In which of the following conditions is an infectious agent not implicated?
a) pustular psoriasis _ _ _ _ _ _ _ _ _ _ Correct ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ b) furuncle _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ c) impetigo _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ d) erysipelas _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ e) erythrasma _ _ _ _ _ _ _ _ _ _ Wrong answer ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ Answer and Commentary _ _ _ _ _ _ _ _ _ _ In all except (a) an infectious agent is implicated. Pustular psoriasis lesions are a result of invasion of epidermis by neutrophils and cultures are sterile. Staphylococcus aureus is commonly the causative agent in furuncles (a perifollicular inflammatory nodule) and impetigo (a superficial vesical pustular skin infection commonly seen in children). a superficial cellulitis, is caused by group A B-hemolytic streptococci. Erythrasma, also a superficial skin infection is caused by Corynebacterium minutissimum and is found commonly in adults and diabetics. Skin infections respond promptly to systemic antibiotics although the newer topical antibiotics such as fusidic acid and mupirocin have been shown to be equally as effective in localized infections. ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯ ¯
