90 Efficacy of Topical Antimicrobial Agents Against Bacterial Isolates from Burn Wounds

Abstract Introduction Topical antimicrobials are key to prevention of infection and mortality in the acute burn patient population. The purpose of this study was to determine the effectiveness of commercially available and in-house compounded topical preparations. Methods One hundred isolates from 15 different microorganisms were used to evaluate topical antimicrobial effectiveness. The isolates included 40 Gram-positive and 60 Gram-negative microorganisms. Sixteen multidrug-resistant organisms were included in the study. The study was conducted using the Nathan Topical Well Assay method to assess in-vitro activity. Twenty-two various irrigation solutions and ointments were tested. Since there are no standardized zones to determine susceptibility for topical antimicrobials, any zone of inhibition (>8 mm) was considered to show effectiveness. Results The compounds 1:1:1 + DAB (1 part bacitracin: 1 part silver sulfadiazine: 100,000 units per gram nystatin + 5mg/gram neomycin sulfate + 500 units/gram polymyxin B) and 3:1 + DAB (3 part bacitracin: 1 part silver sulfadiazine + 5mg/gram neomycin sulfate + 500 units/gram polymyxin B) in both irrigation and ointment dosage form demonstrated 100% effectiveness against all isolates. Sodium hypochlorite 0.5% solution appeared to be very effective against gram-negative organisms, but moderately effective against gram-positive organisms. Double antibiotic solution was highly effective against all gram-negative bacteria. 3:1 ointment and 1:1:1 ointment were highly effective against gram-positive organisms and moderately effective against gram-negative organisms. The data indicates that many of the topical antimicrobials target certain bacteria more readily than others. Besides 1:1:1 + DAB and 3:1 + DAB, it shows that more than one drug product is necessary to demonstrate adequate killing ability of a broad spectrum of organisms. Multidrug resistant organisms also indicate more resistance against topical antimicrobials. The only compounds that showed a high degree of effectiveness against MDROs were sodium hypochlorite 0.5% solution, 1:1:1 + DAB ointment and solution, and 3:1 + DAB ointment and solution. Conclusions The bacitracin and silver sulfadiazine component of 3:1 and 1:1:1 has a high degree of effectiveness against Gram-positive organisms. Double antibiotic ointment was moderately effective against Gram-negative organisms. However, when the two were combined into one ointment it created a synergistic effect, whic