++
For further information, see CMDT 33-01: Streptococcal Infections
++
Group A β-hemolytic streptococci are not normal skin flora
Usually result from colonization of normal skin by contact with other infected individuals or by preceding streptococcal respiratory infection
++
Impetigo
Focal, vesicular, pustular lesion with a thick, amber-colored crust that has a "stuck-on" appearance
Erysipelas
Painful superficial cellulitis that is well demarcated from the surrounding normal skin
Frequently involves the face
Affects skin with impaired lymphatic drainage, such as edematous lower extremities or wounds
++
Cultures obtained from skin are usually negative unless there is a wound, pustule, or impetigo, but if positive can help to exclude nafcillin-resistant streptococci
Blood cultures are occasionally positive
++
Parenteral antibiotics
Indicated for patients with facial erysipelas or evidence of systemic infection
Penicillin, 2 million units intravenously every 4 hours, is the drug of choice
For patients with risk factors for S aureus infection (eg, injection drug use, wound infection, diabetes) reasonable choices for initial therapy include
Nafcillin, 1–2 g intravenously every 4–6 hours, or
Cefazolin, 1 g intravenously or intramuscularly every 8 hours
In the patient at risk for methicillin-resistant S aureus infection or with a serious penicillin allergy (ie, anaphylaxis), vancomycin, 1000 mg intravenously every 12 hours, or daptomycin, 4 mg/kg intravenously daily, should be used (Table 33–1)
Patients who do not require parenteral therapy and in whom S aureus infection is less likely may be treated with amoxicillin, 500 mg orally three times daily or 875 mg orally twice daily for 7–10 days
A first-generation oral cephalosporin (eg, cephalexin, 500 mg orally four times daily), or clindamycin, 300 mg orally three times daily, is an alternative to amoxicillin
Maintenance therapy (for at least 1 year) with penicillin, 250 mg orally twice daily, may reduce the likelihood of relapse of recurrent cellulitis of the leg
++