Burn wound infection

Overview

Burn wound infection is the leading cause of morbidity and mortality in patients who survive the initial burn resuscitation. The loss of the skin barrier, combined with burn-induced immunosuppression, creates an environment where microbial colonization is inevitable and progression to invasive infection is a constant threat. Early recognition of invasive infection and targeted intervention with surgical and antimicrobial strategies are core competencies in burn care.

Pathophysiology and classification

The definitive review of burn wound infection pathophysiology and management was provided by Pruitt et al. ^[1], who established the classification system for burn wound infections based on causative organism, depth of invasion, and tissue response. They demonstrated that time-related changes in wound flora follow a predictable pattern from gram-positive to gram-negative predominance, recapitulating the history of burn wound infection itself. Critically, Pruitt et al. established that quantitative cultures of biopsy samples can identify predominant organisms but are not sufficient to diagnose invasive infection -- only histologic examination of wound biopsies reliably differentiates colonization from invasion by allowing staging of the invasive process. The combination of effective topical antimicrobial chemotherapy and early burn wound excision has significantly reduced the overall incidence of invasive wound infections, though patients with extensive burns in whom wound closure is difficult to achieve remain at risk.

Church et al. ^[2] provided a comprehensive review of burn wound infection classifications, diagnosis, treatment, and prevention. They confirmed that early excision of the eschar has substantially decreased the incidence of invasive burn wound infection and secondary sepsis, but most deaths in severely burned patients are still attributable to burn wound sepsis or inhalation injury complications. They also highlighted the potential of silver-impregnated devices (central lines, Foley catheters) to reduce nosocomial infections from prolonged device placement.

Assessment and diagnosis

Loebl et al. ^[5] established the method of quantitative burn wound biopsy cultures and its routine clinical application, providing the technical foundation for the greater than 10^5 organisms per gram threshold that has been widely adopted as a marker of wound infection risk. This technique, while imperfect as a standalone diagnostic, remains a valuable adjunct to clinical assessment and histopathology.

Prevention

Environmental and infection control

Palmieri ^[3] addressed how burn unit structure and design impact infection rates, emphasizing that because many factors promoting wound healing also promote infection, unit design must prioritize containment, segregation, environmental controls, and dedicated facilities. Particular attention to ventilation, temperature control, surface cleaning, and patient movement pathways is essential for minimizing cross-contamination.

The practical challenge of infection control was studied by Lee et al. ^[4], who conducted four consecutive 2-month surveillance periods in a burn ICU. Initial unit-acquired colonization was 63% with a 51% error rate in isolation technique. A mandatory education session alone failed to reduce colonization. However, implementing a simplified isolation technique decreased unit-acquired colonization from 63% to 33% and significantly delayed Pseudomonas aeruginosa colonization from 7.8 to 21 days (P < 0.05), while simultaneously reducing isolation costs from $53,000 to $30,000 over 6 months.

Topical antimicrobial prophylaxis

The bacteriological basis for topical prophylaxis was demonstrated in the foundational silver nitrate studies by Brentano et al. ^[6] and the introduction of silver sulfadiazine by Stanford et al. ^[7], which together established topical antimicrobials as the cornerstone of burn wound infection prevention. These agents shifted the dominant wound flora and reduced invasive infection rates substantially.

Management

Bacterial infections

The challenge of multidrug-resistant organisms in burn units was quantified by Neely et al. ^[8], whose multicenter study found that while 80% of MDROs remained susceptible to topical agents, susceptibility was significantly reduced compared to non-MDROs (P < 0.05). Zones of inhibition were smaller for MDROs across most agents (P < 0.002), and neomycin showed the most dramatic loss of efficacy (26% vs. 74% susceptibility, P < 0.01). These findings underscore the importance of local surveillance and tailored topical agent selection.

For MRSA wound infections specifically, Strock et al. ^[9] demonstrated that topical mupirocin achieved 100% in vitro activity against gram-positive isolates including MRSA, with clinical outcomes correctly predicted by susceptibility testing in 92.3% of treated patients. This targeted approach is valuable when culture data identify MRSA as the dominant pathogen.

