`Supermutant bugs sacrifice themselves to help their colony survive`

In a discovery that can lead to new treatment for drug-resistant bacteria, scientists have found that certain `supermutant` bugs sacrifice themselves to help their colony-mates survive antibiotics.

Updated: Sep 03, 2010, 22:32 PM IST

London: In a discovery that can lead to new
treatment for drug-resistant bacteria, scientists have found
that certain `supermutant` bugs sacrifice themselves to help
their colony-mates survive antibiotics.

Researchers at the Boston University in the US found that
faced with an antibiotic onslaught some `supermutant` bugs,
which are immune to drugs, produce a signalling molecule
called indole to help other bacteria develop drug resistant
`muscle`.

But in so doing they weaken themselves and end up having
their growth rate stunted, said study leader Professor James
Collins.

"We weren`t expecting to find this," Prof Collins was
quoted as saying by the Daily Mail.

"Typically, you would expect only the resistant strains
to survive, with the susceptible ones dying off in the face of
antibiotic stress. We were quite surprised to find the weak
strains not only surviving, but thriving.

"It forced us to rethink our overall strategy to
determine how antibiotic resistance develops and changes in a
population over time."

In the last few years experts have become increasingly
concerned about the rise of superbugs such as MRSA, or
methicillin-resistant Staphylococcus aureus.

They are in a race against time to find new kinds of
effective antibiotics and uncover bacterial Achilles` heels.
But the new findings, the researchers said, would help find
effective treatment against such bugs.

Researchers in the new study, aimed at observing how
Escherichia coli (E.coli) bugs develop resistance under
laboratory conditions, found that indole is the key that
promotes survival in harsh environments.

When normal bacteria are exposed to antibiotics, dead and
dying cells stop producing indole which makes it harder for
those remaining to survive.

By overproducing the molecule, the `supermutants` make
enough to protect the more vulnerable bacteria. However, the
process is costly and reduces the fitness of the supermutants.

"This altruistic behaviour supports a growing body of
evidence that suggests single-celled organisms act as
communities," said Prof Collins.

"We think study of these population-level behaviours will
provide important new understanding of evolution dynamics."
The new study is published in journal Nature.

-PTI