Biology Question #528

Peter Griffin, a 15 year old male from Beaufort asks on January 10, 2002,

Do all antibacterial soaps kill bacteria? How do you test if they do?

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The answer

Jennifer Love answered on January 24, 2002

Most antibacterial soaps contain a compound called Triclosan, which kills bacteria on contact. The old belief about Triclosan was that it killed bacteria in a very broad way, as alcohol would. However, new research has determined the precise mode of action of Triclosan. It interferes with a gene involved in bacterial replication, preventing bacteria from dividing and spreading. But it is really the detergent in antibacterial products which do the majority of work in every day applications. Studies have shown that washing your hands with warm to hot water using ordinary hand soap for 30 seconds to 1 minute will remove 99+% of bacteria on the surface of your skin. So, the use of antibacterial soaps might not provide any additional benefit, and may even cause problems down the road. A small fraction of a bacterial population will be resistant to Triclosan, and after you're done killing off the harmful bacteria that are susceptible, you will be left only with resistant bacteria which will divide into more resistant bacteria. Additionally, antibacterial soaps do more than just kill harmful bacteria--they also kill the friendly bacteria your body relies on for health. In some instances, such as in hospital or laboratory use, antibacterial soaps are an important part of hygiene, and serve to prevent the spread of harmful germs. To protect friendly bacteria, and to help reduce the increase in antibiotic-resistant bacteria, the population at large should stay away from antibacterial soaps, unless they're necessary to treat an acute infection.

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