The Skin Microbiome

What is the skin microbiome?

The human skin is home to a diverse microbiome, consisting of bacteria, fungi, viruses, and other microorganisms. These microorganisms can play important roles in maintaining skin health and protecting against infections.

The composition of the skin microbiome can vary depending on factors such as age, gender, ethnicity, and environmental exposures. However, certain bacterial species are commonly found on the skin of healthy individuals, such as Staphylococcus epidermidis, Propionibacterium acnes, and Corynebacterium species. Some species of Lactobacillus are known to live on the skin, although they are not as abundant as in the gut and vaginal biomes.

The skin microbiome can interact with the immune system, and a balanced and diverse microbiome is thought to help support skin health and protect against infections. For example, the skin microbiome can help to prevent the overgrowth of harmful bacteria by competing for resources and producing antimicrobial compounds.

However, imbalances in the skin microbiome can also contribute to the development of skin conditions such as acne, eczema, and psoriasis.

Maintaining good hygiene practices and avoiding overuse of antimicrobial products may help to support a healthy and balanced skin microbiome.

How does the skin microbiome influence the skin’s pH?

The skin’s pH is influenced by a number of factors, including the composition of the skin microbiome. The skin has an acidic pH, typically ranging from 4 to 6, which is important for maintaining the skin’s natural barrier function and protecting against infections.

The skin microbiome, particularly the types and abundance of bacteria present, can influence the skin’s pH by producing or consuming various metabolites. For example, some bacteria produce short-chain fatty acids (SCFAs), such as lactic acid, which can lower the pH of the skin. Lactobacillus species, which are known to live on the skin, are particularly adept at producing lactic acid, which can help to lower the skin’s pH and maintain a healthy microbiome.

On the other hand, some bacteria can produce alkaline compounds, which can raise the skin’s pH and disrupt the natural barrier function. For example, certain strains of Staphylococcus aureus, which are commonly found on the skin of individuals with atopic dermatitis (eczema), can produce urease, an enzyme that breaks down urea and raises the pH of the skin.

Overall, the composition of the skin microbiome can influence the production of various metabolites that can affect the skin’s pH. A balanced and diverse skin microbiome, with a healthy mix of beneficial and harmful bacteria, is important for maintaining a healthy skin pH and protecting against infections and inflammation.

Can the skin microbiome help with skin conditions?

Psoriasis

Research has shown that the skin microbiome of individuals with psoriasis is different from that of healthy individuals, with a decrease in the diversity of microbial species and changes in the relative abundance of certain species.

One study found that the skin microbiome of individuals with psoriasis had a lower abundance of certain beneficial bacteria, such as Staphylococcus epidermidis, which is known to play a role in maintaining the skin’s natural protective barrier. In contrast, there was a higher abundance of certain harmful bacteria, such as Staphylococcus aureus, which is known to contribute to skin infections and inflammation.

Other studies have also found differences in the abundance of certain fungal species in individuals with psoriasis, with a higher abundance of certain species such as Malassezia globosa and Malassezia restricta, which are known to contribute to skin irritation and inflammation.

Overall, the exact species that are high or low in psoriasis may vary depending on the individual and the severity of their condition. However, it is clear that changes in the skin microbiome are a contributing factor to the development and severity of psoriasis symptoms, and may be a target for future treatments.

Eczema

The skin of individuals with eczema is often colonized by a higher density and different types of bacteria, including Staphylococcus aureus. These bacteria can contribute to the development and persistence of eczema by triggering an immune response and causing skin inflammation.

The skin barrier of individuals with eczema is also compromised, which means that their skin is less able to retain moisture and protect against environmental irritants. This can lead to dryness, cracking, and flaking of the skin.

Recent research has shown that the skin microbiome plays an important role in the development and progression of eczema. A balanced and diverse skin microbiome is important for maintaining a healthy skin barrier and protecting against infections and inflammation. Alterations in the skin microbiome, such as an overgrowth of harmful bacteria or a loss of beneficial bacteria, can contribute to the development of eczema.

Treatment of eczema typically involves a combination of strategies to restore the skin barrier and reduce inflammation. This may include topical moisturizers, topical corticosteroids, and other medications to manage symptoms. In addition, strategies to restore a healthy skin microbiome, such as the use of probiotics and prebiotics, may be beneficial for some individuals with eczema.

Acne

The skin microbiome of individuals with acne has been found to be different from that of individuals without acne. Propionibacterium acnes (P. acnes) is a bacterium that is commonly associated with acne, but recent research has shown that other bacterial species may also play a role in the development and progression of acne. For example, some studies have found that individuals with acne have a higher abundance of the bacterium Cutibacterium acnes, which was previously classified as a subspecies of P. acnes, than individuals without acne.

In addition to changes in the skin microbiome, hormonal imbalances, such as an increase in androgen levels, can also contribute to the development of acne. Androgens can stimulate the sebaceous glands in the skin to produce more sebum, an oily substance that can clog pores and contribute to the formation of acne lesions.

The gut microbiome may also play a role in the development of acne, as studies have found a link between alterations in the gut microbiome and acne. For example, some studies have found that individuals with acne have lower levels of beneficial bacteria, such as Bifidobacterium, in their gut microbiome.

Does my skin care regimen impact my skin microbiome?

The use of harsh skin products can disrupt the natural balance of microorganisms that live on the skin, leading to changes in the skin’s pH and overall health. This disruption can cause a range of skin problems, including dryness, irritation, and inflammation, and can also contribute to the development of skin infections.

Many common skincare products, such as soaps, cleansers, and toners, contain harsh chemicals that can damage the skin’s protective barrier and strip away natural oils that keep the skin hydrated and healthy. This can create an environment that is more hospitable to harmful bacteria, leading to an overgrowth of these microorganisms and potentially causing skin infections.

In addition to disrupting the natural balance of microorganisms on the skin, harsh skincare products can also contribute to the development of other skin problems, such as acne, by clogging pores and trapping bacteria and other debris on the surface of the skin.

To minimize the impact of harsh skincare products on the skin, it is important to choose products that are gentle and free of harsh chemicals. This can include choosing products that are formulated specifically for sensitive skin or that contain natural ingredients like plant oils and extracts.