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For further information, see CMDT Part 33-04: Staphylococcus Aureus Infections

Key Features

  • Localized erythema with induration and purulent drainage

  • Abscess formation

  • Folliculitis commonly observed

  • Gram stain of pus shows gram-positive cocci in clusters; cultures usually positive

Clinical Findings

  • May begin around one or more hair follicles, causing folliculitis

  • May become localized to form boils (or furuncles)

  • May spread to adjacent skin and deeper subcutaneous tissue (ie, a carbuncle)

  • Deep abscesses involving muscle or fascia may occur, often in association with a deep wound or other inoculation or injection

  • Necrotizing fasciitis has been reported with community strains of methicillin-resistant S aureus (MRSA)


  • Cultures of the wound or abscess material almost always yields the organism

  • In patients with systemic signs of infection, blood cultures should be obtained because of potential bacteremia, endocarditis, osteomyelitis, or metastatic seeding of other sites

  • Patients who are bacteremic should have blood cultures repeated every 24–48 hours during therapy to exclude persistent bacteremia, an indicator of severe or complicated infection


  • Proper drainage of abscess fluid or other focal infections is the mainstay of therapy

  • Incision and drainage alone is highly effective for the treatment of most uncomplicated cutaneous abscesses

  • A small benefit can be obtained from the addition of antimicrobials following incision and drainage (Table 33–1)

  • In areas where methicillin-resistance among community S aureus isolates is high, recommended oral antimicrobial agents include clindamycin, trimethoprim-sulfamethoxazole, doxycycline, or minocycline

  • When the risk of methicillin resistance is low or methicillin susceptibility has been confirmed by testing of the isolate, consider dicloxacillin or cephalexin

  • Treatment for 5–7 days is sufficient in most cases

  • For complicated infections with extensive cutaneous or deep tissue involvement or fever, initial parenteral therapy is often indicated

    • When methicillin resistance rates are high (> 10%), empiric therapy with vancomycin is a drug of choice

    • For infections caused by methicillin-susceptible isolates

      • Cefazolin, 1 g intravenously or intramuscularly or

      • A penicillinase-resistant penicillin such as nafcillin or oxacillin in a dosage of 1.5 g intravenously every 6 hours

  • For treatment of skin and skin-structure infections

    • Linezolid, 600 mg orally or intravenously twice a day for 10–14 days

      • Effective for MRSA

      • However, considerable cost makes it an unattractive choice for most routine outpatient infections

    • Other alternatives see Table 33–1

  • Duration of therapy

    • Total duration of therapy for soft tissues infections will depend on clinical response and effectiveness of drainage/debridement

    • Courses of 7 days with early transition to oral therapy are effective in many cases

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