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.