Effects of Commonly Used Topical Antimicrobial Agents onAcinetobacter baumannii: An In Vitro Study

Acinetobacter baumannii has recently emerged as an important pathogen among wounded soldiers in Iraq. Because of its ability to develop resistance to antimicrobial agents, wound infections with A. baumannii are difficult to treat and can lead to septicemia and even death. Use of appropriate topical antimicrobial agents in these circumstances could be one of the first steps in the prevention of A. baumannii wound infections. In this study, we present the in vitro effects of seven common topical antimicrobial creams and dressings on A. baumannii. A. baumannii was subjected to sensitivity tests with mupirocin, silver sulfadiazine, mafenide acetate, a double-antibiotic combination of polymyxin and bacitracin, a triple-antibiotic combination of neomycin, bacitracin, and polymyxin, and two silver-containing dressings. Zones of inhibition were measured after 24 hours of incubation. Of the evaluated antimicrobial agents, mafenide acetate was the most efficacious, followed by mupirocin and triple- and double-antibiotic combinations (in decreasing order). The silver-containing dressings yielded smaller zones of inhibition, compared to the previously mentioned agents, and no zone of inhibition was observed with silver sulfadiazine. Further in vivo studies on the effects of antimicrobial agents against A. baumannii are necessary to substantiate these findings and to determine the potential clinical relevance of these therapies.