Disclosed are methods of selecting wide host range bacteriophage capable of growing in a plurality of bacteria including pathogenic and non-pathogenic bacteria and bacteriophage selected by the methods. Also disclosed are methods of treating a subject infected with a pathogenic bacterium using bacteriophage and methods of decontaminating objects using bacteriophage. Also disclosed are methods of producing vaccines. In another aspect, methods of determining bacterial viability and methods of improving the sensitivity of a biosensor using wide host range bacteriophages are disclosed.