A refreshing approach to the bacterial exposure issue

Readers may recall the media uproar over a scientist’s finding of elevated levels of bacteria on the structures of a kids’ playroom associated with a well-known brand of fast food restaurant. GallonDaily’s editor was sceptical, not about the findings but over the interpretation that children were at high risk of sickness caused by the bacteria. Now the results of research undertaken in the New York city subway that found much more elevated levels of many more types of bacteria, some previously unknown to science, are being reported in what GallonDaily considers to be a much more responsible fashion.

The research article, with the unhelpful (to ordinary people) title of Geospatial Resolution of Human and Bacterial Diversity with City-Scale Metagenomics, is the first article published as part of a new Elsevier journal Cell Systems. The researchers, a huge team led by Weill Cornell Medical College professor Christopher Mason, took swab samples at every station in the New York City subway system and in some other locations around the City. Among the findings:

  • identified organisms spanned 1,688 bacterial, viral, archaeal (a type of single-celled microorganisms), and eukaryotic (a broad category of microorganism) taxa (species).
  • nearly half of the DNA (48%) identified does not match any known organism.
  • predicted ancestry of human DNA left on subway surfaces can recapitulate U.S. Census demographic data, and bacterial signatures can reveal a station’s history, such as marine-associated bacteria in a hurricane-flooded station.
  • some evidence of pathogens, eg the bacterium that causes anthrax, was found. but a lack of reported cases in NYC suggests that the pathogens represent a normal, urban microbiome.
  • densely populated, highly trafficked areas of human transit show strong evidence of bacteria that are resistant to antibiotics and some presence of potentially pathogenic organisms.

The authors state that their baseline metagenomic map of NYC could help long-term disease surveillance, bioterrorism threat mitigation, and health management in the built environment of cities.

GallonDaily particularly applauds the author’s conclusion that the potentially infectious agents found in the subway and elsewhere in the City are not creating widespread sickness or disease. Instead, they likely represent normal co-habitants of a shared urban infrastructure, and they may even be essential to maintaining such an environment and likely represent a normal “healthy” metagenome profile of a city. They conclude: “Indeed, these data indicate that the subway, in general, is primarily a safe surface. Although evidence of B. anthracis, Y. pestis, MRSA, and other CDC infectious agents was found on the subway system in multiple stations, the results do not suggest that the plague or anthrax is prevalent, nor do they suggest that NYC residents are at risk.”

Maybe other researchers who go around testing public surfaces for evidence of infectious agents will take notice of this perspective and, more important though less likely, perhaps society can begin to wean itself off its current infatuation with antibacterial cleaning agents, at least some of which are causing more environmental harm and more evolution of antibiotic resistant bacteria that may in future cause a much greater problem that the bacteria presently ubiquitous in urban environments.

The full article can be found at http://www.cell.com/pb/assets/raw/journals/research/cell-systems/do-not-delete/CELS1_FINAL.pdf




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