Patients with Atopic Dermatitis Colonized with Staphylococcus aureus Have a Distinct Phenotype and Endotype.

Abstract

Patients with atopic dermatitis (AD) are commonly colonized with Staphylococcus aureus (AD S.aureus+), but what differentiates this group from noncolonized AD patients (AD S.aureus-) has not been well studied. To evaluate whether these two groups have unique phenotypic or endotypic features, we performed a multicenter, cross-sectional study enrolling AD S.aureus+ (n= 51) and AD S.aureus- (n= 45) participants defined by the presence or absence of S.aureus by routine culture techniques and nonatopic, noncolonized control individuals (NA S.aureus-) (n= 46). Filaggrin (FLG) genotypes were determined, and disease severity (Eczema Area and Severity Index, Rajka-Langeland Severity Score, Investigator's Global Assessment score, Numerical Rating Scale, and Dermatology Life Quality Index) was captured. Skin physiology was assessed (transepidermal water loss [TEWL], stratum corneum integrity, hydration, and pH), and serum biomarkers were also measured. We found that AD S.aureus+ patients had more severe disease based on all scoring systems except itch (Numerical Rating Scale), and they had higher levels of type 2 biomarkers (eosinophil count, tIgE, CCL17, and periostin). Additionally, AD S.aureus+ patients had significantly greater allergen sensitization (Phadiatop and tIgE), barrier dysfunction (TEWL and stratum corneum integrity), and serum lactate dehydrogenase (LDH) than both the AD S.aureus- and NA S.aureus- groups. FLG mutations did not associate with S.aureus+ colonization. In conclusion, adult patients with AD who are colonized on their skin with S.aureus have more severe disease, greater type 2 immune deviation, allergen sensitization, barrier disruption, and LDH level elevation than noncolonized patients with AD.