Microbial communities featuring potentially pathogenic characteristics have been found living in the shower hoses at a major US hospital, as a result of new research from the US Environmental Protection Agency and the Georgia Institute of Technology.
While its long been known that the human-built environment is home to all sorts of specialized microbial communities, not much work has been done to really explore the subject, or its implications. The new work — which has been published in the journal Applied and Environmental Microbiology — scratches the surface of what’s going on on the micro-scale in areas where antibiotics are in common use, giving new, if very limited, insight.
While the Environmental Protection Agency (EPA) and Georgia Institute of Technology researchers have yet to determine if the bacterial communities in question are a health risk, the work is interesting. Here are some excerpts from a new press release:
The study documented bacteria — and related genes — using cutting-edge metagenomic techniques that allow the characterization of organisms that cannot be detected using traditional culture-based microbiology assays.
…But because some of the genes could indicate pathogenic characteristics — such as resistance to antibiotics — the researchers want to learn more about the potential health implications, and whether other buildings house similar biofilms. Antibiotic resistance is a public health emerging priority identified by the World Health Organization, which in 2015 released a global action plan to address the problem.
…The study began by culturing bacteria from 40 shower hoses removed from individual hospital rooms by EPA researchers. Nucleic acid was extracted from five of the shower hoses and processed using next-generation sequencing technology. The sequencing data was sent to Georgia Tech, where doctoral student Maria Juliana Soto-Girón matched the sequences against known bacteria — and genes that have known effects, such as virulence and antibiotic resistance.
The microbiome study found an abundant population of bacteria that the researchers believe are novel “Mycobacterium-like” species not described previously, closely related to Mycobacterium rhodesiae and Mycobacterium tusciae. Traditional culture-based methods instead identified organisms affiliated with Proteobacteria — such as members of the genera Sphingomonas, Blastomonas and Porphyrobacter — as the most abundant.
The biofilm communities harbored genes related to disinfectant tolerance, which constituted 2.3% of the total annotated proteins — and a lower abundance of virulence determinants related to colonization and evasion of the host immune system. Additionally, genes potentially conferring resistance to beta-lactam, aminoglycoside, amphenicol and quinolone antibiotics were identified. The frequency of these genes was higher than the frequency found in Lake Lanier, a natural freshwater ecosystem that has been studied by the Georgia Tech research team, suggesting that the drinking water pipe environments merit closer attention.
…Though well-known pathogens weren’t seen in abundance, the presence of genes for antibiotic resistance, resistance to water disinfectants and virulence raises concerns because bacteria can share such genes to potentially become more significant health threats.
“If they have a core of genes, they may be receptive to acquiring other genes that will render these microorganisms more problematic,” stated Jorge Santo Domingo, a microbial ecologist with the EPA’s Office of Research and Development in Cincinnati. “These organisms are very good at living in difficult environmental conditions with limited carbon sources, so fighting them could become a challenging proposition. We don’t know if they constitute a problem, but we certainly want to find out.”
Commenting on the use of the methods, he also stated: “Metagenomics gives you a more complete and quantitative picture of what microorganisms are there and how abundant they are. This shows that traditional culture methods are limited in what they can detect, and that they can often provide a biased look at what is there.”