184 Skin and Soft Tissue Infections
Key Points• Uncomplicated subcutaneous abscesses in otherwise healthy patients require incision and drainage alone, without antibiotic therapy.
• Cellulitis with induration may harbor a deep purulent collection despite the lack of fluctuance on physical examination. Ultrasound or needle aspiration may be used to assist in the search for areas of pus that require incision and drainage.
• Cellulitis with purulence should be treated with antibiotics that are active against community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), and cellulitis without purulence should be treated with antibiotics active against Streptococcus species.
• Patients with mild diabetic foot infections may be treated with oral agents that target gram-positive organisms, including CA-MRSA.
• Emergency physicians must always search for signs of necrotizing infection to exclude the deadly diagnosis early in the management of skin and soft tissue infections.
• Emergency consultation with a surgeon is mandated when a suspicion of necrotizing skin and soft tissue infection arises.
Community-Acquired Methicillin-Resistant Staphylococcus Aureus
Since the late 1990s, an epidemic of skin and soft tissue infections has been caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). Currently in the United States, CA-MRSA is the most common cause of skin and soft tissue infection in patients presenting to emergency departments. Patients who develop these infections have been previously healthy, and most have not been exposed to health care settings or prior antibiotic therapy.1
In 2011, the Infectious Disease Society of America released its long-anticipated first clinical guidelines for the treatment of MRSA infections, including CA-MRSA, in adults and children.1 The panel of experts provided an evidence-based framework for the clinical evaluation and treatment of skin and soft tissue infections and more invasive infections such as bacteremia and pneumonia.
Cellulitis
The pathogens of cellulitis are rarely identified in any particular patient, but they are thought to be primarily S. pyogenes (less commonly, other β-hemolytic streptococci such as groups B, C and G) and S. aureus. Culture of material aspirated from the involved skin is not routinely performed because of the invasive nature of the procedure and the low diagnostic yield. Blood cultures are of little value; only approximately 2% to 5% of these cultures yield results. A newer distinction has been proposed between nonpurulent cellulitis, which is believed to be more likely caused by Streptococcus species, and cellulitis that is associated with purulence and is probably caused by S. aureus. (See the later discussion of purulent skin infections.)
Purulent Skin Infections
Small, superficial pustular infections arising from the hair follicle are usually caused by S. aureus and are referred to as folliculitis. The lesions of folliculitis tend to be approximately 2 to 5 mm in diameter, they are isolated to the epidermis, and they generally produce pruritus rather than pain. Treatment consists of warm, moist compresses and topical antibiotic ointment, such as mupirocin. If systemic therapy is desired (because of a lack of response to topical therapy, extensive infection, or the presence of underlying immunocompromising medical condition), an agent active against CA-MRSA is recommended (Table 184.1).
Table 184.1 Antibiotics for Community-Acquired Methicillin-Resistant Staphylococcus aureus Skin Infections
| DEGREE OF INFECTION | ANTIBIOTIC REGIMEN |
|---|---|
| Mild | Trimethoprim-sulfamethoxazole (double strength) 1 PO bid Related posts: Stay updated, free articles. Join our Telegram channel
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