Ecological Analyses of Mycobacteria in Showerhead Biofilms and Their Relevance to Human Health

15 páginas.- 5 figuras.- 70 referencias.- Supplemental material for this article may be found at https://doi.org/10.1128/mBio.01614-18

Bacteria within the genus Mycobacterium can be abundant in showerheads, and the inhalation of aerosolized mycobacteria while showering has been implicated as a mode of transmission in nontuberculous mycobacterial (NTM) lung infections. Despite their importance, the diversity, distributions, and environmental predictors of showerhead-associated mycobacteria remain largely unresolved. To address these knowledge gaps, we worked with citizen scientists to collect showerhead biofilm samples and associated water chemistry data from 656 households located across the United States and Europe. Our cultivation-independent analyses revealed that the genus Mycobacterium was consistently the most abundant genus of bacteria detected in residential showerheads, and yet mycobacterial diversity and abundances were highly variable. Mycobacteria were far more abundant, on average, in showerheads receiving municipal water than in those receiving well water and in U.S. households than in European households, patterns that are likely driven by differences in the use of chlorine disinfectants. Moreover, we found that water source, water chemistry, and household location also influenced the prevalence of specific mycobacterial lineages detected in showerheads. We identified geographic regions within the United States where showerheads have particularly high abundances of potentially pathogenic lineages of mycobacteria, and these “hot spots” generally overlapped those regions where NTM lung disease is most prevalent. Together, these results emphasize the public health relevance of mycobacteria in showerhead biofilms. They further demonstrate that mycobacterial distributions in showerhead biofilms are often predictable from household location and water chemistry, knowledge that advances our understanding of NTM transmission dynamics and the development of strategies to reduce exposures to these emerging pathogens.

Funding for this project was provided by the Innovative Research Program of the Cooperative Institute for Research in Environmental Sciences (N.F.), the High PlainsIntermountain Center for Agricultural Health & Safety (N.F.), the U.S. Department of Defense (N.F. and R.R.D.), and the Shoot for the Cure and Padosi Foundations (J.R.H.).M.D.-B. acknowledges support from the Marie Sklodowska-Curie Actions of the Horizon2020 Framework Program H2020-MSCA-IF-2016 under REA grant agreement no. 70205

Peer reviewed