In a discovery that can help explain how bacteria infect their hosts, American scientists have claimed that a single atom of calcium controls their movement. <br/><br/>Researchers at the University of North Carolina at Chapel Hill have identified a spot on a human pathogen, Pseudomonas aeruginosa, that when blocked, can stop it in its tracks.<br/><br/>The scientists said, "the finding identifies a key step in the process by which bacteria infect their hosts and could one day lead to new drug targets to prevent infection".<br/><br/>"When it comes down to it, a single atom makes all the difference," senior study author Matthew R Redinbo wrote in journal Proceedings of the National Academy of Sciences.<br/><br/>For the last few years, Redinbo and his team has been trying to find out how bacteria's tiny legs or pili function.<br/><br/>They found that these pili act as grappling hooks ‘ the bacteria extend the fibers out, the fibers attach or stick to a surface and then retracted back into the bacteria, pulling it along.<br/><br/>"This crawling movement is called twitching motility, and without it Pseudomonas, a common cause of hospital-acquired pneumonia, would never be able to move from the lung tissue into the bloodstream, where the infection becomes lethal".