Staphylococcus aureus, Skin & Soft Tissue Infections

Localized erythema with induration and purulent drainage

Abscess formation

Gram stain of pus shows gram-positive cocci in clusters

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 taken early 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.

In areas where methicillin-resistance among community S aureus isolates is high, recommended oral antimicrobials agents include

• Clindamycin, 300 mg three times daily

• Trimethoprim-sulfamethoxazole, given in two divided doses based on 5–10 mg/kg/day of the trimethoprim component

• Doxycycline or minocycline, 100 mg twice daily

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

• Dicloxacillin or cephalexin, 500 mg four times a day

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

When methicillin resistance rates are high (above 10%) empiric therapy with vancomycin, 1 g intravenously every 12 hours, 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 every 6 hours intravenously

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

  • Tedizolid, 200 mg orally once daily for 6 days

  • Daptomycin, 4 mg/kg once daily intravenously for 7–14 days

  • Tigecycline, 100 mg intravenously once, followed by 50 mg intravenously twice a day for 7–14 days

  • Ceftaroline, 600 mg intravenously twice a day for 7–14 days

  • Dalbavancin, a single intravenous dose of 1500 mg

  • Oritavancin, 1200 mg as a single intravenous dose

  • Telavancin, 10 mg/kg intravenously once daily for 7–14 days

  • Delafloxacin, 450 mg orally or 300 intravenously twice daily for 5–14 days

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