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Cells, Microbes & Viruses / Re: Antibacterial handwashes
« on: 08/12/2004 09:23:10 »
The following might not really contain an answer to your question, but it is associated.
When I was a biology student we performed an experiment that tested different soaps and alcohol for desinfection. Toiletpaper was tested as well. It was a simple experiment that used petridishes with sterile solid medium and petridishes with a marker strain, Serratia marcesens, a good marker because of its red colonies.
Of course we ample hands available. First we needed to press our left and right hand on a sterile petridish, separate dishes. Then take 1, 2, 3, 4, 5, 6, 7 or 8 layers of toilet paper and push your left hand with the paper in between on the plate with serratia (so to check how many layers you need before no bacteria would go through). Then press both hands on fresh sterile plates again. Then the pairs of hands washed only water or with soap or with antibacterial soap. Press both hands on petridish. Then 1 or 5 minutes in a layer of alcohol. And again on a fresh steril petridish. Make sure to label everything well! Petridishes where incubated overnight and analysed the next day.
Results:
You need a couple of layers before hardly any bacteria arrive at your hands. So washing your hands is a good hygenic thing to do. But while washing you infect your other hand as well. There were minor differences among the use of water, normal soap or antibacterial soap, with the soaps removing more bacteria. Drying hands was a definite major improvement (sorry not mentioned above, but this step was included as well). Also alcohol killed of the bugs very nicely.
Conclusion:
If you want to save the rainforest and do not want to use a whole tree to wipe of your ass then wash your hands with water or mild soap and dry thoroughly. The indigenous microflora on your hands protect against evil invaders. Cleaning your hands to rigourously also kills them of, making your hands prone to investation with them evildo-ers.
--- man is twice the worm it used to be ---
When I was a biology student we performed an experiment that tested different soaps and alcohol for desinfection. Toiletpaper was tested as well. It was a simple experiment that used petridishes with sterile solid medium and petridishes with a marker strain, Serratia marcesens, a good marker because of its red colonies.
Of course we ample hands available. First we needed to press our left and right hand on a sterile petridish, separate dishes. Then take 1, 2, 3, 4, 5, 6, 7 or 8 layers of toilet paper and push your left hand with the paper in between on the plate with serratia (so to check how many layers you need before no bacteria would go through). Then press both hands on fresh sterile plates again. Then the pairs of hands washed only water or with soap or with antibacterial soap. Press both hands on petridish. Then 1 or 5 minutes in a layer of alcohol. And again on a fresh steril petridish. Make sure to label everything well! Petridishes where incubated overnight and analysed the next day.
Results:
You need a couple of layers before hardly any bacteria arrive at your hands. So washing your hands is a good hygenic thing to do. But while washing you infect your other hand as well. There were minor differences among the use of water, normal soap or antibacterial soap, with the soaps removing more bacteria. Drying hands was a definite major improvement (sorry not mentioned above, but this step was included as well). Also alcohol killed of the bugs very nicely.
Conclusion:
If you want to save the rainforest and do not want to use a whole tree to wipe of your ass then wash your hands with water or mild soap and dry thoroughly. The indigenous microflora on your hands protect against evil invaders. Cleaning your hands to rigourously also kills them of, making your hands prone to investation with them evildo-ers.
--- man is twice the worm it used to be ---