A 19-year-old male has a history of athlete's foot but is otherwise healthy when he develops the sudden onset of fever and pain in the right foot and leg. On physical exam, the foot and leg are fiery red with a well-defined indurated margin that appears to be rapidly advancing. There is tender inguinal lymphadenopathy. The most likely organism to cause this infection is
(Braunwald, 15/e, pp 823, 893.) Erysipelas, the cellulitis described, is typical of infection caused by S.Pyogenes - Group A b- hemolytic Streptococci (GAS). There is often a preceding event such as a cut in the skin, dermatitis, or superficial fungal infection that precedes this rapidly spreading cellulitis. Anaerobic cellulitis is more often associated with underlying diabetes. S. epidermidis does not cause rapidly progressive cellulitis. Staphylococcus aureus can cause cellulitis that is difficult to distin guish from erysipelas, but it is usually more focal and likely to produce furuncles, or abscesses.
Staphylococcus epidermidis
Tinea pedis
Streptococcus pyogenes
Mixed anaerobic infection