Evidence for the presence of bacteria in the blood of psoriasis patients.

Evidence exists that microorganisms, particularly in the throat and skin, play a role in the pathogenesis of psoriasis. The aim of this study was to investigate whether evidence for the presence of bacteria, including Streptococcus pyogenes, can be demonstrated in the peripheral blood of patients with guttate and/or chronic plaque psoriasis. Peripheral blood samples from 20 patients with psoriasis, seven guttate, six chronic plaque and seven chronic plaque with associated guttate flare and from 16 control subjects were studied for the presence of bacteria by PCR using universal 16S ribosomal DNA primers and specific primers for S.