Sweating appears to be an essential part of the body鈥檚 defence against bacteria, researchers have discovered.
The skin is known to release antimicrobial chemicals when wounded. Now Birgit Schittek and her team at the University of T眉bingen in Germany have discovered that even intact skin exudes a small antibiotic protein called dermcidin in sweat. 鈥淭his is the first antimicrobial compound in sweat ever to be described,鈥� Schittek says.
Her group tested dermcidin against four common species of bacterium. All of them died, says Schittek, including the potentially lethal bugs Escherichia coli and Staphylococcus aureus.
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These species represent two distinct types of bacteria, known as Gram-negative and Gram-positive. The antibiotic鈥檚 success against both types suggests it will work against a wide range of bugs.
Robert Hancock, an expert in antimicrobials at the University of British Columbia in Vancouver, thinks Schittek is right that dermcidin is an important part of our 鈥渋nnate鈥� immune system, the constant low-level defence that wards off infections. The more familiar targeted immune response that involves white blood cells and antibodies only kicks in if things get out of hand.
Dermcidin has an unusual structure, Hancock says. Most antibiotics are positively charged, allowing them to interact with the bacterial cell membrane, but dermcidin has a slight negative charge. 鈥淭his suggests that it operates in a completely different way,鈥� he says.
If dermcidin turns out to be effective against bacteria resistant to other antibiotics, Schittek鈥檚 discovery could have commercial potential. She has already isolated the gene for it, raising the possibility of mass-producing it.
Journal reference: December issue of Nature Immunology