Phages in Dermatology: What Is Their Role?

Phages have great potential in dermatology to revolutionize the treatment of bacterial-induced diseases such as acne and atopic dermatitis. They also could be used to improve cosmetic issues, such as body odor. What exactly are phages? Quite simply, they are viruses that infect bacteria. How could they be used in dermatology? For example, you use a phage that infects and destroys Cutibacterium acnes. The phage, which is harmless to humans, could be spread over the face, killing C acnes and improving acne without the use of oral or topical antibiotics. This would prevent damage to the microbiome and minimize antibiotic resistance. The phage could also kill odor-causing bacteria in the intertriginous areas of the body, advancing deodorant science. Let’s take a deeper dive into phages and phage technologies.

The word phage is short for bacteriophage. DNA and RNA phages are available that only kill bacteria and are harmless to humans, animals, and plants. They are naturally occurring viruses found in water, soil, and sewage; however, phages are also found in the human mouth (dental plaque and saliva), the gut, and on the skin. In short, phages are found anywhere bacteria exist, which is just about everywhere.

Phages can keep the skin microbiome in check, preventing dysbiosis, a characteristic of skin disease, but they are also responsible for bacterial resistance to antibiotics, such as the resistance currently seen to erythromycin in C acnes. The community of phages infecting a certain environment is known as a phageome. Abnormalities in the phageome have been implicated in dermatologic conditions, such as acne, atopic dermatitis, psoriasis, and hidradenitis suppurativa, but no phage-based therapies have been approved by the FDA. From a cosmetic standpoint, phages might also be able to control bacterially derived genital, armpit, and foot odor, representing a tremendous advancement in deodorant efficacy. It may not be necessary to have a specific phage for each bacterium in a given body area, as phage diversity appears to be important for skin health. Thus, applying a phage cocktail might be sufficient. This theoretically could be applied to the body as a lotion after bathing to maintain phage diversity, prevent bacterial disease, and provide long-lasting odor control. An intriguing thought.

There are several considerations for phage therapy in dermatology. The first is whether the phages will proliferate on the skin surface. Ideally, you would apply bacteria-killing phages to the skin once, and they would persist over time, which is a form of active phage therapy. However, it appears that passive phage therapy, in which phages are continually applied in sufficient numbers to kill pathogenic bacteria, is more realistic. Not all phages are innocuous; they can be immunogenic and may produce toxins. For example, botulinum toxin is produced by a phage. Phages kill bacteria by releasing endotoxins that can be proinflammatory in humans. Phages are also pH sensitive, with lower pH products, which are used to maintain the skin acid mantle, decreasing phage titers. Finally, bacteria can mutate so they are no longer phage sensitive, making the phages inactive.

Much research remains to be done in phage science. Challenges remain in developing phage vehicles, administration methods, and dosing. Demonstrating efficacy is also somewhat challenging. Because phages may be considered as cosmetic ingredients at present, acne claims cannot be made on phage-containing acne treatment products. For this reason, some manufacturers add salicylic acid to acne products to make acne claims based on the acne monograph. It is then unclear whether the acne improvement is due to salicylic acid or the phage. Nevertheless, phages could revolutionize the treatment of bacterial skin conditions, but their potential has yet to be realized.

Zoe Diana Draelos, MD, is a clinical faculty member in the Department of Dermatology at Duke University School of Medicine in Durham, North Carolina; president of Dermatology Consulting Services in High Point, North Carolina; and Dermatology Times’ editor in chief emeritus.