Sunday , June 20 2021

Bugs Vs. Superbugs: Insects offer a promise to combat antibiotic resistance



Nobody likes a roach in their house. But before you break the unwanted intruder, think about it: this six legs can one day save your life.

This is true. Insects, long known for the spread of diseases, can help with their treatment. Or rather, the microbes living inside them could. Scientists have discovered dozens of microorganisms living in or on insects that produce antimicrobial compounds, some of which may have the key to developing new antibiotic drugs.

They can not come too early. More infections become resistant to conventional antibiotics, and the pipeline of new antibiotics slows down.

"Search is growing [for antibiotics]and declining supply, "explains Jerry Wright, who heads the Institute of Infectious Diseases Michael G. DeGroo at McMaster University.

Most antibiotic drugs are found by bacteria living in the soil. But Cameron Curie, a professor of bacteriology at the University of Wisconsin-Madison, says soil demand for new antibiotics is becoming more and more meaningless.

"They continue to find already known antibiotics," Curie says. "There is a common opinion that wells with antibiotics from the soil … are dry.

Fortunately, there may be another well. Currie and a team of 28 researchers recently published a report in Nature Communications indicating that some of the bacteria living in insects are really good at killing germs that make people sick.

There are about 10 million species [of insect] "This means huge potential for many new ones [antibiotic] compounds. "

Microbe Fighters

Each insect contains an entire ecosystem of microorganisms, just like the microbial found in humans. There is also a quality that many of these insect microbes have in common, says Jonathan Klassen, Molecular and Cell Biology Assistant at the University of Connecticut and the author of the study.

They do not get along very well with each other.

And by not understanding, it means that they are constantly trying to kill each other through biochemical warfare. Many insect microorganisms make compounds that are toxic to other microbes – essentially, natural antibiotics.

Some of these natural antibiotics attract Curie's attention while he was a student examining leaf ants.

Ants with a leaf cutter are among the most fertile gardeners of nature. They do not actually eat the leaves they cut – instead they use them to cultivate a special type of fungus for food. However, it is not easy to be a fungus farmer.

"Like human farming, ants have disease problems," says Curie. "I found a specialized pathogen that attacked their garden.

Fortunately, the ants have a tool to deal with the problem. A type of bacteria living in ants exoskeleton produces a toxin that kills the pathogen. Like the pesticides used by a gardener, the toxin preserves the anthrax of the ants.

The discovery inspired Curie's curiosity. If ants can use these bacterial compounds to treat diseases in their fungi, can doctors use them to treat human diseases? If so, what other insects can also carry germs struggling with diseases?

To answer these questions, Kerry and his team spent years gathering thousands of insects, including cockroaches, from Alaska to Brazil.

"Every few months someone would go out to collect something," recalls Klasson, who at the time worked as a post-graduate student on the project.

The team investigates the bacteria from each insect to determine whether they can kill ordinary human pathogens, such as E. coli and resistant to methicillin Stafilococcus aureus (MRSA). They then compared the results of strains of insect bacteria with strains derived from plants and soil.

"We were really surprised [insect strains] were not as good, but apparently better in inhibition [pathogens]"says Kerry.

Testing a new antibiotic

Once a scientist has discovered that a strain of bacteria can kill microbes, the next step in drug development is to determine what bacterial compound is responsible for antimicrobial activity – as a chef looking for the secret ingredient in a particularly delicious soup.

Currie's team has found dozens of promising bacterial strains in insects. And anyone can bring a secret ingredient, which may be a new antibiotic compound.

This in itself was a great achievement. But the researchers went one step further. They isolate a compound from a particularly promising bacterial strain and show that it can inhibit fungal infections in mice, which is an important step in the development of the drug.

The composition, cyfomycin, is found on Brazilian ants that are involved in mushroom growing, close relatives of Curie ants, studied as a doctorate. Although this is far from becoming an approved drug, studies have shown that antibiotic compounds, new to science, can be insect-isolated.

Wright, an antibiotic investigator who did not participate in the study, says previous studies have shown that insect species contain antimicrobial compounds. But this is the first study that exhaustively shows that insects as a group are a promising source of new antimicrobials.

"No one has ever done anything on this scale," Wright explains.

Currie hopes one day cyfomicin may be approved for the treatment of yeast infections in humans. But before that happens, he has to undergo years of further testing.

"It [cyphomycin] is millions of miles [from approval]"This is the reality of the discovery of drugs."

However, Wright says researchers have already overcome one of the most difficult barriers to drug development by demonstrating that the compound is working in mice.

For Klassen, bets are too high to not try.

"Efforts like this study are crucial to keeping the pipeline running for antibiotics so the disease does not prevail," he says.

Ultimately, the consequences of a world without antibiotics are enough to make scientists look for new drugs in non-traditional places – even if that means watching a cockroach.

Paul Chisholm is a freelance writer in Rapid City, S.D. You can contact him on Twitter: @PaulJChisholm,

Copyright 2019 NPR. To see more, visit https://www.npr.org.


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