Topical chlorhexidine diphosphanilate (WP-973) in burn wound sepsis

We studied the diphosphanilate salt of chlorhexidine (WP-973), as a 2% cream, for therapeutic activity in two rat models of fatal burn wound infection. Control treatments were infection and placebo cream; infection only; infection and 1% sulfadiazine silver; and burning only. Activity against Pseudomonas aeruginosa or Proteus mirabilis was tested in surface-inoculated rats with 20% scalds. Treatments were initiated 24 hours or four hours, respectively, after inoculation. Pseudomonas-infected rats were treated once a day for ten days. Proteus-infected rats were treated once a day for five days. In these experimental models, chlorhexidine diphosphanilate was equal to silver sulfadiazine, an established topical chemotherapeutic agent. In vitro activity was examined using bacteremia isolates from 65 burned patients. Using agar diffusion trench plates, chlorhexidine diphosphanilate was active against all strains. No evidence of cross-resistance between sulfonamide and chlorhexidine diphosphanilate or its components was observed.