Supplementary Material for: Temporal Variation in Staphylococcus aureus Protein A Genotypes from Nose and Skin in Atopic Dermatitis Patients

Background: Staphylococcus aureus colonization is associated with disease severity in patients with atopic dermatitis (AD). Objective: To investigate temporal variation in S. aureus protein A gene (spa)-types isolated from the nose and lesional skin and the correlation of spa-types with disease severity. Results: This study included 96 adult AD patients who were assessed at baseline (T0) and after a strict 2-week follow-up period (T1) in which treatment was standardized with a topical corticosteroid. Fifty-five different spa-types were detected in the nose and skin cultures. Seventy-three patients were colonized with S. aureus in the nasal cavity at both time points (persistent carriership), 59 of whom (81%) had identical spa-types over time. For skin samples, 42 (75%) of the 56 persistent skin carriers had identical spa-types over time. The same spa-type was carried in the nose and skin in 79 and 77% of the patients at T0 and T1, respectively. More severe disease was not associated with specific spa-types or with temporal variation in spa-type. Conclusion: S. aureus strains in AD are highly heterogeneous between patients. The majority of patients carry the same spa-type in the nose and skin without temporal variation, suggesting clonal colonization within individual patients. No predominant spa-type or temporal variation is associated with increased disease severity.