It's mostly skin bugs lurking on the Boston T, according to a study from Harvard T.H. Chan School of Public Health researchers.
Curtis Huttenhower and his colleagues collected 73 samples from train cars and stations in the Boston transit system. Samples from train cars were taken from poles, seats, and grips, while station samples were obtained from the screens and sides of ticket machines. They then used 16S amplicon and shotgun metagenomic sequencing to profile these microbial communities. As they reported this week in mSystems, commensal human skin bacteria dominated these surfaces.
"From what we found, the bugs you encounter riding the T is not any worse than what you would expect from shaking someone's hand," Huttenhower tells the Los Angeles Times. "Sure, a lot of microbes are involved, but it's nothing to worry about."
The researchers also uncovered some microbes that generally live in the human mouth — mostly at "about sneeze and cough level" the LA Times notes.
Huttenhower tells the paper that they didn't specially look for pathogens, but did check for some obvious ones. They also avoided sampling the subway system during flu season or the summer so as to get a baseline microbiome.
Previous studies examining air samples from the New York City and Hong Kong subway systems also detected human skin microbes as well as some soil- and water-dwelling ones. A metagenomic analysis of the New York system also recently found skin-related genera, but also hints of pathogens, though its report of finding sequencing reads similar to those from Bacillus anthracis and Yersinia pestis was criticized, and the authors issued an erratum that toned down their interpretation of their Blast results.
Huttenhower tells the LA Times that his lab next plans to determine whether any microbes were alive when they were sampled and, if so, how they survive on the subway.