Risk factors for infections in trauma and burn victims
• More common with burns of >30% TBSA
• More common in patients with burns not excised
• May be responsible for conversion of partial thickness burns to full thickness burns
• Suspect if you see black or hemorrhagic focal areas
Bacteria Colonization
Initially (early post-burn) – predominately Gram Positive (GP)organisms
Post burn day 5 – some Gram Negative (GN) organisms
Post burn day 10 – GN organisms predominate
What is the difference between burn wound colonization and burn wound infection? COLONIZATION - The organisms in the wound are not in the unburned tissue INFECTION – Organisms have ‘invaded’ normal tissue
What is burn wound sepsis?
Burn Wound Sepsis = invasive burn wound infection + associated systemic sepsis
How do we make the diagnosis of burn wound infection? Ans. : Burn wound biopsy
• This is a bedside procedure • Scapal excision of elliptical specimen • If anesthesia is used, inject at the periphery of the biopsy site so the sample is not distorted • ½ to the micro lab for culture and organism sensitivity • ½ to the path lab for microscopic evaluation
Histological Staging of the Burn Wound Biopsy Specimen • Stage 1 COLONIZATION 1a: Superficial, microbes on the surface 1b: Penetrating, microbes into the eschar 1c: Proliferating, microbes in the subeschar space • Stage 2 INVASION 2a: Microinvasion, microbes in the viable tissue 2b: Deep invasion, microbes into viable subcutaneous tissue 2c: Microvascular invasion, microbes into the blood vessels or lymphatics
Know how to treat burn wound infection
• Apply a penetrating agent if not already in use (Sulfamylon) • Systemic antibiotics to cover possible organisms until sensitivities are back • Subeschar injection with broad spectrum penicillin drug using a long spinal needle • Excision within the next 12 hours with repeat subeschar injection immediately before excision • WLE of skin and subcutaneous tissue, superficial to the fascia • WLE may include fascia and muscle • Consider biopsy of the bed
Fungi
• COLONIZATION ‘not invasion’ most common is candida confined to the surface or eschar usually
• INVASION most common is asperqillus (more aggressive than candida), less common is phycomycetes, the most aggressive true fungi (this organism crosses fascial planes) Treatment of burn fungal wound infection
• CANDIDA
Colonization – 2x/day topical (clotrimazole) Invasion – Immediate excision, 2x/day topical, systemic (Amphotericin B)
• ASPERGILLOSIS/PHYCOMYCETES
Invasion – Immediate excision, 2x/day topical, systemic (Amphotericin B)
Viral burn wound infection • Rare • MC virus = Herpes Simplex • Oral, Nasolabial • Dx: biopsy or scraping • Tx: topical acyclovir applied q3hrs x 7days • * If hypotension or signs of sepsis suspect systemic herpes, Tx: systemic acyclovir
Cellulitis Evident as erythema (redness) around donor sites or burns. Treat with vancomycin or dicloxacillin
Other Infections in Burn Patients - Think of the following if your patient has a fever and you can’t find a source.
Most common site of infection in a burn patients
• The Lungs Pneumonia • Cause: airborne • When: 1.5 – 2 weeks • Dx: infiltrate plus clinical signs should prompt: 1. Gram stain and culture of endobronchial secretions 2. Antibiotics to cover pending Culture and Sensitivity results
• Suppurative Thrombophlebitis • Any cannulated or previously cannulated vein • Limiting intravenous lines to 3 days reduces incidence of infection • Suspect when hematogenous pneumonia or septicemia without a source • Dx: Clinical, U/S • Tx: Exploration, excision, systemic antibiotics for probable organism
• Endocarditis • 1% incidence in burn patients • Risk - long term infusing catheters • Suspect when positive blood cultures and no source • Dx: Echo • Anatomy: Right-side more common • Organism: Most common = staph aureas • Tx: Max dose antibiotic (systemic) three weeks, check for negative blood cultures
• Suppurative Sinusitis • 1% incidence in burn patients • Risk - long term transnasal intubation, fever without a source • Dx: CT scan • Tx: Broad spectrum antibiotics - surgical drainage may be necessary if unresponsive - consider tracheostomy, gastrostomy
• Bacteremia • 1/5 of blood cultures are positive when obtained during wound manipulation • Antibiotics covering GP and GN are givenduring debridement or excision • Blood cultures are obtained on a scheduled basis • Positive blood cultures are treated
• Urinary Tract Infection • Especially in patients who have had catheters in place for a prolonged period
Infections treatment is guided by the unit's epidemiology.
Risks of Infection
Common microbes