What is the most common source of infection in burn patients?

Most Common Source of Infection in Burn Patients

The burn wound itself is the most common source of infection in burn patients (option a). 1 Burn wounds provide an ideal environment for microbial colonization and invasion due to the disruption of the skin barrier and subsequent immunosuppression.

Pathophysiology and Microbiology of Burn Wound Infections

Burn wounds become rapidly colonized following injury:

• Initially by Gram-positive bacteria from the patient's endogenous skin flora
• Within a week, Gram-negative bacteria typically become predominant 1
• Infections are usually polymicrobial in nature

The damage to the skin barrier following burns disrupts the innate immune system, significantly increasing susceptibility to bacterial infection. While burn wound surfaces are sterile immediately following thermal injury, they quickly become colonized with microorganisms 1.

Diagnosis of Burn Wound Infections

Accurate diagnosis of burn wound infections requires:

• Sampling of the burn wound by either surface swab or tissue biopsy 1
• Quantitative culture is recommended for monitoring the presence and extent of infection
• Tissue biopsy is superior to surface swabs as it reflects the actual invasive infection rather than surface colonization
• Histopathological examination should supplement quantitative bacterial culture to better assess microbial invasion 1

Other Sources of Infection in Burn Patients

While the burn wound is the primary source of infection, other sites can become infected:

1. Pneumonia - The second most common infection in burn patients, particularly in those with inhalation injuries 2
2. Urinary tract infections - Often associated with indwelling catheters
3. Bloodstream infections - Can occur secondary to wound infections
4. Device-related infections - Associated with central venous catheters and other invasive devices

Management Principles

Key aspects of preventing and managing burn wound infections include:

• Early excision of necrotic tissue (eschar) to substantially decrease the incidence of invasive burn wound infection 1, 3
• Topical antimicrobial therapy to reduce bacterial colonization
• Systemic antibiotics when invasive infection is present
• Regular wound surveillance with quantitative cultures 4
• Strict infection control measures to prevent cross-contamination

Common Pathogens

The most common pathogens in burn wound infections include:

• Staphylococcus aureus (including MRSA)
• Pseudomonas aeruginosa
• Acinetobacter species
• Enterococcus species (including VRE)
• Fungal pathogens (Candida, Aspergillus, and Fusarium species) in later stages 5

Risk Factors for Infection

Factors that increase the risk of infection in burn patients include:

• Extent of burn (total body surface area affected)
• Depth of burn
• Presence of inhalation injury
• Delayed excision of burn wounds
• Use of invasive devices
• Patient factors (age, comorbidities, immunosuppression) 6, 3

The mortality risk increases significantly when burn size exceeds 40% of total body surface area 3.