Fungal infections

Fungal infections represent an increasingly recognized threat in severely burned patients. Barret et al. ^[10] reported successful treatment of angioinvasive fungal infections with high-concentration topical nystatin powder (6,000,000 units/g) in four consecutive patients where systemic antifungals had failed. Dudoignon et al. ^[11] conducted a 10-year retrospective cohort study of 276 patients with 15% or greater TBSA burns and found that 33.7% had at least one positive fungal diagnostic criterion. Mortality increased with the number of positive criteria: 12.7% with zero positive criteria versus 46.7% with five or more (P < 0.001). The coexistence of multiple mold species was particularly ominous. The combination of skin biopsy (direct examination and culture) with species-specific plasma quantitative PCR enhanced timely diagnosis and should guide broad antifungal coverage decisions.

Viral infections

Viral wound infections, while less common, can be rapidly progressive. Sheridan et al. ^[12] reported six patients (four adults, two children) who developed severe herpetic ulceration during the immunosuppressed state of burn recovery. All cases responded to prompt systemic and topical acyclovir treatment without residual scarring, emphasizing that rapidly progressive vesicles and ulceration in burn patients warrant immediate evaluation for herpes simplex virus.

Controversies and Evidence Gaps

The definition of burn wound infection itself remains controversial. The distinction between colonization (inevitable in open wounds) and true invasive infection (requiring intervention) depends on histologic examination, which is invasive, requires pathology expertise, and has sampling error. Whether quantitative cultures alone can reliably guide treatment decisions -- or whether they merely complement clinical judgment and biopsy -- continues to be debated.

Prophylactic systemic antibiotics for burn patients remain contentious. Current evidence generally does not support routine prophylaxis, but perioperative antibiotic use around excision and grafting is common practice without strong randomized trial support. The optimal duration and spectrum of perioperative coverage are poorly defined.

The rising prevalence of MDROs in burn units, documented by Neely et al. ^[8], challenges both topical and systemic treatment assumptions. Whether topical agent cycling or rotation can slow resistance emergence has not been tested in prospective trials. Local antibiogram data are essential but not universally maintained for topical agents.

Fungal infections are likely underdiagnosed, as Dudoignon et al. ^[11] demonstrated that one-third of severely burned patients had positive fungal criteria. Standardized case definitions for invasive mold infections in burns do not yet exist, making both clinical decision-making and research challenging.

References

[1] Pruitt BA et al. (1998). Burn wound infections: current status. PMID: 9451928 [2] Church D et al. (2006). Burn wound infections. PMID: 16614255 [3] Palmieri TL (2019). Infection Prevention: Unique Aspects of Burn Units. PMID: 30676249 [4] Lee JJ et al. (1990). Infection control in a burn center. PMID: 2286616 [5] Loebl EC et al. (1974). The method of quantitative burn-wound biopsy cultures and its routine use in the care of the burned patient. PMID: 4588085 [6] Brentano L et al. (1966). Bacteriology of large human burns treated with silver nitrate. PMID: 5330066 [7] Stanford W et al. (1969). Clinical experience with silver sulfadiazine, a new topical agent for control of pseudomonas infections in burns. PMID: 5771755 [8] Neely AN et al. (2009). Are topical antimicrobials effective against bacteria that are highly resistant to systemic antibiotics? PMID: 19060725 [9] Strock LL et al. (1990). Topical Bactroban (mupirocin): efficacy in treating burn wounds infected with methicillin-resistant staphylococci. PMID: 2123203 [10] Barret JP et al. (1999). Topical nystatin powder in severe burns: a new treatment for angioinvasive fungal infections refractory to other topical and systemic agents. PMID: 10498358 [11] Dudoignon E et al. (2026). Characteristics of mycological criteria for the diagnosis of invasive mold infections in patients with severe burn injury. PMID: 41641958 [12] Sheridan RL et al. (2000). Cutaneous herpetic infections complicating burns. PMID: 10925184