Innovator | Mark Stibich

A Robot for Zapping Supergerms

Caroline Winter


When Mark Stibich walked into the boardroom of a Florida hospital last June, he was greeted with the Star Wars theme song. The hospital was celebrating its deployment of Stibich’s germ-busting robot, which bears a slight resemblance to R2-D2. The wheeled device emits a pulsing ultra-violet light that disinfects rooms by zapping viruses and bacteria.

Hospital-acquired infections, some caused by superbugs that have become resistant to traditional cleaning chemicals, are a leading cause of death in the U.S., killing roughly 100,000 Americans a year. A 2008 study published by the Society for Healthcare Epidemiology of America found that fewer than 50 percent of surfaces get cleaned after a patient leaves a hospital room. Some drug-resistant bugs can live up to six months, lurking in corners and crevices. While most hospital-acquired infections were once treatable, today there’s often no cure.

Stibich, a 40-year-old epidemiologist who got his Ph.D. from Johns Hopkins, began contemplating hospital hygiene in 2008 while working in Russia with his wife on an HIV prevention and treatment grant from the UN Global Fund. Room disinfection methods generally take at least an hour and often involve toxic gases. Stibich knew that ultra-violet light is used to disinfect medical equipment, and even food. The idea of using it to sanitize rooms hit him after he heard that a “pulsed xenon UV lamp” was being used to kill airborne tuberculosis germs in Russia.

Stibich co-founded Xenex Healthcare Services with his wife in 2009, naming the Texas-based company after the xenon gas used to produce UV light. He’s raised more than $20 million, some from Morris Miller, now Xenex’s chief executive officer, who co-founded the cloud computing company Rackspace Hosting. Hospital housekeepers wheel in the trash-can-size robot, close the door, and use a remote to turn it on. UV light flashes for 5 to 10 minutes from the device’s movable “head,” killing viruses, bacteria, and spores by destroying their DNA.

The University of Texas MD Anderson Cancer Center, the first hospital to try Xenex’s robot, found that it cut bacterial contamination by a factor of 20 and killed 95 percent of the deadly pathogen C. difficile. Studies at other hospitals found C. diff reduction rates of 75 percent. Cooley Dickinson Hospital in Northampton, Mass., uses three rental Xenex robots and says it’s seen C. diff infections fall 53 percent. That adds up to significant savings, as each infection costs an average $30,000, says Joanne Levin, medical director of the hospital’s infection prevention program.

More than 100 hospitals now use the robots. Most buy or rent them in pairs. The cost per robot is $125,000, or a monthly fee of $3,700. Many are given names like Violet and Ray. Stibich hopes hospitals keep them in constant use — and not only in patient quarters. Says Stibich, “We have one customer who uses it routinely in the staff locker rooms to get rid of the foot odor.”

Education Went to Yale and served in Mongolia with the Peace Corps

How it works Creates UV rays by running electricity through xenon gas

Targets Uses UV light to disinfect everything from bedrails to curtains


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