Table 1_Anti-inflammatory effect of a Bacillus halotolerans DY299 strain isolated from Arshan on methicillin-resistant Staphylococcus aureus-induced atopic dermatitis in mouse.docx

Introduction<p>Methicillin-resistant Staphylococcus aureus (MRSA) colonization is a major contributor to atopic dermatitis (AD), and its rising resistance and virulence underscore the urgent need for novel antimicrobial strategies.</p>Methods<p>In this study, a halotolerant strain designated Bacillus halotolerans DY299 was isolated from Arshan water. The cell-free culture supernatant (DY299-CFS) was prepared and its anti-biofilm and antibacterial activities against MRSA were evaluated in vitro.

The therapeutic efficacy was assessed in an MRSA-induced AD mouse model, with skin lesion severity, stratum corneum hydration, mast cell infiltration, and cutaneous MRSA colonization examined. Serum levels of IgE, IL-13, IFN-γ, and IL-17 were measured by ELISA. To elucidate the molecular mechanisms, whole-genome sequencing of DY299, LC-MS/MS metabolomic profiling of its supernatant, transcriptomic analysis of skin tissues, and network pharmacology-based target prediction were integrated.</p>Results<p>DY299-CFS demonstrated significant anti-biofilm activity, achieving an inhibition rate of 50.93% and effectively eradicating MRSA biofilm both in vitro and in vivo.