Skin Infections

The Skin's Own Bacteria Fight Off Infection Before It Starts

There's a genuinely strong, causally tested finding here, published in one of the most rigorous general science journals.

Many common skin infections, from impetigo to more serious abscesses and cellulitis, trace back to Staphylococcus aureus, a bacterium that lives harmlessly in the nose and on the skin of roughly three in ten people without causing any problems.

Whether it stays harmless or goes on to cause an infection appears to depend partly on which other bacteria are already there.

One nasal bacterium makes its own antibiotic against the other

Researchers discovered that Staphylococcus lugdunensis, a different bacterium naturally found in some people's noses, produces a previously unknown antibiotic called lugdunin.

Lugdunin actively kills Staphylococcus aureus, and people who carried S. lugdunensis in their nose were found to be roughly 5 times less likely to also carry S. aureus, in a cohort of hospitalised patients.

A later study repeated this in 270 healthy volunteers, unconnected to any hospital, and found a near-identical result: carriers of S. lugdunensis were about 5 times less likely to carry S. aureus too.

Source: Human commensals producing a novel antibiotic impair pathogen colonization

Source: The Staphylococcus aureus-antagonizing human nasal commensal Staphylococcus lugdunensis depends on siderophore piracy

This isn't a lone example, several skin bacteria compete this way

Other common skin bacteria have since been found doing something similar. Staphylococcus hominis and Staphylococcus epidermidis, both common, harmless residents of healthy skin, produce their own antimicrobial compounds that suppress Staphylococcus aureus growth.

Beyond direct antibiotic production, some of these bacteria also interfere with the way Staphylococcus aureus communicates with itself to coordinate an infection, a process called quorum sensing, blunting its ability to organise an attack in the first place.

Together, this points to a genuinely protective principle. A diverse, well-established skin bacterial community doesn't just sit passively alongside harmful bacteria, several of its members appear to be actively working to keep them in check.

Source: Harnessing diversity and antagonism within the pig skin microbiota to identify novel mediators of colonization resistance to methicillin-resistant Staphylococcus aureus

Lugdunin does more than kill on contact, it recruits backup

Follow-up research found lugdunin doesn't just act as a simple antibiotic. It also triggers skin cells to produce more of their own natural antimicrobial compound, called LL-37, and recruits extra immune cells to the area.

This means the bacterium producing lugdunin is doing two jobs at once: directly attacking Staphylococcus aureus, and amplifying the skin's own built-in defences against it.

That combination, a direct antibiotic plus a boosted immune response, may explain why the protective effect has shown up so consistently across different studies and patient groups.

Source: Lugdunin amplifies innate immune responses in the skin in synergy with host- and microbiota-derived factors

What this means for you

A skin infection with spreading redness, warmth, swelling, fever, or pus needs a doctor's assessment, since some cases need antibiotics and a few can become serious quickly. In addition, the research above shows specific, naturally occurring skin bacteria can produce their own antibiotics against Staphylococcus aureus, cutting colonisation rates several-fold in real people. A varied, plant-rich diet supports the same kind of microbial diversity this research ties to a more protective skin bacterial community. That's the same idea behind GutLab, everyday gut health starts with regularly feeding the microbiome a broad range of plant-rich ingredients.