Hospitals are dangerous places. About 2 million patients a year acquire new infections in them, according to the U.S. Centers for Disease Control and Prevention. A major cause is bacterial contamination of urinary catheters, breathing tubes and implants-a situation made more difficult by the fact that some bacteria form tough antibiotic-resistant films on such devices. University of Texas Health Science Center biomaterials researcher H. Ralph Rawls is developing a nontoxic polymer coating that slowly dissolves in bodily fluids. The coating could be applied to almost any object doctors put into the body. As the polymer dissolves layer by layer, it frees surface-attaching bacteria; this process prevents the formation of a bacterial film and makes the germs susceptible to therapeutic drugs and the immune system. The longer the expected contact between the instrument and the body, the thicker the polymer coating. This summer, Rawls plans to add another function to the polymer by incorporating drugs that encourage tissue repair; he hopes the material will be available clinically in three to five years.