A light-filled box could blast bacteria from lab coats

LOS ANGELES, Calif. — Tatiana Ortiz is on a crusade. Her mission? To help prevent patients from picking up diseases while they’re in the hospital. The 16-year-old sophomore at Flour Bluff High School in Corpus Christi, Texas, has figured out a way to clean a doctor’s white coat. But the teen isn’t using soap and water. Instead, she’s built a box filled with light. It disinfect a coat in 90 seconds.

And here’s why that’s important. A doctor’s white coat can pick up a lot of germs over the course of a day — especially in a hospital or clinic full of sick people.

Lab coats can be dry cleaned or washed in hot water and bleach to kill germs. But some people still don’t do it as often as they should. A 2007 survey of doctors at the University of Maryland in Baltimore found that 64 percent hadn’t washed their white coats in a week. Almost one in six more hadn’t washed their coats in almost a month. And more than one in four of the coats hosted germs.

Numbers like that terrify Tatiana. She has good reason to be scared. “I have asthma,” she explains. “When I get sick, I get really sick.” The teen is especially worried about bacteria that can resist some of the drugs designed to kill them. “It’s terrifying to me to know that there are microorganisms out there that we cannot cure,” she says. That motivates her to find ways to kill disease-causing germs and prevent them from spreading.

Tatiana brought a model of her coat-disinfecting box to the Intel International Science and Engineering Fair (ISEF). This yearly competition was created by Society for Science & the Public and is sponsored by Intel. It brings together high school students from around the world to show off their research projects. Last week, almost 1,800 teens from more than 75 countries took part. (The Society also publishes Science News for Students and this blog.)

What she did

People who go to the hospital with a sickness or injury will usually get well. But some will unfortunately pick up some infection during their stay. In fact, on any day, about four in every 100 hospital patients will be dealing with a  disease they picked up as a patient being treated for something else.

When Tatiana does science fair projects, she sees them as opportunities to do battle against bacteria. Her project last year looked for sprays and films that could keep microbes off doctors’ gloves. But as she worked, she found a bigger target. “This year, I wanted to figure out a method to clean lab coats,” she says. “The lab coats and scrubs that a lot of medical personnel wear are a major contributor to hospital-acquired infections.”

Tatiana wanted to find a way to clean a doctor’s lab coat between every single patient. She turned to ultraviolet, or UV, light. This is a part of the light spectrum that is close to violet but that our eyes can’t see directly (we perceive UV light as blue). UV light can be divided into categories by its wavelength. Short wavelength UV light — known as UV-C light — can shut down nasty microbes by breaking parts of their DNA.

To harness the bacteria-busting power of UV-C, the teen designed a special cabinet. UV-C light is dangerous; even short exposures can damage skin and eyes. So Tatiana built a large black box, about the size of a dishwasher. She lined it with reflective aluminum to bounce light around inside it. Then she hooked up four UV-C lightbulbs that she bought at a hardware store to light the inside. In the top, she designed a lid with a hanger for a white coat. When needed, someone could put a coat on the hanger and drop it into the box. The lights would turn on and kill any bacteria.

To find out if her box would work, Tatiana worked with a local hospital’s lab. She wanted to mimic how a coat might pick up germs.

She started by cutting a white coat into more than 100 pieces. She divided the pieces into groups and dripped a measured amount of E. coli bacteria (in a salty solution) onto each. Then, she rubbed the germ-laden cloth onto another coat, concentrating on areas that she saw doctors touch often — the upper pocket, lower pocket, button and sleeve.

The teen swabbed those frequently touched areas onto agar plates. These are plastic dishes with food for bacteria. When clumps of bacteria grew on the plates, Tatiana knew the lab coat had hosted germs that could be infect someone.

To test how much light would it take to kill those germs, Tatiana placed another group of her germ-treated bits of coat in the UV-C box. She left them there for 30, 60 or 90 seconds. Then she swabbed the coat material onto more plates and waited to see if bacteria would grow.

UV-C light is a great coat disinfectant, Tatiana showed. After 30 seconds of exposure, the average growth of microbe was 88 percent lower than from coat material not irradiated with UV light. A 60 second exposure was about equally useful. And after 90 seconds, the coat cloth hosted 99.9 percent fewer germs than non-irradiated cloth. “I was really happy with my results,” the teen reports.

Laboratories already use UV-C light to sterilize goggles, gloves and instruments. Tatiana envisions using it one day for lab coats, too. The light wouldn’t clean dirt or stains. But it would kill most of the germs that could infect a patient.

Other scientists have had a similar idea. One company even designed a closet to clean clothing in hospitals. But for Tatiana, the most important thing is spreading the word about the need to keep lab coats clean. “I want people to have this idea because to me, science is about learning and taking ideas that we already have and then sharing them so that everyone can use them,” she says.

After tackling lab gloves and lab coats, the teen has yet to come up with a new target for her next germ war. She’s now focused on improving her lab coat cleaning design, and adding features such as an automatic light shut-off to protect the unwary from being exposed to the dangerous light. But her crusade against disease hasn’t stopped. “I know what it’s like to always be sick and not even be able to do everyday activity like go outside and go running or go play,” she says. With enough research, Tatiana hopes that everyone has access to better protection from infection.

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