Topic One: Antimicrobials

There are a range of antimicrobial agents that can be utilised for the treatment of infection in burn injuries. The most used topical antimicrobial in burn wounds is silver sulfadiazine (SSD) cream. This is a broad-spectrum agent; it can be applied as a 1cm thick layer and needs to be washed off and redressed daily. However, it is worth noting that SSD cream may itself delay healing due to a potential toxic effect. A Cochrane review of dressings for superficial and partial-thickness burns revealed that silver sulphadiazine was associated with lower healing outcomes than biosynthetic, silicone-coated, and silver dressings. (Wasiak et al., 2013)

Other forms of silver, particularly elemental silver or in the ionic state (Ag+), have been demonstrated to have a broad antimicrobial effect and may have some benefit over SSD dressings in terms of healing time. (International Best Practice Guidelines, 2014; Jeschke et al., 2018)

Common topical antimicrobials used in burn management:

Agent	Description
Silver dressings	Silver-containing calcium alginates, foams, gels, gelling fibres and non-adherent synthetic contact layers Some formulations kill bacteria within the dressing, other release silver into the wound bed itself Broad spectrum coverage May potentially be toxic in high concentrations and use, to fibroblasts and keratinocytes or if not delivered in a sustained-release manner May require less frequent dressing changes (except for the silver gel)
Honey	Medical grade leptospermum honey-containing dressings such as calcium alginates, gels and pastes Biocidal effect is multifactorial Broad spectrum coverage Low toxicity May require less frequent dressing changes (except for the gel and paste)
PMHB	Polyhexamethylene biguanide (PHMB)-containing dressings such as cleansing solution, gauze squares, transfer foam, foam, gel and non-adherent synthetic contact layer Bacteria kill occurs largely in/on the dressing Broad spectrum coverage Low toxicity May require less frequent dressing changes (except for the PMHB gel)
Gentian Violet / Methylene Blue	Gentian violet – and methylene blue-containing polyvinyl alcohol or polyurethane foam Biocidal effect is multifactorial Broad spectrum coverage Non-cytotoxic May require less frequent dressing changes
PVP-I	Knitted viscose fabric impregnated with polyethylene glycose containing 1% povidone iodine Biocidal Broad spectrum coverage May require less frequent dressing changes Used specifically for prevention of infection in minor burns
Silver sulfadiazine (SSD) cream	Water-soluble cream containing 1% silver sulfadiazine Bacteriostatic Broad spectrum, but lacks fungal and vancomycin-resistant enterococci activity Has cytotoxic effects on fibroblasts and keratinocytes and may delay healing of superficial burns May create a pseudo eschar Requires frequent applications (more than once daily) Avoid in patients with sulfonamide allergies (sulfa)

Adapted from (Jeschke et al., 2018)