Bacteria 'sacrifice' themselves to prevail

CERTAIN "supermutant" bacteria sacrifice themselves to help their colony-mates survive antibiotics, research has found.

To start with, only a few "supermutant" bugs are immune to the drugs. Faced with an antibiotic onslaught, they manufacture a signalling molecule called indole which causes other bacteria to develop drug resistant "muscle". But in so doing they weaken themselves and end up having their growth rate stunted.

Study leader Professor James Collins, from Boston University in the US, said: "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 past few years experts have become increasingly concerned about the rise of superbugs such as MRSA (methicillin-resistant Staphylococcus aureus). Scientists are in a race against time to find new kinds of effective antibiotics and uncover bacterial Achilles' heels.

The new study, published in the journal Nature, involved observing how E coli bugs develop resistance under laboratory conditions. "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."