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Pilot study finds a more diverse microbiome in preadolescents with acne, compared with controls

Key clinical point: The preadolescent skin microbiome shows some differences to that of adults with acne, which may have treatment implications.

Major finding: The skin microbiome was more diverse among preadolescents with acne, compared with age-matched controls without acne, and Streptococcus was the predominant bacterium.

Data source: A prospective randomized pilot study that evaluated the skin microbiome of five preadolescents with acne, before and after treatment, and eight without acne.

Disclosures: The study was supported with a grant from the American Acne and Rosacea Society.

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The cutaneous microbiome and acne: Adult versus pediatric skin

Recent work has highlighted distinct differences in the cutaneous microbiota of acne sufferers versus those who tend not to “break out,” specifically, decreased bacterial diversity, increased Propionibacterium acnes and Staphylococcus aureus, and importantly, specific ribotypes of P. acnes (not all P. acnes is created equal in the eyes of acne vulgaris). There are also emerging data highlighting the impact of both topical and systemic acne medications on this altered bacterial community, though the significance of such changes has yet to be determined. However, these findings are predominantly derived from the adult population, and just as pediatric skin is not just little adult skin, acne can be morphologically different in this population. And no question, the microbiota here is different from adults.

In their pilot study, Coughlin et al. set out to evaluate the alterations in cutaneous microbiota in adolescents with acne versus healthy controls. Interestingly, as opposed to adults, adolescent acne sufferers have greater bacterial diversity, with a high predominance of streptococcus in addition to P. acnes and S. aureus. No surprise, benzoyl peroxide brought diversity down as it is “-cidal” to everything (even our cells).

While a small sample size, two big questions emerge from this study: Why does bacterial diversity increase in pediatric acne patients but decreases in adults with acne? And what is the significance of streptococcus in pediatric acne? Certainly, the clinical morphology of pediatric acne (more comedonal as per the authors) is different than that of adult female acne (cystic and clinically inflamed nodules), for example. Do specific alterations in the skin microbiome directly impact lesion type? We shall see.

Adam Friedman, MD, is residency program director, and director of translational research, in the department of dermatology, George Washington University, Washington. He had no relevant disclosures. Dr. Friedman is a member of the Dermatology News editorial board.



The skin microbiome in preadolescents with acne was more diverse than that of controls, and showed some differences from what is known about the microbiome in adults with acne, in a prospective pilot study.

The results have possible treatment implications, suggesting that preadolescents may require a different treatment approach than adults, although additional, larger studies are needed, according to Carrie C. Coughlin, MD, of the division of dermatology in the departments of medicine and pediatrics at Washington University in St. Louis, and her coauthors (Pediatr Dermatol. 2017 Oct 11. doi: 10.1111/pde.13261).

The study enrolled 13 children aged 7-10 years: 5 with acne (3 randomized to treatment with benzoyl peroxide 5% gel or cream and 2 to treatment with tretinoin 0.025% cream), treated for 7-10 weeks; and 8 controls, matched for sex and age.

At baseline, microbiome samples of facial and retroauricular skin among the controls with no acne showed that Streptococcus “was the genus present in highest relative abundance, followed by Propionibacterium,” the authors wrote. In addition to high levels of Streptococcus, those with acne also “had more Staphylococcus and Propionibacterium than controls at all sites before treatment.”

Among those with acne, average Comprehensive Acne Severity Scale values at baseline were 1.3-1.4, among those with acne, dropping to an average of 1 with treatment, which was not statistically significant at follow-up.

But among those with acne, the diversity of cutaneous bacteria decreased with both treatments, down to levels similar to controls, which was a significant effect (P less than .001). This was a “notable” finding, they wrote, “because benzoyl peroxide and tretinoin are known as comedolytic, but tretinoin is not typically thought of as having antibacterial properties like benzoyl peroxide.”

This observation “suggests that topical retinoids may have an effect on the local microbiome through alterations in the cutaneous microenvironment rather than having direct effects on resident microorganisms,” they added.

The authors also pointed out that in the microbiome of adults with acne, Propionibacterium has been found to be more prevalent, indicating that different treatments may be indicated in preadolescents.

The study was funded with a clinical research grant from the American Acne and Rosacea Society.

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