"Contamination of human skin with even a few spores may potentially disseminate disease beyond the initial area of attack," says John Kokai-Kun, a researcher on the study. "There is currently nothing specifically approved for decontaminating human skin of anthrax spores."
Nisin is a natural antimicrobial peptide used as a preservative in heat-processed and low pH foods. It is derived from the controlled fermentation of the naturally occurring milk bacteria Lactococcus lactis. Nisin was awarded the Generally Regarded as Safe (GRAS) designation in the U.S. Federal Register of April, 1988 and is approved as a natural food preservative in the United States. It is also being used in the dairy industry as a topical treatment for mastitis.
Kokai-Kun and his colleagues tested the ability of nisin to neutralize spores of both anthrax and a related microbe, Bacillus cereus. Spores were pre-treated with nisin and then given variety of tests, including their ability to germinate and to cause disease in mice. While untreated spores in a control group were able to germinate and grow in culture and cause lethal infection in mice, the treated spores remained dormant and caused no apparent disease.
The next step for the researchers is to formulate a delivery system. One that appears to have promise is an impregnated wipe. A similar product, with a much lower concentration of nisin than would be necessary against anthrax is already available commercially for treating mastitis in cows. Other options include a topical cream or a foam.
"Given the capacity of nisin to neutralize spores, its common topical use on animals and its GRAS status, we are developing nisin-based formulations for decontamination of human skin exposed to anthrax spores," says Kokai-Kun.