The microbiome on my hand

After more than a year, I finally got back the results from the swab I sent to American Gut, a non-profit research group that studies people’s microbiomes—mostly the gut stuff. I’d swabbed my hand and sent the sample because I’d had an open wound on my finger that kept getting bigger instead of smaller—a situation that lasted about two months before it finally healed. Flesh eating bacteria, I was sure!

Anyhow, the results were not helpful, mostly because they didn’t identify the bacteria down to the species level. If you remember your biology, animal taxonomy goes in the following order: kingdom, phylum, class, order, family, genus, species. The lab results drilled down only as far as genera (the plural word for genus). I was astonished, though, that I had a list of over 170 different bacteria genera living on my hand—this would amount to thousands of different species. The genus staphylococcus was the tenth most abundant of my genera and was doubtless the cause of my problem. (As I said in an earlier blog staphylococcus epidermis is a common skin bacteria that normally causes no problems, but occasionally goes rogue and causes infection.)

Even though the results weren’t helpful, I did a little research on the skin microbiome and found some factoids based on studies of thousands of samples:

•  Your hand microbiome is in a state of constant flux and is affected by your age, handedness and gender, as well as by the products you use, your co-inhabitants and pets.
•  Women have a more diverse bacterial population than men; also, the bacterial composition of female hands is significantly more like their mobile phones than that of men.
• The bacterial composition on the hands of healthy people is different from those who are immune-compromised; oral antibiotics impact the hand microbiome.
•  As a rule, hand washing doesn’t change the microbial diversity on your hands.
•  Pet ownership increases the overall diversity of bacteria on your hands. Your hand microbiome is more like your own pet’s paws than that of a pet in another household.
• A home becomes colonized with its occupant’s microbiome, such that light switches, for example, harbor the same bacteria as your hands. Thus, objects can be identifiable to their owner—an alternative to human DNA in forensic analyses.

Get used to it. Your hands are loaded with thousands of bacteria and they leave tell-tale traces for forensic experts!

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