Abstract: The present invention provides a composition for treating a bacterial biofilm, comprising a first bacteriophage that is capable of infecting a bacterium within said biofilm, and a first polysaccharide lyase enzyme that is capable of degrading a polysaccharide within said biofilm. The composition preferably further comprises a pharmaceutically-acceptable antimicrobial agent, and may also include a DNase. Also provided are modified bacteriophages, methods of creating modified bacteriophages, use of said compositions and bacteriophage for treating biofilms, and methods for treating biofilms using the bacteriophages and compositions of the invention.