Erysipelas is a bacterial infection of the dermis and upper subcutaneous layer, usually caused by streptococcus pyogens (β-haemolysis Lancefield Group A streptococcus) but also can be caused by β-haemolysis Lancefield Group G streptococcus and Staphylococcus aureus. It usually affects any part of the skin particularly face, legs and feet. The lesion is well raised, demarcated, red, swollen, tender and may develop vesicles and bullae. Symptoms include headache, fever, fatigue and the rapid enlargement of the skin redness
Erysipeloid is a rare cutaneous inflammatory infection in humans caused by Erysipelothrix rhusiopathiae. It usually affects the hands of persons who handle fish and raw meat. The lesion is raised, violaceous in colour with the absence of pus and usually accompanied by itching and burning. The absence of pus usually helps to differentiate it from Staphylococcal and Streptococcal skin infection. E. rhusiopathiae is a Gram positive rod which grows on blood agar, producing small, transparent glistering colonies and may be α-haemolytic. It also grows on Triple sugar iron agar (TSI) producing hydrogen sulphide turning the TSI butt black. They are microaerophlic and facultative anaerobes.