An article last week in the journal Lancet Infectious Diseases documented a new and dangerous gene that could allow any bacteria to become a superbug that's resistant to antibiotics and almost impossible to treat. 37 people in the U.K. have been identified as carrying bacteria with the gene, called NDM-1, after visiting India and other parts of Asia for medical tourism. Medical personnel are worried that a new strain of superbug may threaten health worldwide. Why are new bugs so resistant to antibiotics? And what might a world look like as superbugs grow stronger?