New York City’s subway system harbours drug-resistant microbes and even DNA fragments associated with anthrax and Bubonic plague, researchers have found.
However, majority of the 637 known bacterial, viral, fungal and animal species researchers detected were non-pathogenic and represent normal bacteria present on human skin and human body.
The findings are generally reassuring, indicating no need to avoid the subway system or use protective gloves, said the study’s senior investigator, Dr Christopher E Mason, an assistant professor in Weill Cornell’s Department of Physiology.
The researchers have demonstrated that it is possible and useful to develop a “pathogen map” – dubbed a “PathoMap” – of a city, with the heavily travelled subway a proxy for New York’s population.
Culture experiments revealed that all subway sites tested possess live bacteria. Strikingly, about half of the sequences of DNA they collected could not be identified – they did not match any organism known to the US National Center for Biotechnology Information or the Centers for
Disease Control and Prevention.
These represent organisms that New Yorkers touch every day, but were uncharacterised and undiscovered until this study, researchers said.
“Our data show evidence that most bacteria in these densely populated, highly trafficked transit areas are neutral to human health, and much of it is commonly found on the skin or in the gastrointestinal tract,” Mason said.
“These bacteria may even be helpful, since they can out-compete any dangerous bacteria,” he said.
However, 12 per cent of the bacteria species researchers sampled showed some association with disease. For example, live, antibiotic-resistant bacteria were present in 27 per cent of the samples they collected.
They also detected two samples with DNA fragments of Bacillus anthracis (anthrax), and three samples with a plasmid associated with Yersinia pestis (Bubonic plague) – both at very low levels.
Notably, the presence of these DNA fragments do not indicate that they are alive, and culture experiments showed no evidence of them being alive.
“Despite finding traces of pathogenic microbes, their presence isn’t substantial enough to pose a threat to human health,” Mason said.
“The presence of these microbes and the lack of reported medical cases is truly a testament to our body’s immune system, and our innate ability to continuously adapt to our environment,” he said.
The study was published in the journal Cell Systems.