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Thursday, July 19, 2018

Paper Clip: Hunt for new antibiotics hits pay dirt

According to the paper, malacidins are “a distinctive class of antibiotics that are commonly encoded in soil microbiomes but have never been reported in culture-based NP (Natural Products) discovery efforts”.

By: Express News Service | Published: February 15, 2018 1:03:15 am
Hunt for new antibiotics hits pay dirt Gram-negative bacteria can cause cholera, pneumonia, sexually transmitted diseases, and plague.

The Scottish physician Alexander Fleming revolutionised the world of medicine in 1924 by discovering penicillin, the world’s first true antibiotic. Nine decades later, medical practitioners are running out of antibiotics that would cure diseases caused by drug-resistant bugs. According to the Review on Antimicrobial Resistance (AMR), a study commissioned by the British Prime Minister to analyse the global problem of rising drug resistance and propose concrete actions to tackle it internationally, which submitted its report in 2016, antibiotics-resistant diseases will claim 10 million lives every year by 2050.

As researchers around the world scramble to cultivate new molecules that can destroy disease-causing microorganisms, scientists from The Rockefeller University in New York have reported the discovery of a new class of antibiotics called malacidins, which are produced by microorganisms that live in soil and dirt.

According to the paper, malacidins are “a distinctive class of antibiotics that are commonly encoded in soil microbiomes but have never been reported in culture-based NP (Natural Products) discovery efforts”.

Malacidins, the researchers say, “are active against multidrug-resistant pathogens, sterilise methicillin-resistant Staphylococcus aureus (MRSA, which kills 20,000 people every year in the US) skin infections in an animal wound model and did not select for resistance (i.e., did not trigger resistance) under our laboratory conditions”.

The malacidins was tested on rats with MRSA skin infections. The condition was cured, and even after 20 days of continued contact with malacidins, the rodents did not experience any side effects. This has raised hopes for the discovery of a non-toxic alternative to the current range of available antibiotics.

Dr Brady’s team used gene sequencing to clone DNA from more than 1,000 soil samples collected from across the US. After they had sorted through the material, the scientists found, said Brady, that “most of what’s there is completely unknown, and that’s the future”.

“Our idea is, there’s this reservoir of antibiotics out in the environment we haven’t accessed yet,” Brady told The Washington Post. This, however, is just the principle — as Dr Brady was quoted by The Post, “You won’t find this antibiotic at your pharmacy next week”.

The second note of caution is that this potentially wonderful new drug cannot, as yet, treat all infections. Malacidins only target gram-positive bacteria. The BBC quoted Prof Colin Garner, from Antibiotic Research UK, as saying, “Our concern are the so-called gram-negative bacteria, which are difficult to treat and where resistance is on the increase.”

Gram-negative bacteria can cause cholera, pneumonia, sexually transmitted diseases, and plague.

TACKLING DRUG RESISTANCE: Published in Nature Microbiology on February 12, 2018 (Open Source). Authors: Sean F Brady, Bradley M Hover, Jeremy G Owens, and Others

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