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Q & A: Antibacterial Soaps

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Most recent answer: 04/03/2008
Q:
Iím doing my science project on anti-bacterial soap and which works best. I need information on anti-bacterial soap do have any or know where i can find information?
- Grace
A:
Grace -

What you need to understand here is that all soaps are antibacterial. According to , normal, boring soap will kill about 99.4% of the bacteria on your skin. Antibacterial soaps increase it to only about 99.6% (for triclosan soap). This is not a big difference. But where does the difference come from?

The special thing about antibacterial soaps is that they have antibacterial chemicals like triclosan in them. Triclosan is a chemical that works in a special way to disrupt the functions of bacteria like E. Coli. Different antibacterial soaps use different chemicals in different amounts - to find out what they are, look at the íactive ingredientsí label on the bottle. If youíre trying to compare different antibacterial soaps, what youíre really comparing is the antibacterial chemicals that they contain. That information will be very important for your project.

So whatís the issue? It may not be a big increase in effectiveness, but itís still an improvement - so itís better, right? Well, not necessarily. Thereís actually two potential problems here. The first problem is that you have some good bacteria living on you, too. Some of the bacteria on your skin actually help you out by fighting off other bad bacteria. But these antibacterial chemicals kill them all. By killing the good bacteria on your skin, it can actually make it easier for bad bacteria to make you sick.

The other reason is something called íbacterial resistanceí. This happens because of the 0.4% of bacteria that the soap doesnít kill. Letís put it this way... the first time you wash your hands with an antibacterial soap, you kill off the weakest 99.6% of the bacteria, leaving your whole body free for the strongest 0.4%, which spread out to take up the extra room. The next time you do it, youíll kill off the weakest of those bacteria, giving the strongest ones room to spread out. The cycle repeats until youíve got a whole bunch of bacteria that canít be killed by the chemical youíre using.

The place that this is really a problem is in hospitals. Most people donít really need the extra 2% protection that antibacterial soaps can give them - but sick people in hospitals (and the doctors and nurses who are around them all the time) definitely do. So if people who donít need the extra protection are using it all the time, thereís a lot germs out there that are resistant to the drugs. When those bacteria get into a hospital, the drugs can no longer be used to kill them.

Why donít we get the same problem with regular soaps? Well, to some extent we do. There are a few bacteria that canít be killed by regular soap. But they can be killed by certain antibacterial chemicals. This is why resistance to these chemicals is so important. If the bacteria are already resistant to one thing and then become resistant to another and another and another, sooner or later there wonít be anything left for us to use to get rid of them when they are really a problem.

Also, the antibacterial chemicals called 'antibiotics' only work against bacteria. They donít do anything to kill viruses, which are the cause of most of the really hard-to-treat diseases. However, some disinfectants are fairly effective against viruses.

-Tamara w small changes by Mike W.

(published on 10/22/2007)

Follow-Up #1: antibacterial chemicals

Q:
Hello im doing some research on good and bad bacteria so was really glad i came across the above explanation. The things is you mentioned "Also, antibacterial chemicals only work against bacteria. They donít do anything to kill viruses.." how does this work for antibacterial sprays such as Dettol that claim to kill all known germs, flu VIRUS and other bacteria?
- Sara
London, UK
A:
Sara- Good point, thanks for the correction. What should have been said is that "antibiotics don't kill viruses". I've fixed it above.
There are other chemicals that tend to kill lots of different things, including viruses.

Mike W.

(published on 04/03/2008)

Follow-up on this answer.