. >> reporter: colleen costello's life like so many big things had a humble beginning in a small house just off the campus of rensselaer in troy, new york. >> they started to work in the kitchen and get small electrical fires and things like that. >> reporter: 18 months later, just this fall her company vital vio began selling like the kill germs. more specifically, they kill bacteria. >> there's some initial skepticism. it's a white light you can replace in your ceiling and safe. it's never been seen before. >> reporter: who knows when it might have been seen? if colleen's grandmother hadn't gone into a hospital and wound up with a dangerous infection, mrsa, it's resistant to antibiotics. >> the room needed to be closed down. she had to stay there for significantly more length of time, more doses of medicine to be received. >> reporter: her grandmother is fine now but since, costello is how to reduce the cost of hospital acquired infections. $30 billion to $40 billion in the u.s. when she took entrepreneur ship class, the light was turned on. >> this is a large problem for us all. >>