Bacteriophages are naturally occurring organisms that kill bacteria. With more and more bacteria becoming immune to antibiotics, scientists are looking at bacteriophages as an alternative way of treating infections. According to this Wired article, "this approach to fighting infection lets nature do the lab work usually carried out at tremendous expense, and with high failure rates, by the pharmaceutical industry. In contrast to engineered drugs, phages are as numerous and varied as the bacteria they attack. What's more, they evolve along with their prey, matching bacterial adaptation step by step."