Opportunistic pathogens enriched in showerhead biofilms

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.bioaerosols ͉ Mycobacterium avium complex ͉ Non-tuberculous mycobacteria ͉ public health ͉ rRNA metagenomics

Candidate phylum TM6 genome recovered from a hospital sink biofilm provides genomic insights into this uncultivated phylum

“…Across all gated events, 232 total 16S sequences were within the domain Bacteria. Some of the most highly detected genera such as Acinetobacter and Sphingomonas are consistent with those found in microbial communities associated with drinking water distribution systems (17,38,39). From the 32 wells with 100 low-fluorescent events in each, 6 wells produced a 16S sequence.…”

“…S7), which suggests that this phylum has a cosmopolitan distribution, although typically found at low relative abundance. Its ecological distribution (derived from published and unpublished studies that have deposited related sequences in GenBank) includes domestic water sources (17,39,45), acidic cave biofilms, acid mine drainage biofilms (46), wastewater biofilms (47), soil, contaminated groundwater and subsurface sites (48,49), aquatic moss, hypersaline mats, peat bogs, and peat swamps (30,50). These and additional environments where TM6 was detected in 16S rRNA gene clone libraries, including a number of biofilm-related samples, are highlighted in SI Appendix, Table S1.…”

“…Several studies indicate that TM6 16S sequences are commonly detected in biofilms from domestic water systems (SI Appendix, Table S1). Five such sequences were discovered along with potential opportunistic pathogens in showerhead biofilms (17). A recent study of a more than 20-y-old drinking water network that compared bacterial core communities in bulk water and associated biofilms revealed that the biofilm samples contained a unique community with no overlapping phylotypes with the bulk water samples (45).…”

“…Several pathogens including Escherichia coli, Legionella pneumophila (10-13), Vibrio cholerae (14), and Helicobacter pylori (15,16) have been detected in biofilms within water distribution systems. A recent 16S rRNA gene (abbreviated henceforth as 16S unless otherwise stated) molecular survey also revealed significant loads of Mycobacterium avium in showerhead biofilms (17). Based on these findings, indoor environments can clearly serve as significant reservoirs of pathogenic bacteria, and therefore there is great interest in investigating the rare and abundant bacterial species within biofilms in these environments.…”

Non-pathogenic Neisseria: members of an abundant, multi-habitat, diverse genus

“…Neisseria have been found in sites closely associated with humans, and are, for example, a component of the microbiota of showerhead biofilms as determined by DNA analysis (Feazel et al, 2009) and mattress dust (Ege et al, 2012). Of note, there was a significant inverse correlation between the onset of hay fever with the detection of Neisseria in mattress dust, suggesting that exposure to Neisseria might confer a degree of protection to children (Ege et al, 2012).…”