Infectious Complications

Epidemiology

• Overall burn mortality ~5.3%• Age and TBSA (0.7% if TBSA <10%, 78% if TBSA 90%).• 14% Palliation• 27% MOF, 12% Burn shock, 12% Trauma, 11% Respiratory

failure• 4% sepsis burn wound

• Complications• 31% respiratory (pneumonia / ARDS)• 17% cellulitis and wound infection• 15% septicaemia and other infections

• MRSA first entered Australia through the Perth burns unit• R-Acinetobacter appeared in Concord and Perth immediately after Bali

Wound infection: Risk factors

• Extreme age• Prolonged inpatient stay• Large burns (>30% TBSA)• Full thickness burns• Improper initial burn care and failure to cover burnt area

Pathophysiology

• Breach in the immune barrier

• Skin (innate)• Avascular areas (role of debridement)• Depressed T-cell activity, decreased level of complement and cytokines,

reduced capacity of Neutrophils

Pathophysiology

• Rapid colonization by bacteria (S. aureus, Pseudomonas, Acinetobacter)• Organism present on the wound• GI tract (Gram negatives, Candida)• Hospital environment

• Biofilm after 7 days• Colonization harder to eradicate (role of early debridement)

• Fungal infection usually delayed• Anaerobes are rare (except electrical injuries)

Other infections

• Deep infections in deep burns / compartments

• Critical illness• Lines. Including infected DVT.• VAP.• Gut (compartment syndrome, Clostridium difficile).

Prevention

• Early debridement and escarrectomy• Early cover (skin graft)• Wound care

• Dressing: silver dressing• High Absorbing capacity (exsudate)• Antiseptics: Chlorhexidine, Soap, Betadine

• Immune preservation: feeding, pro-biotics

Prevention: Cochrane review

• Topical Antibacterials (decrease bacterial load)• Silver dressings: Acticoat, Aquacel Ag, Mepilex• Silver Suphadiazine

• Increased risk of infection?• Topical Antibiotics (Bacitracin, Neomycin, Polymyxin B)

• No benefit

• Systemic Antibiotics• No impact on burn infection rate

Prevention: Cochrane review

• SDD?

• No significant effect on all types of infections• Increased rate of MRSA• Burns is exclusion criteria in SuDDICU

• Rectal tubes / Zassi

Prevention

• Infection control measures

• Hand hygiene• Ante rooms. Pressurized rooms. 100%

exhaust air conditioning.• UV irradiated water. Micron filtering.• Burns unit. Dedicated burns theatre.• Staff training

Classification• Colonization

• Surface. No invasion, no systemic sign• Biopsy: usually <10e5 bacteria per gram

• Wound infection (threat to the wound, not the patient)• Wound / eschar infection without deep invasion• Biopsy: >10e5 per gram

• Invasive infection• Deeper infection, with involvement of non burned tissue and systemic response• Suppurative separation of eschar and graft loss

• Cellulitis• Inflammed tissue surrounding the burned area (not necessarily infective)

• Fasciitis / necrotizing infections• Aggressive infection of structures below the skin

Clinical signs

• Systemic response.• Sepsis is a diagnostic challenge

• Change in wound colour. Green discoloration of subcutaneous fat.

• Suppurative separation of the eschar. Graft loss with involvement of unburnt tissue

• Cellulitis

Pathogens

• S. aureus (MSSA / MRSA), Klebsiella:• Early infections

• Hospital GNR (Pseudomonas, Acinetobacter):

• Later (> 2weeks)

• Fungus: Candida, Aspegillus, Molds (Fusarium, Mucor, Rhizopus, …)

Pathogens

Diagnosis

• Differentiating SIRS from Sepsis is particularly challenging in burns patients

• PCT?

• Examination

• Culture data:• Quantitative swab / quantitative biopsy:

limited value• Histopathology: assess depth of

infection

Treatment

• Pseudomonas• Acetic Acid

• Secondary dressing• Wick exsudate from primary dressing• Exudry, Mesorb, Zetuvit, Combine

Treatment

• Systemic Antibiotics

• Adjusted dose• High VD• Augmented Renal Clearance (ARC)

• CrCl > 130 mL/min • Driven by response to infection (high CO) and treatment interventions (fluids,

vasopressors)• 82% patients will not achieve therapeutic levels with standard doses

Treatment

• Systemic Antibiotics

• Appropriate spectrum• Culture results• Pseudomonas, Acinetobacter• Piperacillin, Ticarcillin, Aminoglycosides, Carbapenems, Ceftazidim

• Multiresistant organisms• MRSA: Vancomycin, Linezolid, Daptomycin, Ceftarolin• MRAB, MRPA: Colistin, Amikacin, High dose Meropenem. Newer agents?