Sixty-one psoriatic patients were studied with regard to the quantities of Staphylococcus aureus on involved and uninvolved skin. About 50% of the patients carried S aureus, usually in low numbers. Staphylococcus aureus and resident cocci were more numerous on the lesions as compared to uninvolved skin.
Occlusion with plastic film led to an explosive increase of S aureus in carriers, accompanied by aggravation of inflammation. Heavily colonized lesions responded less well to treatment. Because of increased exfoliation, psoriasis is an important source of hospital cross infection.
Marples RR, Heaton CL, Kligman AM. Staphylococcus aureus in Psoriasis. Arch Dermatol. 1973;107(4):568-570. doi:10.1001/archderm.1973.01620190044010