Topical bactroban (Mupirocin): Efficacy in treating burn wounds infected with methicillin-resistant staphylococci

Bacterial antimicrobial susceptibility predictors such as the minimal inhibitory concentration (MlC) assay and Nathans Agar Well Diffusion (NAWD) assay provide essential information relevant to the therapeutic approach in burn-wound sepsis. The susceptibilities of 68 gram-positive burn-wound isolates were tested against topical Bactroban (mupirocin) (Beecham Laboratories, Bristol, Tenn.) and compared with other topical antimicrobials such as mafenide acetate, silver sulfadiazine, and bacitracin/neomycin/polymyxin (BNP). Topical susceptibility data were obtained with a modification of NAWD assay. Bactroban’s antimicrobial activity was greater than that of mafenide acetate (100% vs 97%), and significantly greater than that of silver sulfadiazine and that of BNP (p < 0.001). Of the 68 isolates that were susceptible to Bactroban, 51 were predominately methicillin-resistant staphylococci (MRSA). Bactroban showed in vitro activity against 71% of the 85 gram-negative isolates tested. Mafenide acetate showed activity against 89% of these isolates, a significant difference compared with Bactroban (p < 0.02). In general, no significant difference was found between the activities of Bactroban and silver sulfadiazine against the gram-negative isolates. The activities of mafenide acetate and silver sulfadiazine against isolates of Psendomonas aertiginosa were significantly greater than that of Bactroban (p < 0.05). Bactroban may be used in the treatment of documented staphylococcal burn-wound infections. On the basis of the in vitro data, 13 patients with MRSA burn-wound infections susceptible to Bactroban were evaluated. Quantitative wound biopsies were employed to determine the efficacy of this therapeutic approach. The outcome of these infections was correctly predicted by the NAWD assay in 92.3% of the patients treated (p < 0.0005). The period of treatment ranged from 2 to 17 days. On the basis of these data MRSA burn-wound infections can be successfully treated with Bactroban as determined by the NAWD susceptibility assay.