Background and design: Colonization of inflammatory skin diseases with Staphylococcus aureus is a frequent phenomenon and may cause exacerbation of the skin disease. Staphylococcus aureus strains present on atopic dermatitis are capable of releasing staphylococcal enterotoxins, a group of superantigens that are very potent T-cell activators. To determine whether the superantigen staphylococcal enterotoxin B can induce inflammation when applied on the skin, staphylococcal enterotoxin B was applied with and without occlusion on the volar aspect of the skin on the forearm of 10 subjects without skin disease and six subjects with atopic dermatitis of minimal activity and no eczema on the volar aspect of the skin on their forearm. The main outcome measures were clinical rating; determination of the increase of the thickness of the skin-fold; and determination of skin blood flow.
Results: Clinically, staphylococcal enterotoxin B induced skin changes of erythema and induration in 10 of 10 healthy volunteer subjects and six of six subjects suffering from atopic dermatitis, while the vehicle induced clinically evident skin changes in only one of 10 healthy subjects and none of six subjects with atopic dermatitis. On day 3 after the application of an occluded patch containing 10 micrograms/cm2 of staphylococcal enterotoxin B in the healthy subjects, the thickness of the skinfold increased 0.47 +/- 0.49 mm (mean +/- SD) (n = 9; P < .02) relative to the increase in the thickness of the skinfold following application of the vehicle. The Doppler laser-measured skin blood flow index had increased from 1.0 +/- 0.4 to 5.3 +/- 3.7 (mean +/- SD) (n = 10; P < .002). On day 3 after the application of occluded patchs containing 10 micrograms/cm2 of staphylococcal enterotoxin B in the subjects suffering from atopic dermatitis, the increase in the thickness of the skinfold increased 0.20 +/- 0.24 mm (n = 6; P, not significant) relative to the increased thickness in the skinfold following application of the vehicle. The Doppler laser-measured skin blood flow index had increased from 1.1 +/- 0.4 to 3.7 +/- 2.2 (n = 6, P, not significant). Three of six subjects suffering from atopic dermatitis experienced a flare of their disease in the elbow flexure ipsilaterally to where the staphylococcal enterotoxin B patch was applied.
Conclusions: The superantigen staphylococcal enterotoxin B applied on intact skin from both normal subjects and patients with atopic dermatitis induces an inflammatory reaction. This finding suggests that superantigens released from S aureus present on the skin in inflammatory skin diseases may exacerbate and sustain the inflammation.