Our skin is home to a large number of bacteria, fungi, and viruses, and each of us have a unique fingerprint of our particular mix of microbial communities that is defined by its genetic makeup or microbiome. New research now shows that despite regular cleaning and contact with microbe-contaminated objects, our personal skin microbiome remains surprisingly stable over time.
Writing in the journal Cell, researchers from the National Human Genome Research Institute (NHGRI) and the National Cancer Institute (NCI) - both in Bethesda, MD - suggest their findings should help us better understand how skin diseases develop.
While most of the microbes that live on our skin are friendly and cause no harm, some have been linked to skin disorders, such as acne, eczema, and psoriasis.
Studies of the more harmful skin microbes have helped understand, for example, why eczema tends to affect moist areas such as skin in the bends of the arms and legs, while psoriasis tends to appear on the outside, more exposed parts of elbows and knees.
Researchers have found that skin microbial communities remain remarkably stable over time, despite coming into regular and frequent contact with other sources of bacteria, fungi, and viruses, including other people, clothing, surfaces, and bacteria-laden objects.
Researchers analyzed the genetic makeup of microbes in skin samples taken from 12 healthy volunteers at three successive intervals, ranging from one month to two years apart. The samples came from 17 sites on the body and the approach used for analysis was ‘metagenomic shotgun sequencing.’
In their paper, senior study authors Dr. Julie Segre, of the NHGRI, and Dr. Heidi Kong, of the NCI note how they found ‘an individual's short- and long-term community similarity significantly exceeded similarity between individuals,’ and that these findings are similar to ‘observations in gut and other communities.’
However, they also found that the stability of the microbial communities varied from person to person, and to different extents with different strains. For example, oily sites - such as on the back and in the tube that runs from the outer ear to the middle ear - showed the least variation over time, as did highly exposed and dry sites, such as the palms.
But on skin areas with a much larger range of different microbes, such as the feet and moist sites, the researchers found the microbial fingerprint was much less stable over time. They suggest this could be because of the influence of personal hygiene or because the sites are exposed to more variable environments.
There are possibilities for future studies which would include patients with eczema and skin disorders that arise because parts of the body’s immune system are missing. These studies can use the knowledge of the relative stability of the skin microbial communities in healthy adults to understand how various exposures or disease state may alter these skin microbes. For instance, researchers can study acne patients to find out if specific strains of skin microbes flourish during flare-ups or change when patients take antibiotics.