High-frequency devices effect in vitro: promissing approach in the treatment of acne vulgaris?

Acne vulgaris is an inflammatory skin disorder leading to an impairment of quality of life and is therefore not only a cosmetic issue. Its pathogenesis is multifactorial - of particular importance is the colonization with the bacterium Propionibacterium acnes. A wide range of different treatment options exists including topical and systemic treatments depending on severity. High Frequency (HF) therapy, historically developed in the 19^th century, claims antimicrobial effects on acne skin, but solid data on its efficacy and mechanism of action is lacking.

The main objective of this study was to determine the efficacy of HF therapy on skin flora and P. acnes in vitro using a commercial device as well as to review studies on the mechanism of action.

The plasma source was investigated regarding electrical settings, heat, and ozone development. Bacterial skin flora, fungal isolates, and P. acnes were exposed to HF in vitro and compared to unexposed controls by evaluating the number of colonies on agar plates. To further analyze bacterial species from normal skin flora, 16S-sequencing was performed. Statistical analyses were carried out using row analysis and unpaired t-test.

HF treatment led to a significant reduction of almost every bacterial and fungal species investigated in this study. Moreover, the number of colonies forming units was significantly decreased in P. acnes after HF treatment compared to controls in vitro.

The experiments were performed in vitro only. To assess clinical effects further in vivo experiments are necessary.

The results collected in this study, although in vitro, provide a mechanistic basis for HF as a complementary treatment option for patients with acne. It might also have a beneficial effect on patients with superficial infectious skin of the skin.