Bacteriophages, complex viruses that infect bacteria, were first discovered in the early 20th century. Phage therapy soon emerged as a possible treatment for bacterial infections, including epidemic diseases, but this approach was largely abandoned after the advent of antibiotics in the 1940s. More recently, the increasing threat posed by drug-resistant bacteria has led to renewed interest in phage therapy. For what use did the US Food and Drug Administration approve bacteriophages in 2006? Discuss