The subject invention provides a pharmaceutical composition comprising: (i) at least one bacteriophage strain(s) capable of producing a lytic infection in an adherent-invasive Escherichia coli strain; and (ii) a pharmaceutically acceptable carrier; for the treatment of inflammatory bowel disease. The subject invention further provides a method of treating inflammatory bowel disease comprising administering to a subject in need thereof at least one bacteriophage strain capable of producing a lytic infection in an adherent-invasive Escherichia coli strain thereby treating the subject. The subject invention also provides new bacteriophage strains.