By Karen Blum

In the search for new antimicrobial agents to fight superbugs, some researchers have been looking backward, reviving a century-old therapy that hasn’t been used much in decades except in parts of Eastern Europe and the former Soviet Union.

Bacteriophages are naturally occurring viruses that prey on bacteria wherever they are found, including in soil, seawater, the gut and sewage. They can replicate within a target bacterium and blow it up, killing bacterial cells while leaving