Comparison of standard and chlorhexidine-derivative topical antibacterial agents on the infected burned rat wound.

The effect of daily treatment with three current topical antibacterial agents and four experimental formulations of chlorhexidine was evaluated after 1 week in rats with full thickness burns. The burn was seeded with 1 x 10(8) colony forming units (CFU) of a strain of P. aeruginosa isolated from the infected wound of a burn patient. Mafenide acetate resulted in the lowest incidence of muscle invasion and yielded the lowest mean eschar and muscle concentrations. Mafenide acetate, gentamicin, and chlorhexidine diphosphanilate (0.5 per cent) had lower mean eschar and muscle concentrations than silver sulphadiazine 1 per cent alone. Addition of chlorhexidine digluconate (0.5 per cent or 1.0 per cent) to silver sulphadiazine reduced mean eschar concentrations but not muscle concentrations compared to silver sulphadiazine alone. All treatments effectively suppressed systemic invasion of lung and blood and prevented death compared with controls. Mafenide acetate, gentamicin sulphate and chlorhexidine disphosphanilate 0.5 per cent were most effective against this patient strain of P. aeruginosa.