Methicillin-resistant Staphylococcus aureus (MRSA), a bacterium that causes infection in various parts of the body, is often called a “superbug” thanks to its ability to dodge many common antibiotics. Although most MRSA infections aren’t serious, some can be life-threatening, sometimes resulting in amputation of the infected appendage. Rather than rolling the dice with a multi-drug combination or wasting precious time trying to determine which medicine to prescribe, doctors could soon use a new method for disarming the superbugs: light therapy.