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INTRODUCTION

GUIDING QUESTIONS

  1. Which two bacteria are responsible for the majority of skin infections?

  2. Which skin and soft tissue infections require surgical intervention?

  3. What are the clinical clues that help to differentiate cellulitis from necrotizing fasciitis?

  4. What are the conditions that predispose to necrotizing fasciitis?

  5. Which two organisms most commonly cause myonecrosis?

  6. Which organisms cause indolent soft tissue infections that fail to respond to conventional antibiotic treatment?

  7. Should prophylactic antibiotics be given for bites by humans and animals?

  8. When should tetanus toxoid vaccine and human tetanus immunoglobulin be given?

SKIN AND SOFT TISSUE INFECTIONS

POTENTIAL SEVERITY

Can progress rapidly to shock and death. For deeper soft tissue infections, immediate antibiotic therapy is required, often accompanied by surgical debridement.

CLASSIFICATION OF SKIN AND SOFT TISSUE INFECTIONS

Skin and soft tissue infections are common in every age group. They can infect the young and physically active as well as the elderly and sedentary. It is important for all clinicians to be able to effectively classify these infections to assure that patients promptly receive the appropriate therapy. The symptoms and signs for the different forms of skin and soft tissue infection overlap making an accurate diagnosis challenging.

Two microorganisms are responsible for most cutaneous infections in immunocompetent patients:

  1. Beta-hemolytic streptococcus (groups A, B, C, G, and F). Group G is the most common group in Finland.

  2. Staphylococcus aureus, including community-acquired methicillin-resistant S. aureus (CA-MRSA).

These infections can be classified based on three characteristics. First soft tissue infections should be classified as to whether they are purulent or nonpurulent. As shown in Figure 10-1, purulent infections include folliculitis, furunculosis, and skin abscesses and nonpurulent infections include erysipelas, cellulitis, and necrotizing fasciitis.

Figure 10-1

Classification of skin and soft tissue infections by the presence or absence of purulence.

Second they should be classified with regards to the depth of the infection (see Figure 10-2). The more superficial infections include impetigo, erysipelas, and folliculitis. As these infections penetrate deeper, they may become furunculosis (associated with hair follicles), hidradenitis (associated with sweat glands), and skin abscesses. Most of the superficial localized infections (impetigo, folliculitis, furuncles) are caused by S. aureus or beta-hemolytic streptococci. These infections rarely require hospitalization and often respond to local measures. Recurrence may be prevented by reducing specific microbial carriage.

Figure 10-2

Schematic of the anatomic sites of soft tissue infection. (Adapted with permission from Saurat JH, Grosshans E, Laugier P, Lachapelle JM, eds. Dermatologie et vénéréologie. 2nd ed. Paris, France: Editions Masson; 1990:109.)

Third these infections should be classified based on the severity of illness. Once skin and soft tissue infections spread through ...

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