The present invention is directed to engineered enzymatically active bacteriophages that are both capable of killing the bacteria by lysis and dispersing the bacterial biofilm because they have been also engineered to express biofilm-degrading enzymes, particularly dispersin B (DspB), an enzyme that hydrolyzes β-1,6-N-acetyl-D-glucosamine, a crucial adhesion molecule needed for biofilm formation and integrity in Staphylococcus and E. coli, including E. coli K-12, as well as clinical isolates.