Researchers looked at how people colonize their own homes with scores of bacteria.
The research team gained insight into the complicated interaction between humans and the microbes that live on and around them, DOE/Argonne National Laboratory reported. The findings add to evidence that these communities influence human health and disease transmission.
"We know that certain bacteria can make it easier for mice to put on weight, for example, and that others influence brain development in young mice," said Argonne microbiologist Jack Gilbert, who led the study. "We want to know where these bacteria come from, and as people spend more and more time indoors, we wanted to map out the microbes that live in our homes and the likelihood that they will settle on us.
The Home Microbiome Project followed seven families including 18 people , three dogs, and one cat. The participants swabbed their hands, feet, and noses daily to get samples of the microbial populations living on them; they also took swabs from places in the house such as light switches and countertops. The researchers then performed a DNA analysis on the colonies to see what species are microbes were present in each swab.
"We wanted to know how much people affected the microbial community on a house's surfaces and on each other," Gilbert said.
The team found humans had a significant effect on the microbial communities of the house; when three of the families moved it took less than a day for the new house to have the same microbial population as the last one. People who had the most contact with each other, such as couples or parents and small children, shared the most microbes.
At one point the researchers detected a potentially pathogenic microbe called Enterobacter that was passed from one person's hand, to a counter, to another person's hand.
"This doesn't mean that the countertop was definitely the mode of transmission between the two humans, but it's certainly a smoking gun," Gilbert said. "It's also quite possible that we are routinely exposed to harmful bacteria-living on us and in our environment-but it only causes disease when our immune systems are otherwise disrupted."
These types of microbiome studies could also be used for forensic purposes.
"You could theoretically predict whether a person has lived in this location, and how recently, with very good accuracy," Gilbert said.
The paper was published today in Science.
