This Science Hot Topic is based on a between-issue update article by Liz Sheffield for Biological Sciences Review (March 2019). Subscribe to Biological Sciences Review now – from just £40.

What Are Superbugs?

Superbugs are bacteria that are resistant to antibiotics. The issue of antibiotic resistance is such a big issue in the NHS that Doctors often prescribe multiple antibiotics to combat a single infection.

It’s also linked to the topic of antimicrobial resistance, which describes this issue but when it relates to viruses, fungi and parasites as well as bacteria.

Superbugs Are Becoming More Common

Superbugs are becoming so common that they could lead to the deaths of 10 million people per year globally by 2050, according to a recent report commissioned by the UK government.

This estimate is based on the antibiotics currently approved for use to treat disease, most of which have been in service for more than 50 years. During that time, their use in humans and other animals has exerted selective pressure on bacterial populations, favouring the survival of those with genes conferring resistance.

After more than 30 years during which no new classes of antibiotics were discovered, 2015 saw one new class identified and 2018 saw at least two new breakthroughs in the fight against superbugs.

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Are Nano Superbugtraps The Future?

If harmful bacteria enter the bloodstream, they can multiply so rapidly as to cause life-threatening conditions including organ failure and sepsis.

There are two ways to treat infected patients. One is to administer antibiotics, the other is to pass their infected blood through a filter in a dialysis machine. This second method is the only option with antibiotic-resistant infections but has until now relied on carbon foam-based filters, which capture only 10% of the bacteria in the blood.

Now researchers in China, inspired by the Venus flytrap, have devised a claw-like filter that grabs 97% of the bacteria passing through. The claws of the filter are made from flexible polycrystalline nanowires tipped with concanavalin A. This protein binds to certain carbohydrates, including the sugars that coat the surface of bacteria such as Salmonella. The nanowires stick to and close over the bacteria, trapping them in a delicate cage and preventing them from reentering the patient’s bloodstream when the blood returns to the patient.

Discovering A New Antibiotic

Most of our best-known antibiotics were originally obtained from fungi or bacteria cultivated in laboratories. The most renowned example is penicillin, which was derived from a fungus. We know that there must be many more antimicrobial compounds produced by microorganisms in the natural environment, but finding conditions and media suitable for cultivating them has proved challenging.

Molecular biology techniques now allow researchers to avoid the need to cultivate organisms and go straight for the genes that carry the information necessary to make compounds of interest. A team in the USA recently extracted DNA from 2000 different soils, and used the polymerase chain reaction to amplify DNA sequences known to be associated with the production of bacterial-wall-busting compounds.

They found a sample from a desert region that fitted the bill. They cloned the relevant genes and rearranged them to insert into the host bacterium Streptomyces, which grows readily in the laboratory. The bacteria made a novel compound, which the researchers called malacidin (from Latin words for ‘killing’ the ‘bad’) and which works differently from any current antimicrobials.

It has already been used to clear infection from rats with the superbug methicillin-resistant Staphylococcus aureus (MRSA). Even better news is that after 20 days of continuous exposure, MRSA bacteria showed no signs of developing resistance to the new antibiotic.

Further Reading On Superbugs:

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