- Soft tissue infections characterized by extensive necrosis of subcutaneous tissue, fascia, or muscle are uncommon, but they require prompt recognition and urgent surgical treatment.
- The classic hallmarks of virulent soft tissue infections are extensive involvement of the subcutaneous tissues and a relative paucity of cutaneous involvement until late in the course of the infection.
- Rapidly spreading soft tissue infections present acutely with severe systemic toxicity.
- Successful management of these critically ill patients depends on prompt diagnosis by clinical and radiologic means.
- The principles of management include fluid resuscitation, hemodynamic stabilization, a broad-spectrum antimicrobial regimen, and early surgical intervention.
- Prompt surgery, in which a definitive diagnosis is reached and all necrotic tissue is débrided, should be considered the mainstay of treatment.
- The mortality rate is highest when the diagnosis is delayed or initial surgical treatment is limited.
In severe soft tissue infections, the initial cutaneous presentation often belies the relentless progression of subcutaneous tissue necrosis and dissection that lies beneath a normal-appearing skin. Successful management of these soft tissue infections depends on early recognition followed by appropriate investigations to establish a specific diagnosis. A clear understanding of a classification of these entities is required, but, unfortunately, the published literature in this area is confusing because of a lack of uniformity in descriptive terminology and the use of different classification schemes. The confusion is compounded by the fact that certain clinical entities may involve one or more anatomic planes within the subcutaneous tissue, and one or more bacterial species may be responsible for the same or different clinical entities. Although classification schemes based on microbial etiology may be the most complete, they offer little to the clinical diagnostic process necessary to expedite appropriate management.1 To place a useful clinicoanatomic classification into perspective, a review of the basic anatomy and microbial ecology of the skin and subcutaneous tissues is necessary.
Basic Anatomy and Microbial Ecology of the Skin and Soft Tissues
The skin consists of an outer layer, the epidermis, and an inner layer, the dermis, which resides on a fibrous connective tissue layer, the superficial fascia. Beneath this layer, the avascular deep fascia overlies and separates muscle groups and acts as a mechanical barrier against the spread of infections from superficial layers to the muscle compartments. Between the superficial and deep fascia lies the fascial cleft, which is mainly composed of adipose tissue and contains the superficial nerves, arteries, veins, and lymphatics that supply the skin and adipose tissue.
Normally, the skin has a resident and a transient flora. The resident flora includes Corynebacterium species, coagulase-negative staphylococci, and Micrococcus species. Staphylococcus aureus is not considered part of the resident flora, but colonization rates of 10% to 30% in the anterior nares, axillae, groins, and perineum are not uncommon. Gram-negative bacilli are not considered part of the normal resident flora, although they are occasionally found in the moist intertriginous areas, such as the toe webs, ...