Extreme medicine: The search for new antibiotics




The problem is they just don’t have the natural diversity of compounds that have evolved over billions of years as defense mechanisms for wild bacteria and fungi.

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“We need new scaffolds, new structures and that is what natural products bring,” Corre says.

FIVE MILLION TRILLION TRILLION BACTERIA

In the chase for new compounds generated by microbes to fight off their foes, scientists have no shortage of targets. Humans share the Earth with an awful lot of bacteria – around 5 million trillion trillion of them, according to an estimate in 1998 by scientists at the University of Georgia. That’s a 5 followed by 30 zeroes.

And as well as hunting in extreme places, there is a lot more scientists can do to explore the potential of better-known bacteria, such as species of Streptomyces found in the soil, long a rich source of antibiotics. Streptomycin, a commonly used antibiotic, was the first cure for tuberculosis and saved many lives from being lost to the lung disease until the bacteria that causes it began to develop resistance.

After publication of the first genome for a strain of Streptomyces bacteria in 2002, researchers can see that much of the antibiotic potential of this vast family of organisms remains untapped.

The DNA analysis showed that up to 30 different compounds could be extracted from just this one strain of Streptomyces – many of them ones that haven’t yet been examined for their bug-killing capacity.

Understanding the genetic coding also opens up the possibility of developing ways of turning microbial genes on or off to generate production of a specific antibiotic.

This can involve removing repressors that silence gene expression or adding activators to turn them on. Scientists are also using synthetic biology to insert genetic sequences into easily managed host cells to produce a certain compound.

The field is exploding. China’s BGI, for example, one of the world’s biggest genomics centers, is sequencing thousands of different bacteria, and similar work at other labs is adding to a mountain of data for scientists to work through.

It also provides insights into how antibiotic resistance occurs, with researchers at Britain’s Wellcome Trust Sanger Institute this month reporting a new way to identify such gene changes, potentially paving the way to more targeted treatments.

These advances are tempting some large drugmakers back to the antibiotic space, with Swiss-based Roche now looking to apply its skills in genetics and diagnostics in antibacterial research.

France’s Sanofi, too, is also paying more attention by striking a deal with German research center Fraunhofer-Gesellschaft to scour the natural world for new antibiotics, while Britain’s GlaxoSmithKline says it remains committed to the field.

Yet the overall industry effort is paltry when compared with the billions of dollars spent on other disease areas, leaving scientists worried as to whether their promising ideas will find a commercial sponsor to bring them to market.

It is a commercial gap that alarms policymakers, too.

“Antimicrobial resistance is not a future threat looming on the horizon. It is here, right now, and the consequences are devastating,” Margaret Chan, Director-General of the World Health Organization, told a ministerial conference on antibiotic resistance in June. (Reuters)[eap_ad_3]



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