Sunscreens are a vital tool for protecting the skin from the damaging effects of ultraviolet radiation (UVR). The microbiome of the skin may play an important but poorly understood role in the susceptibility of skin to sun damage, suggesting it to be an avenue for the enhancement of future sunscreens. Despite this, the impact of sunscreens on the skin microbiome has received little research attention. We have investigated the effect of sunscreens on the viability of skin bacteria with and without exposure to UVR. Viable counts were done to measure the impacts of four sunscreens on the viability of Staphylococcus epidermidis, Staphylococcus capitis and Micrococcus luteus after 2 hours of exposure. The photoprotective effect of sunscreens towards bacteria irradiated with a dose of 100mJ/cm2 UVB was also measured using viable counts. The viability of all three species of bacteria exposed to sunscreens for 2 hours showed an average log reduction of 0.38 compared to those exposed to a water control. No statistically significant differences between the species or sunscreen type were identified. Viable bacteria following a single exposure to UVB decreased to 6.4% (± 1.5), 15.21% (± 3.9) and 53.0% (± 11.75) of the original inoculum concentration, for Staphylococcus aureus, Staphylococcus epidermidis and Micrococcus luteus, respectively. In the presence of sunscreen and UVB exposure, no reductions in viability were observed. This applied to all products tested with no significant differences between types of sunscreen or the species under test. This research suggests that sunscreens have a net protective effect on the bacteria tested, providing UVB protection while having little direct impact on viability after 2 hours of exposure.

ESDR525 - Sunscreens on the skin microbiome: Impacts on bacterial viability in the presence and absence of ultraviolet radiation

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.