Infections of the skin

Abstract

A huge variety of different organisms exist on healthy skin, the normal microbiome. Under certain circumstances, microbes can actively infect the skin as a primary or secondary event in cutaneous or systemic disease. The most common causes of bacterial infection of the skin are Staphylococcus aureus or β‎-haemolytic streptococci. There are increasing reports of both hospital- and community-acquired infection by methicillin-resistant S. aureus. Mycobacterium tuberculosis remains a common skin infection in many tropical areas, and syphilis, leprosy, and leishmaniasis are important skin infections in some parts of the world. Dermatophytosis, or ringworm, is caused by mould fungi that can digest keratin (keratinophilic). The diagnosis can be confirmed in the laboratory by examining scrapings or clippings of skin, hair, or nails mounted in potassium hydroxide. Occasionally, in the immunocompromized patient these and other herpes virus infections can disseminate, both to other parts of the skin as well as internally.