An international team of scientists has discovered how an
important natural antibiotic called dermcidin, produced by our skin when we
sweat, is a highly efficient tool to fight tuberculosis germs and other
Their results could contribute to the development of new antibiotics
that control multi-resistant bacteria.
Scientists have uncovered the atomic structure of the
compound, enabling them to pinpoint for the first time what makes dermcidin
such an efficient weapon in the battle against dangerous bugs. Although about
1700 types of these natural antibiotics are known to exist, scientists did not
until now have a detailed understanding of how they work.
How the study was
The study, carried out by researchers from the University of
Edinburgh and from Goettingen, Tuebingen and Strasbourg, is published in
Proceedings of the National Academy of Sciences.
Sweat spreads highly efficient antibiotics on to our skin,
which protect us from dangerous bugs. If our skin becomes injured by a small
cut, a scratch, or the sting of a mosquito, antibiotic agents secreted in sweat
glands, such as dermcidin, rapidly and efficiently kill invaders.
These natural substances, known as antimicrobial peptides
(AMPs), are more effective in the long term than traditional antibiotics, because
germs are not capable of quickly developing resistance against them.
The antimicrobials can attack the bugs' Achilles' heel –
their cell wall, which cannot be modified quickly to resist attack. Because of
this, AMPs have great potential to form a new generation of antibiotics.
Scientists have known for some time that dermcidin is
activated in salty, slightly acidic sweat. The molecule then forms tiny
channels perforating the cell membrane of bugs, which are stabilised by charged
particles of zinc present in sweat. As a consequence, water and charged
particles flow uncontrollably across the membrane, eventually killing the
What they found
Through a combination of techniques, scientists were able to
determine the atomic structure of the molecular channel. They found that it is
unusually long, permeable and adaptable, and so represents a new class of
The team also discovered that dermcidin can adapt to
extremely variable types of membrane. Scientists say this could explain why
active dermcidin is such an efficient broad-spectrum antibiotic, able to fend
off bacteria and fungi at the same time.
The compound is active against many well-known pathogens
such as tuberculosis, Mycobacterium tuberculosis, or Staphylococcus aureus.
Multi-resistant strains of Staphylococcus aureus, in particular, have become an
increasing threat for hospital patients. They are insensitive towards
conventional antibiotics and so are difficult to treat. Staphylococcus
aureusinfections can lead to life-threatening diseases such as sepsis and
pneumonia. The international team of scientists hopes that their results can
contribute to the development of a new class of antibiotics that is able to
attack such dangerous germs.
Dr Ulrich Zachariae of the University of Edinburgh's School
of Physics, who took part in the study, said: "Antibiotics are not only
available on prescription. Our own bodies produce efficient substances to fend
off bacteria, fungi and viruses. Now that we know in detail how these natural
antibiotics work, we can use this to help develop infection-fighting drugs that
are more effective than conventional antibiotics."