affiliations

Leah M. Feazel
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347; and
Laura K. Baumgartner
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347; and
Kristen L. Peterson
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347; and
Daniel N. Frank
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347; and
J. Kirk Harris
Department of Pediatrics, University of Colorado Denver, Aurora, CO 80045
Norman R. Pace1 [email protected]
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347; and

Notes

1
To whom correspondence should be addressed. E-mail: [email protected]
Contributed by Norman R. Pace, July 29, 2009
Author contributions: L.M.F., L.K.B., and N.R.P. designed research; L.M.F., L.K.B., and K.L.P. performed research; D.N.F. and J.K.H. contributed new reagents/analytic tools; L.M.F., K.L.P., D.N.F., J.K.H., and N.R.P. analyzed data; and L.M.F. and N.R.P. wrote the paper.

Competing Interests

The authors declare no conflict of interest.

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    Opportunistic pathogens enriched in showerhead biofilms
    Proceedings of the National Academy of Sciences
    • Vol. 106
    • No. 38
    • pp. 16005-16536

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