Changes in the Scalp Microbiome in Alopecia Areata

Different Organisms Found on the Skin in Alopecia Areata

It has been estimated that every square centimeter of human skin normally has about 1 billion organisms. This includes bacteria, viruses and fungi. There is nothing abnormal about this - it’s simply part of being human. We share our skin with many microorganisms in the world around us. We call this normal population of organisms the “skin microbiome.” When the constitution of these organisms change, we say that there has been ‘microbial dysbiosis.

Microbial Dysbiosis in Alopecia Areata

The topic of microbial dysbiosis has become increasingly popular. In many fields of medicine, experts are examining changes in bacteria as a means to explain disease pathophysiology. The two most common areas of exploration are the gut and skin. Changes in the normal populations of organisms in the gut and skin are believed to play a role in certain diseases.

Whether or not “microbial dysbiosis” plays a role in scalp disease is actively being researched. A recent study from Milan showed that patients with alopecia areata indeed had a change in their scalp microbiome. The study showed an increase in Propionibacterium, a decrease in Staphylococcus epidermidis and no change in Staphylococcus aureus. The analysis specifically showed an increase of Propionibacterium from 45.6% to 55.1% in AA subjects. Alongside data showed a general decrease of Staphylococcus epidermidis from 32.6% to 27.4% .


This is one of the first studies to now focus on changes in the skin microbiome and how this relates to skin disease. The precise significance of the information is not clear. However, it should be noted that Pacnes is able to synthesize many enzymes involved in the metabolism of porphyrins that, once activated, may contribute to oxidation and follicular inflammation.


Pinto D et al. Scalp bacterial shift in Alopecia areata. PLoS One. 2019 Apr 11;14(4):e0215206. doi: 10.1371/journal.pone.0215206. eCollection 2019.

Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887

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