What labs and medications should be ordered in the Emergency Department (ED) to evaluate and manage suspected burn infections?

Evaluation of Suspected Burn Infections in the Emergency Department

For suspected burn infections in the ED, obtain blood cultures and quantitative wound cultures (either tissue biopsy from the advancing margin or quantitative surface swabs), ensuring the wound is thoroughly cleansed and free of topical antimicrobials before sampling. 1

Diagnostic Testing

Wound Cultures

• Tissue biopsy is the gold standard specimen - obtain from the advancing margin of the lesion after thorough cleansing and removal of topical antimicrobials 1
• Quantitative culture is essential - request specifically, as not all laboratories offer this service 1
• If tissue biopsy is not feasible, quantitative surface swabs are acceptable but have significant limitations (reflect surface flora rather than deep tissue invasion) 1
• Twice-weekly sampling of the same site is recommended when using surface swabs to monitor bacterial colonization trends 1
• Histopathological examination should supplement quantitative tissue cultures to better assess the extent of microbial invasion 1

Blood Cultures

• Always obtain blood cultures to detect systemic disease secondary to the burn wound 1
• Blood cultures are critical for identifying burn sepsis, which remains the leading cause of death in severely burned patients 2, 3

Critical Pre-Sampling Requirements

• Thoroughly cleanse the wound before obtaining any specimen 1
• Remove all topical antimicrobials and debris that can affect culture results 1
• Avoid surface swabs alone - they are inadequate and do not represent the disease process 1

Common Pitfalls to Avoid

• Do not label specimens as "wound" alone - be specific about body site and type (e.g., "thermal burn, right forearm") 1
• Do not request "report everything that grows" - this leads to confusion between colonization and true infection 1
• Do not rely on clinical signs alone - diagnosis of burn wound infections is challenging and unreliable without microbiological confirmation 1
• Recognize that quantitative cultures may not be available at all facilities - confirm laboratory capabilities or arrange transfer to a reference laboratory 1

Expected Pathogens

• Early colonization (first week): Gram-positive bacteria from endogenous skin flora (Staphylococcus aureus, including MRSA) 1
• Later colonization (after one week): Gram-negative bacteria, particularly Pseudomonas aeruginosa and Acinetobacter species 1
• Burn wound infections are typically polymicrobial involving both Gram-positive and Gram-negative organisms 1
• Fungal infections (Candida, Aspergillus, Fusarium) can occur, particularly in severely burned patients 4

Topical Antimicrobial Considerations

While not diagnostic tests, understanding current topical therapy is important:

• Silver sulfadiazine is commonly used but has been associated with increased burn wound infections and longer hospital stays compared to dressings/skin substitutes 1
• Mafenide acetate inhibits carbonic anhydrase and may cause metabolic acidosis, requiring monitoring of acid-base balance 5

Laboratory Coordination

• Confirm your laboratory offers quantitative cultures before specimen collection 1
• For patients requiring grafting, quantitative biopsy cultures are particularly important 1
• If services are unavailable locally, arrange specimen transfer to a qualified reference laboratory (expect longer turnaround times) 1