Bacteriophage covalently attached to a carrier particle with an average diameter of from 0.1 microns to 15 microns, are used in topical treatment of bacterial infection. Bacteriophage covalently attached to a carrier particle of average diameter 7 microns or less are used in systemic treatment of bacterial infection. A plurality of bacteriophages lytic against different bacterial strains gives wide antibacterial activity. A combination therapy comprises administration of antibiotic and bacteriophage covalently attached to a carrier particle.
