bacteriophages: obscure past, promising future.

is a Gram-positive, spore-forming bacterium that is the causative agent of American foulbrood (AFB), the most devastating bacterial disease of the honeybee. is antibiotic resistant, complicating treatment efforts. Bacteriophages that target are rapidly emerging as a promising treatment. The first phages were isolated in the 1950s, but as was not antibiotic resistant at the time, interest in them remained scant. Interest in phages has grown rapidly since the first phage genome was sequenced in 2013. Since then, the number of sequenced phage genomes has reached 48 and is set to grow further. All sequenced phages encode a conserved -acetylmuramoyl-l-alanine amidase that is responsible for cleaving the peptidoglycan cell wall of . All phages also encode either an integrase, excisionase or Cro/CI, indicating that they are temperate. In the last few years, several studies have been published on using phages and the phage amidase as treatments for AFB. Studies were conducted on infected larvae and also on hives in the field. The phages have a prophylactic effect, preventing infection, and also a curative effect, helping resolve infection. phages have a narrow range, lysing only , and are unable to lyse even related species. phages thus appear to be safe to use and effective as treatment for AFB, and interest in them in the coming years will continue to grow.