Efficacy and durability of Bacillus anthracis bacteriophages used against spores

Antibiotics and vaccines help fight anthrax disease, but there are no anthrax spore control methods suitable for use in environments where humans are present. The work reported in this article indicates that bacteriophages may help reduce risk from anthrax spores. Dose-response studies demonstrated that higher concentrations of mixed Bacillus anthracis bacteriophages (3.5 x 10(8) plaque-forming units per milliliter) inhibited subsequent growth of bacteria when sprayed on B. anthracis spores. Phages also were tested for durability under conditions designed to simulate environments possibly encountered during mass phage production, storage, and use against anthrax spores. They remained infectious at temperatures from -20 degrees C to 37 degrees C, under filtration, aerosolization, and treatments with perspiration and blood. Phages were sensitive to temperatures over 55 degrees C and to desiccation. Ultraviolet light reduced spore viability more than phage infectivity under similar conditions. The potential for personal or environmental decontamination of anthrax spores with phages is discussed.