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Fascinating Facts About Germs: Viruses, Bacteria, Antibiotics
Six questions about germs—and how to beat them before they beat you.

newsletter-graphic1. How long do germs stay on surfaces?
Depending on the type of germ and the environmental conditions, they can survive from a few hours to weeks.

2. Is the five-second rule real?
It doesn’t seem to be. A study in the April 2007 Journal of Applied Microbiology found that salmonella could survive up to 28 days on a dry surface and be transferred “almost immediately on contact.” Other less scientific studies have found different results. It likely just depends on what’s on your floor (which doesn’t have to be visibly dirty to be contaminated).

3. The news and talk shows are always doing segments on the amount of germs on doorknobs and other common surfaces. Do I really need to worry about those?

Bacteria and germs are everywhere and can last for a long time on surfaces such as doorknobs. You shouldn’t worry about them excessively though. Just wash your hands regularly, especially before eating. Alcohol-based hand sanitizers, now easily available at grocery stores and pharmacies, are also an excellent way to get rid of germs.


4. How does feces get onto doorknobs, anyway?
Unfortunately, even with regular washing, people’s hands can still be contaminated with small traces of bugs, which can then stick to any surface they come in contact with.

5. What is the difference between viruses and bacteria?
Bacteria are single-celled organisms. They have a protective cell wall and all the structures necessary to live and reproduce independently. Viruses are simply DNA or RNA surrounded by a protein coat. In order to reproduce, they must insert themselves into the cells of a plant, animal or even bacterium, where they commandeer their host cell’s equipment.

6. Why don’t antibiotics kill viruses?
The structure and metabolism of bacteria and viruses are so different that antibiotics don’t affect viruses. For example, some antibiotics attack a bacterium’s cell wall. Viruses don’t even have cell walls! There are medications that combat some viruses, but alas, there’s nothing to kill the common cold, the most frequent viral infection.


Eva F. Briggs, M.D., board-certified family physician in Marcellus, N.Y.

Emmanuel Rodriguez, M.D., M.P.H., infectious-disease specialist, NorthReach Internal Medicine Clinic, Marienette, Wis.; attending physician and hospital epidemiologist, Bay Area Medical Center; board certified in internal medicine.

Shirley Tozzi, M.D., infectious-disease specialist, Caritas St. Elizabeth’s Medical Center, Boston, Mass.

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Last updated and/or approved: October 2010.
Original Q&As appeared in various issues of the former print magazine. Bios current as of those issues. This general health-care information is not meant as individual advice. Please see our disclaimer.
Comments (2)add comment
written by megan , July 14, 2014

always make sure you wash your hand s properly and i agree lauren use hand sanitizer it kills 99.99% of your germs
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written by lauren , September 16, 2011

kissing someone is cleaner then shaking someones hands
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