Characterisation of Staphylococci Associated with Atopic Eczema and Chronic Plaque Psoriasis

Abstract

Though well characterised diseases of the skin, the causes of atopic eczema and chronic plaque psoriasis have yet to be elucidated. The association of S.aureus in eczema and group A beta-haemolytic streptococci in psoriasis, have been well documented, however, the role of coagulase-negative staphylococci (CNS) has been largely understudied. In this investigation, the skin flora of ten patients with atopic eczema and ten patients with chronic plaque psoriasis was quantitatively assessed. The staphylococci isolated were identified by conventional techniques and by the molecular technique of pulsedfield gel electrophoresis (PFGE). Blood samples were obtained from each patient and ten control patients to test for antibody levels to gram-positive organisms by means of a novel ELISA which incorporates a short chain lipoteichoic acid, lipid S. This test has been of value in detecting patients with sepsis due to Gram-positive cocci and was used in this study to determine whether the organisms on the skin surface produce an immune response. Psoriatic skin consisted of many different species and genotypes of CNS, with no one strain being associated with the condition. Many different genotypes of CNS were also identified from eczematous skin but S.aureus was by far, the most predominant organism. Each patient had their own unique strain of S.aureus, which could be reisolated from different areas at different times and thus in contrast to the CNS from both diseases, was a constant entity. The S.aureus isolates from eczematous skin were tested for superantigen production and certain enzymes, however, the results were inconclusive and as with the PFGE results, no common strain was found for all...