The Effect of UVB Radiation on Skin Microbiota in Patients with Atopic Dermatitis and Healthy Controls

Objectives: To investigate Staphylococcus aureus and Staphylococcus epidermidis quantitatively in adult patients with atopic dermatitis and in healthy controls treated with UVB radiation.

Study Design: Twenty-three adult patients (of these, 3 were excluded) with flexural atopic dermatitis and 20 healthy controls were randomly selected at the outpatient clinic of the Dermatological Department, University Hospital, North Norway.

Methods: Adult patients with atopic dermatitis (n = 20) and healthy controls (n = 20) were given 20 UVB treatments. Bacterial samples were collected before treatment, after 4 weeks of treatment, and finally after 2 weeks follow-up.

Results: The main bacteria found were Staphylococcus aureus and Staphylococcus epidermidis. 16 of the 20 patients with atopic dermatitis had Staphylococcus aureus in lesional skin and 12 in non-lesional skin. None of the healthy controls had Staphylococcus aureus in the sample from the flexural elbow. The Staphylococcus aureus counts decreased (not significant) in lesional skin after 4 weeks of treatment and Staphylococcus aureus counts were slightly higher after 2 weeks follow up. The same figures were also seen in non-lesional skin and forehead.

Conclusions: Staphylococcus aureus is widely colonised in the skin of atopic dermatitis patients, but is rare in healthy adults. UVB treatment decreases the Staphylococcus aureus count in patients with atopic dermatitis.