Tuesday October 23, 2018

Antibiotic Resistance Spreads From Animals To Humans At Faster Pace

Even Colistin is losing its potency against so-called "superbugs".

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Antibiotic
Chinese researchers identify potential new antibiotic. Pixabay
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Scientists have expressed shock at the speed at which resistance to powerful antibiotics spreads from animals to humans, as new research has shown how genetic mutations in pathogens likely spread from a pig farm in China to affect human and animal species across the world in the space of just a few years.

The antibiotic Colistin is known as a medicine of “last resort,” used to save people’s lives when all other drugs have failed. Lead researcher Professor Francois Balloux, director of the Genetics Institute at University College London says it has become an important last line of defense as other antibiotics have become less effective.

“It was used a bit in the clinic. And then there were some worries about toxicity and side-effects. And it was mostly used in agriculture then, in pigs and a bit in chickens. But recently, as we are running out of drugs, people actually have become a bit more interested in using it, and it has been used quite extensively recently over the last five to 10 years in the clinic,” says Balloux.

Now even Colistin is losing its potency against so-called “superbugs”.

Fast mutation

Deadly pathogens like E. Coli or salmonella can mutate and develop resistance to antibiotics. Balloux’s research identifies the speed at which the mutant gene that gives resistance to Colistin emerged in the mid-2000s.

“It was a single mergence, it happened only once. And it jumped very, very likely from pigs, probably in China, and it spread extremely rapidly throughout the world. And it also spread in all sorts of different species, and affects humans. So now we find it in in many of the most important pathogens we face in hospitals. And it is absolutely everywhere,” Balloux told VOA.

The resistance has even been found in pathogens in the seawater on Brazilian beaches. Balloux notes his study focused on just one resistant gene, but many pathogens are developing other forms of resistance.

 

Britain’s chief medical officer warned recently that anti-microbial resistance could lead to the “end of modern medicine.”

“Think about common operations, caesarean sections, replacement hips. Those would become much more risky if we did not have effective antibiotics. Superbugs kill and they’re on the rise,” Professor Sally Davies told delegates at an October conference on anti-microbial resistance in Germany.

Scientists are working on “boosting” existing drugs like Colistin to give them added power against resistant pathogens.

Also Read: Antibiotics in puget sound mussels

Longer-term, researchers say more investment is needed in developing new drugs, along with a rethink of the way antibiotics are used in agriculture and in the clinic. (VOA)

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Invasive Species May Not Be All Bad: Scientists

An active debate among biologists about the role of invasive species in a changing world is going on

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Invasive Species
The invasive European green crab is tearing down ecosystems in Newfoundland and building them up on Cape Cod. VOA

Off the shores of Newfoundland, Canada, an ecosystem is unraveling at the hands (or pincers) of an invasive crab.

Some 1,500 kilometers (930 miles) to the south, the same invasive crab — the European green crab — is helping New England marshes rebuild.

Both cases are featured in a new study that shows how the impacts of these alien invaders are not always straightforward.

Around the world, invasive species are a major threat to many coastal ecosystems and the benefits they provide, from food to clean water. Attitudes among scientists are evolving, however, as more research demonstrates that they occasionally carry a hidden upside.

“It’s complicated,” said Christina Simkanin, a biologist at the Smithsonian Environmental Research Center, “which isn’t a super-satisfying answer if you want a direct, should we keep it or should we not? But it’s the reality.”

Simkanin co-authored a new study showing that on the whole, coastal ecosystems store more carbon when they are overrun by invasive species.

Good news, crab news

Take the contradictory case of the European green crab. These invaders were first spotted in Newfoundland in 2007. Since then, they have devastated eelgrass habitats, digging up native vegetation as they burrow for shelter or dig for prey. Eelgrass is down 50 percent in places the crabs have moved into. Some sites have suffered total collapse.

That’s been devastating for fish that spend their juvenile days among the seagrass. Where the invasive crabs have moved in, the total weight of fish is down tenfold.

The loss of eelgrass also means these underwater meadows soak up less planet-warming carbon dioxide from the atmosphere.

In Cape Cod, Massachusetts, the same crab is having the opposite impact.

Off the coast of New England, fishermen have caught too many striped bass and blue crabs. These species used to keep native crab populations in check. Without predators to hold them back, native crabs are devouring the marshes.

But the invasive European green crab pushes native crabs out of their burrows. Under pressure from the invader, native crabs are eating less marsh grass. Marshes are recovering, and their carbon storage capacity is growing with them.

Invasive species
In this May 8, 2016 photo, eelgrass grows in sediment at Lowell’s Cove in Harpswell, Maine. VOA

Carbon repositories

Simkanin and colleagues compiled these studies and more than 100 others to see whether the net impact on carbon storage has been positive or negative.

They found that the ones overtaken by invasive species held about 40 percent more carbon than intact habitats.

They were taken by surprise, she said, because “non-native species are thought of as being negative so often. And they do have detrimental impacts. But in this case, they seem to be storing carbon quicker.”

At the Smithsonian Environmental Research Center where she works, the invasive reed Phragmites has been steadily overtaking a marsh scientists are studying.

Phragmites grows much taller, denser and with deeper roots than the native marsh grass it overruns.

But those same traits that make it a powerful invader also mean it stores more carbon than native species.

“Phragmites has been referred to as a Jekyll and Hyde species,” she said.

Not all invaded ecosystems stored more carbon. Invaded seagrass habitats generally lost carbon, and mangroves were basically unchanged. But on balance, gains from marsh invaders outweighed the others.

Invasive species
Phragmites plants growing on Staten Island draft in a breeze in the Oakwood Beach neighborhood of Staten Island. VOA

Not a lot of generalities

To be clear, Simkanin said the study is not suggesting it’s always better to let the invaders take over; but, it reflects an active debate among biologists about the role of invasive species in a changing world.

“One of the difficult things in the field of invasion biology is, there aren’t a lot of generalities,” said Brown University conservation biologist Dov Sax, who was not involved with the research. “There’s a lot of nuance.”

The prevailing view among biologists is that non-native species should be presumed to be destructive unless proven otherwise.

When 19 biologists wrote an article in 2011 challenging that view, titled, “Don’t judge species on their origins,” it drew a forceful rebuke from 141 other experts.

Sax said the argument is likely to become more complicated in the future.

Also Read: Climate Change Not A Hoax: Trump

“In a changing world, with a rapidly changing climate, we do expect there to be lots of cases where natives will no longer be as successful in a region. And some of the non-natives might actually step in and play some of those ecosystem services roles that we might want,” he said.

“In that context, what do we do? I definitely don’t have all the answers.” (VOA)