Disclosed herein is an engineered bacteriophage comprising an indicator gene, wherein said indicator gene is an RNA aptamer or a green fluorescent protein (GFP) or GFP-like protein, and further wherein said indicator gene can indicate the presence of a microorganism, such as a bacterial infection. The engineered bacteriophage can be capable of infecting and killing the microorganism. The engineered microorganism can be in a composition for delivery to a subject, and can be in hyaluronic acid, for example. Also disclosed are methods of using the engineered bacteriophage to diagnose and/or treat a subject with a bacterial infection.