Re: What are some accurate labratory techniques obtaining normal skin flora?

The best way to collect bacteria, yeast and mold from skin is to use a cellulose sponge moistened with neutralizing buffer or microbiological growth medium. You may use a non-selective broth such as trypticase soy broth or brain heart infusion broth if you wish (see some of the bioloigcal suppliers links in the Try the links in the MadSci Library for more information on Microbiology. purchase pre-moistened cellulose sponges from International Bioproducts 800 729-7611. Be careful if you use commercial sponges from retail outlets in that many brands are packaged with an anti-microbial substance.

Rub the sponge across the hands and then place the sponge in a small plastic bag. Add 9-10 ml of buffer and squeeze the sponge to release the microorganisms into the buffer. You may then remove the liquid from the bag. This liquid should represent the microbiological flora that was recovered from your hand (times 10). If you plate 1 ml of the liquid and 25 colonies grow then you should multiply by a factor of 10 since you added 10 ml of buffer. Twenty-five colonies would then represent 250 colonies/sponge.

It is the friction and the rough surface of the sponge which removes microorganisms from the pores of the skin. Hot water also helps to open the pores of the skin to allow the organisms to be rinsed away with soap.