Dangerous bacteria that have become resistant to conventional antibiotics can now be killed in minutes using pom-pom-shaped molecules that rip apart their walls.
The new molecules are cheap and easy to make and bacteria don’t appear to become resistant to them, even over hundreds of generations. “We’re getting a lot of interest from pharmaceutical companies about developing them further,” says Neil O’Brien-Simpson at the University of Melbourne in Australia, who is part of the team that invented them.
Antibiotics used to be highly effective at treating bacterial infections but are now losing potency as bacteria evolve ways to resist them. Over a million people died of antibiotic-resistant bacterial infections worldwide in 2019 alone – more than died from either AIDS or malaria.
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The alternative treatments being developed by O’Brien-Simpson and his colleagues are made of strings of amino acids that are joined at a central point, like a pom-pom. They can be tailored to kill different kinds of drug-resistant bacteria by modifying the number of strings and the sequences of amino acids within them.
The pom-pom molecules appear to kill bacteria by penetrating their inner membrane and ripping them open in minutes. “Under a microscope, you can see the contents of the bacteria literally pouring out,” says at the University of Melbourne, who is co-developing them.
But they don’t appear to harm human or other animal cells. This is because the pom-pom strings are positively-charged, which attracts them to the negatively-charged walls of bacteria, but not to animal cells, which have a neutral charge, says Qiao.
The researchers recently tested one of their pom-pom designs in mice infected with MRSA (methicillin-resistant Staphylococcus aureus) – one of the most common types of drug-resistant bacteria – and found that it killed over 98 per cent of the MRSA in their bodies, without causing any side effects.
Other variations have been shown to kill drug-resistant strains of Escherichia coli (E. coli), Pseudomonas aeruginosaĚý˛ą˛Ô»ĺ Acinetobacter baumannii bacteria.
One of the main advantages is that bacteria don’t appear to develop resistance to the pom-pom molecules, even when exposed for over 600 generations. This may be because the molecules target the whole inner membrane of the bacteria rather than one specific molecule, which is the case for conventional antibiotics, says O’Brien-Simpson. Their rapid killing time also makes it harder for bacteria to develop resistance, he says.
“The fact that these don’t seem to lead to resistance is really important,” says at the University of Technology Sydney in Australia. However, we still need to see if they work in people, she says.
The team now plans to test whether the pom-pom molecules could be used to kill drug-resistant bacteria on hospital doorknobs and other places where they commonly spread. They also hope to eventually test them in people with antibiotic-resistant bacterial infections.
Because the molecules can be selectively targeted towards individual types of drug-resistant bacteria, the hope is that they will preserve people’s healthy bacteria, says O’Brien-Simpson. “So, for example, if you were being treated for an MRSA infection, you wouldn’t have all your good gut microbes wiped out at the same time,” he says.
ACS Applied Materials & Interfaces
