Beware! Married couple share most bacteria

Know where do bacteria reign? In the cosiness of your home - at doorknobs, light switches, floors, countertops - and within relationships.

If you are married and have kids, you tend to share most of the microbial community, says a fascinating research.

And if you have pets, it changes the bacterial makeup with more plant and soil bacteria entering the house.

"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," said microbiologist Jack Gilbert from US Department of Energy's Argonne National Laboratory.

As part of the Home Microbiome Project, researchers followed seven families, which included 18 people, three dogs and one cat, over the course of six weeks.

The participants swabbed their hands, feet and noses daily to collect a sample of the microbial populations living in and on them.

They also sampled surfaces in the house, including doorknobs, light switches, floors and countertops.

"We found that people substantially affected the microbial communities in a house - when three of the families moved, it took less than a day for the new house to look just like the old one, microbially speaking," Gilbert explained.

In one home where two of the three occupants were in a relationship with one another, the couple shared many more microbes.

Married couples and their young children also shared most of their microbial community.

Within a household, hands were the most likely to have similar microbes while noses showed more individual variation.

The research also suggests that when a person (and their microbes) leaves a house, the microbial community shifts noticeably in a matter of days.

"It is quite possible that we are routinely exposed to harmful bacteria but it only causes disease when our immune systems are otherwise disrupted," Gilbert emphasised.

The paper, that also included researchers from University of Chicago, appeared in the journal Science.