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Shining a (UV) Light on Hospital Infections

UV 1
The UV light device, with its protective shell, used by the Hospital of the University of Pennsylvania’s Environmental Services staff to control infections by killing harmful bacteria.

Every year, 1.7 million Americans acquire infections from their stay in a hospital, nearly 100,000 of which are fatal. These infections, which occur as a result of bacteria like Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile (C. diff), are something health systems are constantly looking for new ways to battle. One of the best ways is through keeping patient rooms and clinical spaces clean, which has sparked interest among health care systems in one particular method as more studies compile evidence in favor of it: cleansing ultraviolet light.

Testing of these lights at Penn began a little over five years ago as more studies provided its worth. Now, there is a rolling, six-foot-tall UV light device assigned to each floor of the Hospital of the University of Pennsylvania (HUP), with many units using one to rid their rooms of harmful organisms after every single discharge.

“From where we were in 2013 to where we are today is a big leap,” said Steve Gaynes, the regional director of Operations and Environmental Services at Penn Medicine. “Adding UV to our process has been a real saver of lives.”

That sentiment isn’t simply anecdotal. Infection numbers kept by the hospital show an approximate two-thirds reduction in patients who acquire infections at HUP. And in a relationship not common across the country, Gaynes and his environmental services (EVS) teams have participated with Penn researchers to study infection control gains in clinical spaces that are in use every single day.

Overall, since the lamps were first introduced at HUP in 2013, the number of patients with bacterial infections has reduced by about two-thirds. A 2015 study of cancer patient floors at the hospital found a 25 percent reduction in C. diff transmission when the UV lights were used. Other studies have yet to be released, but one determined that combining the UV lamps with high-grade cleaning sealants, alone, resulted in a 50 percent reduction in infection transmission.

“We’ve built links between researchers, EVS, and infection control, which is important and unique,” said Jennifer Han, MD, an assistant professor of Infectious Diseases and Epidemiology who is working on the current studies. “Not a lot of other places have something like this, which allows us to make decisions, backed by rigorous data, quickly, which saves lives.”

UV Card
A card used to test the UV light devices to make sure their cycles are calibrated properly to kill both C. diff and MRSA.


The UV devices used at Penn Medicine were carefully chosen. Gaynes and his team considered a variety of factors, including their maneuverability, size, and reach. But the main criteria were two simple numbers:

“The quickest turn time and highest infection kill rate,” Gaynes explained.

Simply put, the devices needed to be able to get in rooms, kill harmful bacteria quickly and completely, and then get back out so the next patient could come in.

To do that, the machines use UV-C light, which breaks down the DNA of organisms like MRSA and C.

“The wavelength range of the light is what breaks bacterium down,” Han said. “And it’s very applicable to many different bacteria. Certain chemicals can be used for certain organisms, but UV can destroy a broader swath of them. That’s its appeal.”

Han said that C. diff, which forms spores that can persist in the environment, is especially difficult to tackle with chemicals and physical cleaning, but the UV machines handle them well.

Each room gets between two and three “cycles” of UV, which last about eight minutes each. Each cycle is conducted at a different point in the room so that the light can reach every area. That’s key, because if a spot remains in shadow, it isn’t getting a cleaning dose of UV. It’s also one of the reasons why Gaynes chose a machine that is so tall and sends its light outward. There is the option of installing overhead light fixtures with UV bulbs built in that send the light downward, but Gaynes decided against them.

“You’d have too many shadows coming from above,” he said.

To determine whether the entire room is getting the right exposure, Gaynes and his team can use testing cards that change colors when they’re exposed to enough UV light to kill C. diff or MRSA. There’s also a gel that can be used to objectively monitor whether a room has been cleaned, as opposed to an old test of whether something “looks clean.”


While Penn Medicine has had remarkable success using the UV technology, Gaynes and Han both note that it isn’t a substitute for physical cleaning. The UV system is more of a fail-safe, being used to eliminate stubborn organisms that remain after physical surface cleaning by staff with cleaning solutions.

“Nothing can replace a training and engaged staff who are motivated to protect the patient,” Gaynes said.

While UV is (literally) a flashy addition to EVS’s efforts, there are many more projects going on and launching soon. These include an underground garage at HUP where beds are disassembled and detail cleaned at least twice a year, a recent switch to a new sporicidal solution for mopping floors that packs an extra punch for C. diff., and new, metal housekeeping carts customized to carry all the necessary materials have recently been introduced to make cleaning quicker and more efficient.

So UV is a groundbreaking addition to the cleaning regimen, but Gaynes doesn’t see it replacing his staffers. It’s simply another tool available to a busy staff.

“The reality is that patients transfer, on average, four times in HUP. They’re not staying in the same room,” Gaynes said. “We need to move quickly and efficiently, so UV adds a highly effective layer to our mission of keeping patients safe.”

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