Nasal methicillin-resistant Staphylococcus aureus in adult atopic dermatitis: Severity and virulence associations-A cross-sectional study

ObjectivesTo investigate the prevalence of nasal methicillin-resistant Staphylococcus aureus (MRSA) colonization among adults with atopic dermatitis and explore its association with disease severity.MethodsThis cross-sectional study included 100 adults (≥18 years) with dermatologist-confirmed atopic dermatitis who attended dermatology outpatient clinics in Kuwait. Patients with nonatopic eczema, major systemic illnesses, or skin malignancy were excluded. Disease severity was assessed using the validated Investigator's Global Assessment for Atopic Dermatitis. Nasal swabs were collected, and S. aureus isolates were identified using culture, Gram staining, and catalase and coagulase tests, followed by confirmation using the VITEK® 2 system. Methicillin resistance (mecA) and selected staphylococcal virulence genes, including the classical (sea, seb, sec, sed, and see) and nonclassical staphylococcal enterotoxins (seg, seh, and sei), Panton-Valentine leukocidin (pvl), and toxic shock syndrome toxin-1 (tsst-1) were determined using polymerase chain reaction. Antimicrobial susceptibility profiles were assessed using the Clinical and Laboratory Standards Institute disk diffusion method.ResultsS. aureus colonization is a key feature of atopic dermatitis and is closely associated with disease activity. This study investigated the prevalence of nasal MRSA colonization among adults with atopic dermatitis and examined its association with disease severity and virulence gene carriage. Overall, 53% of patients were colonized with S. aureus, of whom 71.7% carried MRSA. MRSA colonization was significantly associated with older age and greater disease severity. Virulence gene analysis in MRSA isolates revealed higher frequency of seg and sei, whereas the presence of sea and tsst-1 were significantly associated with more severe atopic dermatitis.ConclusionsAdults with atopic dermatitis showed a high prevalence of nasal MRSA colonization. The predominance of enterotoxin gene cluster genes and the association of sea and tsst-1 with greater disease severity highlight the potential clinical importance of nasal MRSA as a reservoir of virulent strains in atopic dermatitis.