Burn Wound Infections Clinical Presentation

The American Burn Association (ABA) recently published criteria for sepsis and wound infections. Regular monitoring of burn wounds allows for the early recognition of infection. Local signs of burn wound infection include conversion of a partial-thickness injury to full-thickness wound, worsening cellulitis of surrounding normal tissue, eschar separation, and tissue necrosis.

According to the ABA, the various types of burn wound infections include wound colonization, wound infection, invasive infection, cellulitis, and necrotizing infection/fasciitis.

• Wound colonization is characterized by the presence of low concentrations of bacteria on the surface without invasion or systemic signs or symptoms of infection. Tissue biopsies obtained from colonized but not infected skin usually reveal less than 10⁵ bacteria per gram of tissue.
• Wound infection is associated with higher concentration of bacteria (>10⁵ bacteria per gram of tissue) within the wound or wound eschar but not a deeply invasive infection.
• An invasive infection includes concentrations of bacteria (frequently >10⁵ bacteria per gram of tissue) at an appropriate depth of the burn wound to cause suppurative separation of the eschar or graft loss with involvement of unburned tissue or the presence of a systemic response consistent with sepsis.
• Cellulitis manifests as erythema, induration, warmth, and tenderness in the tissue surrounding the burn wound or wound eschar and occasionally the presence of sepsis. Erythema alone may not indicate cellulitis.
• Necrotizing infection/fasciitis involves an aggressive invasive infection with involvement of structures below the skin.

• Wound infection

  • Suppurative separation of the eschar
  • Graft loss with involvement of unburned tissue or the presence of a systemic response consistent with sepsis
  • Change in wound color (focal areas of red, brown, or black)
  • Green discoloration of the subcutaneous fat
• Cellulitis

  • Erythema (Erythema alone may not require treatment.)
  • Induration
  • Warmth
  • Tenderness
  • Sepsis (occasionally)
• Necrotizing infection/fasciitis - Aggressive invasive infection with involvement of structures below the skin (eg, muscle, bone, organs)
• Signs of sepsis

  • Temperature greater than 39^o C or less than 36.5^o C
  • Progressive tachycardia (>110 beats per minute)
  • Progressive tachypnea
    • More than 25 breaths per minute without assisted ventilation
    • Minute ventilation greater than 12 L per minute min if intubated and mechanically ventilated
  • Thrombocytopenia (< 100,000/μL; does not apply immediately after initial resuscitation)
  • Hyperglycemia (in the absence of pre-existing diabetes mellitus)
    • Plasma glucose levels greater than 200 mg/dL in the absence of treatment
    • Significant resistance to insulin (>25% increase in insulin requirement)^[2]
  • Inability to continue enteral feedings for more than 24 hours
    • Abdominal distension
    • High gastric residuals
    • Uncontrollable diarrhea

• Risk factors for the development of a burn wound infection

  • Extremes of age
  • Comorbidities such as obesity and diabetes
  • Immunosuppression (eg, due to AIDS)
  • Invasive devices (eg, catheters)
  • Burns involving greater than 30% TBSA
  • Full-thickness burns
  • Failure to cover burns or failed skin graft resulting in prolonged open burn wounds
  • Improper early burn care
• Organisms frequently causing invasive burn wound infection

  • Gram-positive bacteria
    • S aureus, including MRSA
    • Coagulase-negative S taphylococcus species
    • Enterococcus species, including vancomycin-resistant species
  • Gram-negative bacteria
    • P aeruginosa
    • Klebsiella species
    • Acinetobacter species
    • Escherichia coli
    • Serratia marcescens
    • Enterobacter species
    • Proteus species
  • Fungi (Burn wounds complicated by fungal infections constitute an independent predictor for mortality in patients with a burned TBSA of 30-60%.^[3] )
    • Candida species
    • Aspergillus species
    • Fusarium species
    • Phaeohyphomycetes (dark molds)
    • Zygomycetes (eg, Rhizopus, Mucor, Absidia)
  • Viruses (Cutaneous disease typically occurs in healing partial-thickness burns and donor sites.)
    • Herpes simplex virus
    • Varicella-zoster virus