Frisky bacteria war on drugs revealed

Streptococcus bacteria

Ever since medicine declared war on bacteria with the discovery of penicillin, the two have been locked in an arms race.

Antibiotics are met by resistance from germs; so researchers develop new drugs and germs become resistant again.

Now some scientists believe genetics will be the new weapon in the fight, with doctors consulting bacterial genomes when treating disease.

This week a team at the Wellcome Trust Sanger Institute published a paper in the journal Science, which they say shows the first genetic picture of the evolutionary war between medicine and bacteria.

Bacterial genetics can be tricky. With humans, one person's DNA is passed on to their children, then to their children, and so on down the family tree.

Bacteria are altogether more frisky.

They pass DNA onto their descendants when they divide in two, but they also swap DNA with other bacteria, changing their genetic code.

It is like popping to the shop and changing eye colour with someone at the checkout.

This study has managed to tease out the differences between the two ways of passing on DNA in Streptococcus pneumoniae and draw its family tree.

From the lab to the hospital

The researchers were able to show how the species responded to different antibiotics, how it became resistant, where it became resistant and how the resistance spread around the world.

It is the first time the whole of a genome has been studied to measure the genetic response to medicine.

Other studies have come to some of the same conclusions, but as a review in the same journal said: "Suggesting that we knew all this before however misses the importance of their study, in which a single experiment provided more information than has been achieved over 15 years of research."

Studying the whole of a genome is getting cheaper and Dr Stephen Bentley, from the Sanger Institute, believes it could change the way we treat illnesses.

He told the BBC: "Potentially every time someone is ill we could isolate the genome of a bacterial infection, determine if it is resistant, how it will behave in humans and match it up to a database to monitor the spread of an outbreak."

Writing in Science, Professors Mark Enright and Brian Spratt, reviewed the study: "The ease with which investigators can now obtain whole genomes of bacterial pathogens is opening up a number of questions that previously were impossible or difficult to address.

"One of these is how virulent or high drug resistant strains of bacterial pathogens spread within hospitals and nursing homes within a region."

Dr Bentley thinks pathogen genomics could become part of normal hospital practice in five to 10 years' time.

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