Sorry, clean freaks. No matter how well you scrub your home, it's covered in bacteria from your own body. And if you pack up and move, new research shows, you'll rapidly transfer your unique microbial fingerprint to the doorknobs, countertops and floors in your new house, too.
In fact, researchers who studied seven families in Illinois, Washington and California could easily match up who lived where using their microscopic roommates.
Thursday's study is part of an effort to understand how the trillions of mostly beneficial bacteria that live in and on our bodies - what's called the human microbiome - interact with bugs in the environment to affect our health.
''We have so little information about where the microbes come from that shape our microbiome, whether it's for health or disease,'' said microbiologist Jack Gilbert of the Argonne National Laboratory and University of Chicago.
Where do people spend most of their time? ''It's the indoor environment. The best place to look at that was the home,'' said Gilbert, who led the Home Microbiome Project and included his own family.
Right at birth, babies start picking up microbes on the skin, in the nose, in the gut that eventually make up living communities that will share their bodies throughout life. Many of these bugs play critical roles in digestion, the immune system and other health-inducing factors. Others may make it easier to gain weight, or influence disease. What shapes the balance of good bugs and bad is a huge scientific question.
Hospital studies make clear that someone who already is sick can catch a new infection from pathogenic bacteria left behind by a previous patient.
In contrast, the new study examines healthy people, and it marks an important step: Beginning to show what's normal in a regular home, said Dr. Lisa Helbling Chadwick of the National Institutes of Health. That's a key question before scientists can explore how to possibly create healthier homes.
''You have to think about the microbiome of your home as part of your home's immune system,'' said Chadwick, of NIH's National Institute of Environmental Health Sciences, who wasn't involved with Gilbert's project. ''Instead of relying on killing bugs to stop the spread of infection, maybe we need to cultivate better bugs.''
For the study, Gilbert recruited seven households that included 15 adults, three children, three dogs and a cat. For six weeks, participants collected samples of the