Belirlenen Dermokozmetik Ürünlerin Cilt Florasını Oluşturan Bakterileri Popülasyonu Üzerindeki Etkisi

Introduction and Aim: Staphylococcus epidermidis and Staphylococcus aureus, essential components of the skin microbiota, play a critical role in maintaining the integrity of the skin barrier. In recent years, with the widespread use of dermocosmetic products, the indiscriminate application of active ingredients in these products can positively or negatively affect the skin microbiota. In particular, the sensitivity of sunscreens and light-sensitive vitamin A and C serums to their ingredients can potentially have harmful effects on the colony formation and morphology of these bacteria. Staphylococcus epidermidis, naturally present in the skin, contributes to strengthening the skin barrier and preventing water loss by increasing ceramide production. Therefore, it is defined as a barrier-supporting commensal strain. A decrease in its numbers can lead to reduced ceramide production, weakened skin barrier, increased water loss, and disruption of the immune balance, potentially causing skin problems such as inflammation. In contrast, Staphylococcus aureus is a classic pathogenic strain that produces harmful toxins, can form biofilms, and activates the immune system, leading to an increase in pro-inflammatory cytokines. These effects can exacerbate barrier disruption, particularly in skin diseases such as atopic dermatitis. Therefore, a decrease in the number of S. aureus in the skin flora is considered positive in terms of reducing inflammation and protecting the skin barrier. This study aims to investigate the effects of applying selected sunscreens and serums containing vitamins A and C, directly and/or through sun exposure, on the colony formation of S. epidermidis and S. aureus bacteria, which are naturally present in the skin flora, under suitable culture media conditions. In the experimental setup, cosmetic products will first be applied to the culture media, followed by bacterial treatment. In this way, the positive or negative effects of the relevant products on the bacteria will be evaluated, and the risks or benefits in terms of skin health will be revealed. Materials and Methods: The experimental setup used commercially available dermocosmetic sunscreens, vitamin C serums containing 4% and 10% ascorbic acid, and vitamin A serums containing 2% and 5% retinol. First, the products to be tested were applied to LB agar, a suitable medium for bacterial growth, by spreading. Then, S. epidermidis and S. aureus bacteria were spread using a spreader. Petri dishes were incubated in an incubator at 37°C for 16 hours. Experimental applications were performed with at least three independent replicates for each product and each bacterium. Results and Conclusion: In response to the tested dermocosmetic product treatment, the colony count of the S. epidermidis strain increased compared to the control group. This increase and proliferative responses suggest that these products may have the potential to support the microbiota, contribute to the protection of the skin barrier, and strengthen the skin barrier and prevent water loss by increasing ceramide production. The colony count of the S. aureus strain decreased significantly after all dermocosmetic product treatments. This indicates that the active ingredients in the products used exert a suppressive or antimicrobial effect on S. aureus, suggesting that the products may cause selective toxicity to this bacterium. Furthermore, the decrease in the colony count of S. aureus, a bacterium commonly found in the skin flora and whose increased numbers are associated with acne formation, demonstrates that the dermocosmetic products also have an effect aimed at protecting the skin barrier.