[Experimental study of antiinfection effect of topical "moist ointment" in burn wound infection]

A controversy on the therapeutic effect of topical "moist ointment" in burns has been noticed recently. An experimental study is designed for the evaluation of its antibacterial and antiinfection effect. A 20% fullthickness burn wound is produced on SD rat back, and they are seeded with 10(9) CFU of Pseudomonas aeruginosa ATCC-27853. "Moist ointment", cream base, 1% silver sulfadiazine (Ag-SD) cream or 1.2% silver norfloxacin (Ag-FLX) cream is topically applied to the burn wounds at various time interval of 10 min, 8h, 24h, and 48h, after the inoculation of Pseudomonas aeruginosa. Topical therapy lasted for 48h, with dressing change once a day but twice a day for "moist ointment" therapy only. Bacterial counts of subeschar tissue and heart blood culture, and histopathologic study of the wounds are made as laboratory criteria. A modified agar well diffusion (AWD) test is performed as a bacterial inhibitory study using Pseudomonas aeruginosa ATCC-27853, E. coli ATCC-25922, or Staphylococcus aureus ATCC-25923. Results of the study show that Ag-FLX cream has a strong antibacterial effect and Ag-SD cream a moderate effect. However, "moist ointment" and cream base do not show antibacterial effect. Bacterial counts of subeschar tissue and histopathologic study of the infected burn wounds show that more than 70% of the animals in the "moist ointment" group have invasive wound infection, and the incidence of septicemia with Pseudomonas aeruginosa is 50% as determined by blood cultures. The above mentioned results indicate that "moist ointment" has no antibacterial and anti-infection effect.