Variation of Staphylococcus aureus Clonal Complex Type Linked to Worse Disease Activity in Atopic Dermatitis

In adult patients with atopic dermatitis (AD), a change in Staphylococcus aureus
clonal complex (CC)-type is linked to flare-ups and a higher diseases activity score, according to the results of a follow-up cohort study conducted at an outpatient clinic in Bispebjerg Hospital in Copenhagen, Denmark, published in the British Journal of Dermatology.

Recognizing that patients with AD are predisposed to developing skin infections with
S aureus, the investigators sought to examine the temporal variation in S aureus colonization and S aureus CC-type in patients with AD and to establish the association with disease severity, skin barrier properties, and filaggrin (FLG) gene mutations.

The current follow-up study involved a cohort of 101 adult patients with AD who were recruited from an outpatient hospital clinic. Bacterial swabs from lesional skin, nonlesional skin, and noses of the participants were taken at baseline and at follow-up. Swabs that were positive for S aureus were characterized by spa and by the respective CC-type assigned. Patients were differentiated with respect to disease severity (SCORAD [SCORing Atopic Dermatitis]); FLG gene mutations; and skin barrier properties, including transepidermal water loss (TEWL) and pH.

Of the 101 invited patients with AD, a total of 63 participated in the follow-up study. Mean participant age was 35.8±14.2; there were 35 women and 28 men. Overall, 42.9% of patients (27 of 63) were colonized at both visits, 42.9% of patients (27 of 63) at only 1 visit, and 14.3% (9 of 63)  not colonized at either visit. Of patients who were colonized at both visits, 51.9% remained colonized with the same CC-type at follow-up.

Overall, 54.0% of patients (34 of 63) were colonized with S aureus in ≥1 sample sites at follow-up. The prevalence of S aureus colonization in lesional skin, nonlesional skin, and the noses of these individuals was 33.3%, 9.5%, and 4.13%, respectively.

Change in a patient’s CC-type was associated with an increase in SCORAD of 10.7 points, compared with patients who carried the same CC-type and exhibited a reduction in SCORAD of 4.4 points. Moreover, significantly higher skin pH was detected in patients who were colonized at both visits, whereas change in CC-type was not related to pH, TEWL, or FLG gene mutations.

The investigators concluded that the fact that approximatelt half of patients remain colonized over time with the same CC-type suggests a constant colonization in a large group of individuals. Change in S aureus CC-type is related to increased disease severity.

Reference

Clausen M-L, Edslev SM, Nørreslet LB, Sørensen JA, Andersen PS, Agner T. Temporal variation of Staphylococcus aureus clonal complexes in atopic dermatitis – a follow up study [published online August 2, 2018]. Br J Dermatol. doi:10.1111/bjd.17033