A Prospective Cohort Study to Assess the Safety and Tolerability of Methods to Measure the Human Response to Skin and Soft Tissue Infection (DEFEND)

Staphylococcus aureus is a type of bacteria which commonly causes skin and soft tissue infections (SSTIs). These infections can range in severity from mild localised skin involvement to severe disease in which bacteria invade the bloodstream resulting in sepsis and poor outcomes. The number of SSTI cases caused by Staphylococcus aureus is increasing, and we currently have no vaccines to prevent infections. Treatment of infection often requires antibiotics although the effectiveness of these is at risk due to spread of antimicrobial resistance. Importantly, people who have one episode of SSTI are at much higher risk of similar future infections, for reasons that are not yet clear. How the human immune system responds to SSTI and the degree to which people might become more susceptible to future episodes is not well understood. Our research aims to understand the immune response to infection in patients who have recently experienced Staphylococcus aureus skin and soft tissue infection (SSTI) and compare it with healthy individuals. We will compare information and samples analysed from these two types of participants, to help us identify specific immune responses and how these differ between people recovering from infection. We will also investigate the structure and function of the skin, in particular its ability to heal. Understanding the nature of these immune responses, and in particular those occurring within the skin, may help in developing better treatments and preventative measures for skin infections in the future. The study has been designed with minimal risk and aims to contribute to advancing medical knowledge on immune responses to Staphylococcus aureus SSTI.