Common Skin Infections

Scarlet fever is caused by Strep pyogenes (a Group A strep) usually from a sore-throat, which produces a toxin. There is fever, then 1-2 days later, punctate erythema progressing to erythroderma (mild purpura in skin creases and perioral sparing is characteristic). Mucosal erythema is common. By day 7-10 skin shedding occurs. It can occasionally be very severe and coma and myocarditits have been reported. Complications also include suppurative: arthritis, meningitis, and osteomyelitis. Fortunately it is much less common than in the last century and also less severe. Treatment - penicillin and supportive care.

Scarlet fever

Meningococcal disease

Although this is not a skin disease as such, the presence of purpura on the skin is such an important clinical sign not to be missed that I feel duty bound to include it in this chapter. Remember your patient may be feverish, have a headache and photophobia but they may not look unduly unwell at the beginning so LOOK AT THE SKIN very carefully all over.

Clinical Tip: Meningococcal purpura, unlike a leucocytoclastic vasculitis which tend to favour the lower legs, can occur anywhere on the body, with non blanching often irregularly shaped purpuric or dusky skin changes.

Meningococcal sepsis- note non blanching irregularly shaped purpura