Chapter 90. Soft Tissue Infections

Patients with soft tissue infections present frequently to the emergency department (ED). The management of these infections involves an understanding of appropriate antibiotic treatment, outpatient or inpatient treatment options, and an understanding of when surgical intervention is necessary.

Community-acquired MRSA is epidemic across all populations. A significant majority of soft tissue infections in adults and children are caused by community-acquired MRSA. Understanding the treatment of community-acquired MRSA is vital for those managing soft tissue infections in the ED.

Clinical Features

Community-acquired MRSA is a frequent cause of skin and soft tissue infections. Lesions are typically warm, red, tender, and may be draining a purulent fluid. MRSA lesions are frequently mistaken as spider bites by patients as well and clinicians.

Diagnosis and Differential

The diagnosis of MRSA is largely clinical. Community-acquired MRSA should be considered in any infection where S aureus or Streptococcus is typically considered the etiologic agent. This includes skin and soft tissue infections as well as sepsis and pneumonia. Bedside ultrasound is helpful to identify abscess collections in equivocal cases.

Emergency Department Care and Disposition

1. For many community-acquired MRSA cutaneous infections, adequate incision and drainage (I&D) is adequate to manage these infections. Suggested criteria for withholding antibiotics include: abscesses that are small < 5 cm, abscesses in immunocompetent patients, and abscesses without accompanying cellulitis.

2. If local epidemiology supports MRSA as the likely etiology of cellulitis, antibiotics effective against MRSA should be given. These include clindamycin 300 milligrams PO 4 times daily or trimethoprim/sulfamethoxazole double strength 1 to 2 tablets twice a day for 7 to 10 days. Consider adding Cephalexin 500 milligrams 4 times daily to a regimen with trimethoprim/sulfamethoxazole to cover streptococcus. If the infection is severe, vancomycin 1 gram every 12 hours should be used, and inpatient therapy is indicated.

3. Patients who are at the extremes of age, have fever, significant comorbidities, or have a large number of lesions may require admission for parenteral antibiotics.

Necrotizing soft tissue infections are a spectrum of conditions that may be polymicrobial or monomicrobial. Group A Streptococcus and S aureus are often the etiologic agent in monomicrobial infections. Clostridial infections are now uncommon secondary to improved hygiene and sanitation.

Clinical Features

Patients present with pain out of proportion to physical findings and a sense of heaviness in the affected part. Physical findings typically include a combination of edema, brownish skin discoloration, bullae, malodorous serosanguineous discharge, and crepitance. The patient frequently has a low-grade fever and tachycardia out of proportion to the fever. Mental status changes, including delirium and irritability, may accompany necrotizing soft tissue infections.

Diagnosis and Differential

Familiarity with the disease and an appreciation of the subtle physical findings are the most important factors in making the diagnosis of necrotizing soft tissue infections. Additional findings that may confirm the clinical suspicion include gas within soft tissue on ...