UV Disinfectant

UV Disinfectant Photo Credit: Clipart.com

Short-wave ultraviolet radiation can clear dangerous germs from hospital rooms.


Enlightened hospital sanitation. I'm Bob Hirshon and this is Science Update.

Ultraviolet radiation causes sunburns and skin cancer. But it also kills disease-causing bacteria. Recently, scientists from Duke University Medical Center and the University of North Carolina Hospital system used a UV-emitting machine to disinfect actual hospital rooms, right after the sick patients checked out. Duke infectious disease specialist Deverick Anderson says they looked at three tough bugs, including antibiotic-resistant staph, or MRSA.

We found that we were able to reduce the amount of bacteria that was present by upwards of 90-95 percent. So, a lot.

Anderson notes that the UV radiation bounces all over the room, so it works even in shadows. The next step is to find out if the UV system actually reduces patient infections, which they're currently studying in nine hospitals. I'm Bob Hirshon for AAAS, the Science Society. 

Making Sense of the Research

One of the frustrating realities of medicine is that hospitals are hard places to keep clean. After all, they're populated by sick people carrying all sorts of infectious agents. And ordinary surfaces like doorknobs and bed frames can become breeding grounds for those germs.

Right now, those surfaces are usually cleaned with disinfectants and detergents, which aren't always as effective as they should be, especially against powerful bugs like methicillin-resistant Staphylococcus aureus, or MRSA, which has caused serious and deadly infections in hospitals in recent years. It's been shown that short-wave ultraviolet (UV) light can kill those bacteria and others in the lab. The question, though, is whether it can be used in a practical setting.

This experiment answers part of that question. The researchers took UV light-emitting machines into actual hospital rooms, just after patients with infections like MRSA had been sent home. They ran the machine in the empty room for a certain amount of time, depending on specific factors like the size of the room. (The room must be empty, since the UV light is dangerous to humans.) They tested bacteria counts on surfaces like doorknobs and bedposts before and after the UV treatment.

The results indicate that the UV machines were very effective in disinfecting the surfaces. As you heard, short-wave UV radiation can also penetrate dark and shadowy areas that ordinary light doesn't reach. The UV treatment also offers other advantages over conventional cleaning: unlike humans with spray bottles and rags, it's not going to miss or forget certain areas. It also doesn't require humans to come in such close contact with the germs. 

Still, there's another question to answer: Does using the UV machine to disinfect hospital rooms actually result in fewer patient infections? That question couldn't be addressed without knowing that the machine does, in fact, kill germs effectively. Now, there's a study underway in nine different hospitals, where staff have been trained to use the UV machines. If using the machines translates into healthier patients, expect to see more and more of them in hospitals around the world.

Now try and answer these questions:

  1. What was already known about ultraviolet radiation and disease-causing bacteria?
  2. What did this study add to that knowledge? What question remains unanswered?
  3. Why do you think it's important to do this kind of research one step at a time? For example, researchers could have brought the machines into hospitals and measured the effects on patients, based just on the knowledge that UV can kill germs. Why didn't they do that?
You may want to check out the October 26, 2012, Science Update Podcast to hear further information about this Science Update and the other programs for that week. This podcast's topics include: Medical implants that just melt away, how cancer research could make the plastics industry less dependent on fossil fuels, why ultraviolet light is cleaning up hospital rooms, scientists find a surprising new source of re-programmable cells in amniotic fluid, and a new genetic test that could help babies in the neonatal intensive care unit.
For more on germs and technology using UV light, see the Science Updates Germy Surfaces, Antibacterial Sludge, Antibacterial PollutionSolar Blind, and Talking Lights.

Going Further

For Educators

For more on germs and technology using UV light, see the Science Updates Germy SurfacesAntibacterial SludgeAntibacterial PollutionSolar Blind, and Talking Lights.

The Invisible Kingdom lesson helps students develop an understanding of the characteristics and diversity of microbial life.

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