A light-filled box could blast bacteria from lab coats | Science News for Students

A light-filled box could blast bacteria from lab coats

Teen designs a new method to help keep doctors from spreading germs
May 25, 2017 — 2:15 pm EST
Tatiana Ortiz

Tatiana Ortiz with a model of her coat cleaning box and tiny doctor’s coat. 

C. Ayers/SSP

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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Power Words

(for more about Power Words, click here)

agar     A gelatinous material made from certain marine algae used as a material (and food source) in which to grow bacteria.

asthma     A disease affecting the body’s airways, which are the tubes through which animals breathe. Asthma obstructs these airways through swelling, the production of too much mucus or a tightening of the tubes. As a result, the body can expand to breathe in air, but loses the ability to exhale appropriately. The most common cause of asthma is an allergy. Asthma is a leading cause of hospitalization and the top chronic disease responsible for kids missing school.

bacteria     ( singular: bacterium ) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals).

bleach     A dilute form of the liquid, sodium hypochlorite, that is used around the home to lighten and brighten fabrics, to remove stains or to kill germs.

DNA     (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

E. coli     (short for Escherichia coli) A common bacterium that researchers often harness to study genetics. Some naturally occuring strains of this microbe cause disease, but many others do not.

germ     Any one-celled microorganism, such as a bacterium or fungal species, or a virus particle. Some germs cause disease. Others can promote the health of more complex organisms, including birds and mammals. The health effects of most germs, however, remain unknown.

infection     A disease that can spread from one organism to another. It’s usually caused by some type of germ.

Intel International Science and Engineering Fair     (Intel ISEF) Initially launched in 1950, this competition is one of three created (and still run) by the Society for Science & the Public. Each year now, approximately 1,800 high school students from more than 75 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average of $4 million in prizes. 

microbe     Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.

reflective     Having the quality of reflecting light strongly. Reflective objects can produce a strong bright glare when sunlight bounces off of them. Examples of reflective objects include a mirror, a smooth metal can, a car window, a glass bottle, ice, snow or the watery surface of a lake.

Society for Science and the Public  A nonprofit organization created in 1921 and based in Washington, D.C. Since its founding, SSP has been not only promoting public engagement in scientific research but also the public understanding of science. It created and continues to run three renowned science competitions: the Regeneron Science Talent Search (begun in 1942), the Intel International Science and Engineering Fair (initially launched in 1950) and Broadcom MASTERS (created in 2010). SSP also publishes award-winning journalism: in Science News (launched in 1922) and Science News for Students (created in 2003). Those magazines also host a series of blogs (including Eureka! Lab).

spectrum     (plural: spectra) A range of related things that appear in some order. (in light and energy) The range of electromagnetic radiation types; they span from gamma rays to X rays, ultraviolet light, visible light, infrared energy, microwaves and radio waves.

survey     (v.) To ask questions that glean data on the opinions, practices (such as dining or sleeping habits), knowledge or skills of a broad range of people. Researchers select the number and types of people questioned in hopes that the answers these individuals give will be representative of others who are their age, belong to the same ethnic group or live in the same region. (n.) The list of questions that will be offered to glean those data.

ultraviolet light     A type of electromagnetic radiation with a wavelength from 10 nanometers to 380 nanometers. The wavelengths are shorter than that of visible light but longer than X-rays.

wavelength     The distance between one peak and the next in a series of waves, or the distance between one trough and the next. Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.


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