You can't see them, but they are everywhere: dangerous bacteria that could make you sick and even kill.
Ellen Blackwell had Clostridium difficile, or "C. diff," an infection that causes severe diarrhea, fevers, pain and cramping.
"Superbugs" like C. diff are common in hospitals across the country, killing about 100,000 patients each year.
"The organisms are smart. They're always a step ahead of us," said Dr. Sasha Madison, manager of infection control and epidemiology at Stanford Hospital.
But now the Xenex robot aims to outsmart even the toughest strains of bacteria.
First, hospital workers spend about 45 minutes cleaning and disinfecting.
"Following that, we bring this machine in to further disinfect the room," said Brad Igler, Stanford Hospital and Clinics.
The robot uses UV pulsating light to disrupt an organism's DNA, killing spores, bacteria, viruses and mold. It takes about five to 10 minutes per room.
"So what we're trying to do is bring those organisms way, way, way down," said Dr. Madison.
It can be used in patient rooms, the emergency room and even operating rooms. In one study researchers found the robot reduced surface contamination in the O.R. by 81 percent and air contamination by 46 percent.
"We have a higher level of assurance that that room is truly the cleanest it can be for our patients," said Madison.
One hundred hospitals across the country have the disinfecting robots. An average-size hospital with about 120 beds would need two Xenex devices to clean all its rooms. Each device costs about $80,000 and can be bought or leased.