Lovebug: Why You Need to Embrace Your Skin Microbiome

Did you know that there is a whole universe of life existing on you? Approximately 10 million bacteria per centimeter of your skin.

I know, right?

To some people the thought is strange or even horrifying, but it is actually so normal. We have known for a long time about the importance of the gut microbiome, but more and more we’re beginning to understand what a weird and wonderful relationship we have with the bugs on our skin. Are they villains or heroes, or a little bit of both?

Let’s find out.

The basics

Our skin is famously our largest organ - we have approximately two square meters of the stuff. And it is home to millions of little creatures - bacteria, fungi, and viruses - who have colonised the area and made themselves comfortable in our skin. They are collectively called our microbiome, and they are thought to play a crucially important role our skin.

Different sites of skin on our body have different populations of organisms, and genetic sequencing has been extremely helpful in characterising these populations. Some areas of our skin are more prone to being oily (faces, chest, and back), some to being moist (the creases off our elbows and knees), and some are more dry (or forearms).

A recent review showed that oily areas of our skin were more favoured by lipophilic (lipid-loving) bacteria like Propionibacterium, while moist areas were preferred by species like Staphylococcus. There was a greater diversity of fungi found on the feet, but overall fungi are the least abundant microorganism on our skin. Viral colonisation seems to differ and be very specific person-to-person. The populations appear to be quite stable in general and don’t massively change over time with provocation. Our skin is not actually the most welcoming of environments, as it doesn’t naturally provide a lot of nutrients for these microorganisms. They have had to adapt and use what is naturally present in the very top layer of our skin (the stratum corneum), or in our sebum and sweat.

So what have they ever done for me?

It might surprise you to hear that your skin microbiome does a lot for you. It is a unique population that has quite literally grown up with you, adapting to your specific skin environment. It interacts with your own cells and helps to protect you, promoting defensive and immune responses in your skin. It also prevents nasty, pathogenic organisms from colonising and infecting your skin by outcompeting it. It helps to encourage the important barrier function of your skin.

There is also some evidence that the presence of these microorganisms on our skin is vital in teaching our immune system how to function right after we are born. To put it simply, the presence of these bugs help to teach the immune system how it should respond to future exposures of different, more dangerous microorganisms. This is still a new and fascinating area of exploration and discovery.

But can they turn on me?

They can and they do. We know that a lot of time when we get skin infections secondary to cuts or trauma to the skin, the usual culprits are bacteria that are already living on our skin. There has been some research in patients suffering with atopic dermatitis, also known as eczema. They often have Staphylococcus species cultured from the skin, and there is a hypothesis that the composition of their skin microbiome influences the progression of the disease.

Staphylococcus aureus is notorious as being a major cause of skin and surgical site infections, as well as developing resistance to antibiotics, even though it asymptomatically colonises the nares of 30% of people. Much research is focused on the interaction between toxins produced by Staphylococcus aureus and our immune system. It is still unclear, however, whether the prevalence of this particular bug in the skin microbiome is a cause of disease processes, or a side effect of the disease. We also have microorganisms like the infamous Cutibacterium acnes, which does exist on perfectly healthy skin, but which also has a major role to play in the development of acne.

Biofilms

What is a biofilm? Although well-known in many aspects of medicine, they only recently became a focus in cosmetic medicine. In injectable treatments there exists the potential formation of biofilms. The Biofilm Theory states that bacteria and filler can react to form matrix-enclosed aggregates (think of a it as a sticky layer), which then triggers a foreign body reaction.

Recently, there has been a focus on the role biofilms play in adverse reactions related to dermal fillers, including nodules, abscesses, sinuses, and delayed hypersensitivity reactions. The most common presentation for patients is that of a small, tender nodule that is culture negative. These can last for months. Originally thought to be allergic or immune responses and managed with steroids, they have shown good resolution with the use of antibiotics.

So what can you do?

Biofilms are best prevented with good aseptic technique as well as patient education, so that you know what signs and symptoms to inform your medical practitioner about.

What this means for you

The general consensus now is shifting towards the skin microbiome being a vital component of healthy skin. However, there is still a lot of work to be done to determine exactly what species and what proportions of different microorganisms are good for the skin. One phrase that I have seen a lot is “dysbiosis,” but it is a very vague and non-specific term. There is a suggestion that an imbalance in the microbiome is causing disease, however no one can say yet what the correct “balance” looks like, or has proven a strict causal relationships.

So…I should go buy some prebiotics and probiotics?

I wouldn’t rush out yet, and I’ll explain why.

This is one of those areas where we have seen some very interesting correlations and promising early research, but that doesn’t mean we should jump ahead and spend a lot of money on the hottest new skincare trend yet.

There is still a lot we don’t know. Although it seems clear that a good relationship with a diverse skin microbiome will promote skin health, we have not determined the exact details of which microorganisms do this, and in which contexts. Everyone’s microbiome is unique to them, so not all probiotics will work for all people, or they may respond very differently.

Probiotics probably won’t hurt your skin, but I would definitely discuss it with a your dermatologist first if you’re interested, so they can steer you in the right direction.

However, you should still embrace the fact that you have unique and fascinating universe living on your skin, and look forward to the day when we know even more about it. It is possible that this will lead to new treatments for skin diseases as our understanding improves, as well as overall promotion of skin health.