Some bacteria have grown so strong that they cannot be killed with antibiotic drugs. Medical experts call them antibiotic-resistant bacteria. The World Health Organization says antibiotic-resistant bacteria are one of the biggest threats to human health. But, researchers now say they may have found a way to fight them. A team of researchers from three universities is working on a cell-killing “machine” that is too small for the human eye to see. “We want to be bacteria’s worst nightmare.” That was James Tour, a member of the team. Tour is a chemistry professor at Rice University in Houston. He is also a professor of materials science and nanoengineering and computer science. In addition to Rice University, the researchers come from Durham University in Britain and North Carolina State University. The team is experimenting with very small nanomachines that can drill into a cell and kill it.