What Is the Skin Microbiome?

The skin microbiome is the community of bacteria, fungi, viruses, and other microorganisms that inhabit the skin surface and follicular structures. A healthy microbiome is characterised by diversity and balance, with commensal organisms helping to:

Maintain skin pH (typically 4.5–5.5 on the surface)

Compete with pathogenic organisms, preventing overgrowth

Modulate immune responses and reduce inflammation

Strengthen the skin barrier through metabolite production

Disruptions to this ecosystem called dysbiosis are increasingly linked to inflammatory skin conditions. Common triggers include aggressive cleansing, antibiotic use, hormonal shifts, diet, and environmental factors.

The Microbiome in Acne: What the Science Says

The traditional view attributed acne almost exclusively to Cutibacterium acnes overgrowth. Current evidence presents a more nuanced picture:

It is not the absolute quantity of C. acnes that matters, but which strains are dominant

Acne-prone skin shows reduced microbial diversity, with pro-inflammatory strains predominating

Staphylococcus epidermidis, a commensal organism, produces substances that suppress C. acnes virulence

Disrupting the microbiome with harsh cleansers or over-exfoliation worsens long-term acne outcomes

This understanding is shifting treatment paradigms toward approaches that restore microbiome balance rather than simply eliminating bacteria.

The Microbiome in Rosacea

Rosacea pathogenesis involves both microbiome and immune system interactions:

Demodex mite density is increased in rosacea-affected skin; their bacterial passengers (Bacillus oleronius) trigger inflammatory responses

Rosacea patients show altered skin microbiome composition compared to healthy controls

Barrier dysfunction in rosacea increases skin permeability, allowing microbial components to trigger further immune activation

Treatments that target the microbiome imbalance rather than just surface inflammation offer the potential for more durable remissions.

How Modern Treatments Affect the Microbiome

⚠️ Topical antibiotics:

Effective short-term but reduce microbial diversity and select for resistant strains. Long-term use is discouraged.

⚠️ Benzoyl peroxide:

Non-selective antimicrobial activity disrupts both pathogenic and commensal organisms.

⚠️ Aggressive exfoliation:

Disrupts the acid mantle, raising pH and creating conditions favourable to pathogenic overgrowth.

✅ Targeted, microbiome-aware formulations:

Multi-active formulas that address acne triggers without broad-spectrum disruption of commensal flora.

Microbiome-Friendly Clinical Protocols with md:ceuticals

a) Barrier First

Restoring and protecting the skin barrier is the first step in any microbiome-aware protocol. Products that support barrier function ceramides, Panthenol, Niacinamide create the conditions for healthy microbiome re-establishment.

b) pH Management

Maintaining the skin's acid mantle (pH 4.5–5.5) is essential for microbiome balance. Gentle, pH-appropriate cleansers and treatment formulations are preferred over alkaline products.

c) Targeted Anti-Inflammatory Approach

md:complex SkinClear target the four factors of acne pathogenesis sebum dysregulation, follicular hyperkeratinisation, C. acnes activity, and inflammation without broad-spectrum antimicrobial disruption.

d) Professional Treatments

Mandelic acid peels and targeted mesotherapy protocols can modulate inflammatory activity and improve skin barrier function, supporting microbiome rebalancing over a treatment series.