It’s common knowledge that the average human body consists of more microorganisms than it does human cells, but no one ever talks about the symbiotic relationship that we’ve developed with each species that inhabits our tissues. Surely, when you think about bacteria and other microbes living on (or in!) you, your first thought is the microbes that live in your guts. But, this symbiotic relationship we’ve developed with other microbes extends much farther than your digestive tract. In fact, your human microbiome covers your entire body, from your skin to your inner digestive tract, in your mouth, on your scalp, everywhere!
Here’s a list of some of the most common human-inhabiting microbes that live amongst your tissues, day in and day out.
1. Demodex folliculorum
Demodex folliculorum is a type of parasitic mite that lives ON YOUR FACE. As we know with other species, mites love to have something on which to cling, so Demodex folliculorum will most likely be found around the hair follicles on your face. If you are thinking “but I wax my entire face!”, here’s a list of where Demodex folliculorum love to live:
- nose hair
- the tiny hair that covers your entire face, but is most commonly on your cheeks and forehead (which my mom used to lovingly call “peach fuzz”).
Demodex folliculorum also like to live in your pores. They can be found on other parts of your body, too, but the face region is the most common. Now, don’t hurry to the nearest sink to wash your face. Demodex folliculorum are mostly harmless, and is classified as commensal, which means they benefit from consuming your dead skin and sebaceous gland tissue cells. Since Demodex folliculorum infestation is relatively common, they are considered a part of your normal skin fauna.
In the last 10 years or so, dermatologists have theorized that a heavy infestation of Demodex folliculorum may be the cause of rosacea in later years in life.
2. Spirochaetes spp.
I can’t tell you how many times I’ve heard someone say “…but a dog’s mouth is supposedly really clean!” as a dog licks their face. First off, did you know that dogs consider cat feces a delicacy? Secondly, I’d love to believe that dogs have some secret antimicrobial property that allows them to cure all ailments, but let’s be realistic. We know that magical property only exists in unicorns.
Mouths are pretty disgusting places, regardless of what species you are. For humans with periodontal diseases (such as gingivitis or other oral inflammatory infections), Spirochaetes spp. are levels are elevated.
The Spirochaetes spp. belong to a bacterial phylum that have double membranes (diderm). They are most commonly long coils, and live in those hard-to-reach areas of your mouth. To reproduce, they undergo asexual transverse binary fission, producing two identical cells.
If you have good oral hygiene practices, then you should have nothing to worry about with Spirochaetes spp. They will be found in your mouth no matter what. The only time Spirochaetes spp. can become a problem is if you have periodontal diseases, which can lead to an active infection.
3. Candida albicans
Candida albicans is a common species of yeast that lives in and on your body. You depend on Candida albicans for digestion, as it exists as a part of our normal gut flora. Yet, sometimes overgrowth can occur, causing candidiasis.
Candidiasis can rear its ugly head in many anatomical locations. We most commonly hear about yeast infections affecting the female reproductive system, but yeast can inhabit your body in many different areas.
Yeasts like to live in warm moist areas, so oral tissues are another common location to see a yeast infection. Extreme cases can cause thrush on the tongue. Candidaisis can also occur in your ocular tissues (eyes), and occasionally on the skin.
I'm keeping this post short because it's my favorite day of the whole year. Halloween is a great time for scientists because we get to put our creative nature into costumes! If this post wasn't scary enough for you, feel free to check out my post from last Halloween.