This new class of drug found in soil could help fight rising antibiotic resistance and tackle MRSA

Antibiotic resistance was recently described by the government’s chief medical officer as a “ticking time bomb” that should rank alongside terrorism as threats to the nation. 

Each time a bacteria becomes resistant to a particular strain of antibiotics, either due to the bacteria’s ability to evolve or due to claims the NHS is oversubscribing drugs unecessarily, we take a step closer to widespread resistance. In fact, in the absence of new therapies, mortality rates from untreatable infections globally are predicted to rise more than tenfold by 2050. 

 Although antibiotics have been developed since the 1930s, the main classes of antibiotic in use today were discovered around than 30 years ago. When bacterial immunity catches up with these, diseases once easily treatable may revert to being a death sentence again, such as Diphtheria and Gonorrhoea. Natural products (NPs) made by cultured bacteria were a major source of clinically useful antibiotics but the practice was largely abandoned due to a lack of bacteria diversity being discovered. 

Now, researchers from The Rockefeller University have developed a way to sequence DNA from soil samples and, in the process, have discovered malacidins – a distinctive class of antibiotics that are commonly encoded in soil microbiomes but have never been gathered using NP.

The benefit of the sequencing process is that is bypasses the need to grow microorganisms first meaning it can be used to quickly mine new drug candidates from “diverse environmental sources”.

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When tested on rats, the malacidins family of antibiotics was found to kill several multidrug-resistant, disease-causing bacteria, notably the methicillin-resistant Staphylococcus aureus (MRSA) skin infection.

Malacidins fight bacteria differently to most other drugs by attacking a key part of the bacterial cell wall which, during lab tests, didn’t develop any resistance. 

The research also found that soil samples from at least 17 US states, predominantly in the west, contain NPs from the malacidin clade meaning there is an abundant source.