Looming global crisis: Rising tide of antibiotic resistance

Scientists from Mass Eye and Ear and the Broad Institute of MIT and Harvard have made a significant leap in our understanding of antibiotic-resistant bacteria, specifically within the Enterococcus genus.

This research has uncovered 18 previously unknown species of enterococci, gut microbes prevalent in most land animals, and has identified hundreds of new genes.

These discoveries provide critical insights into the mechanisms of antibiotic resistance, a global health crisis that is projected to rival cancer as a leading cause of death by 2050.

Enterococci: Frontline antibiotic resistance foes

Enterococci are notorious for causing multidrug-resistant infections, especially in hospital settings post-surgery, posing lethal risks and imposing over $30 billion in additional healthcare costs annually.

This study, published in the Proceedings of the National Academy of Sciences (PNAS), expands the known diversity of enterococcal strains by more than 25% and suggests that insects and other invertebrates are major natural reservoirs for these bacteria, including naturally antibiotic-resistant species.

“Over the past 75 years, antibiotics have saved hundreds of millions of lives and have been pivotal in all types of surgery,” stated Michael S. Gilmore, PhD, Chief Scientific Officer at Mass Eye and Ear and director of the Infectious Disease Institute at Harvard Medical School.

Gilmore emphasized the crisis proportions reached by antibiotic resistance in recent decades, highlighting the urgent need for a deeper understanding of how resistance genes spread to hospital bacteria, threatening human health.

From soil to science: Origins of antibiotics

The origins of antibiotics trace back to the 1920s, with compounds like penicillin produced by soil microbes. These antibiotic-producing microbes, thriving in rotting plant matter, contribute to the distinct smell of forest soil.

The study led by Gilmore and Ashlee Earl, PhD, director of the Bacterial Genomics Group at Broad, involved an international team, including elite adventurers, collecting a diverse range of samples from remote global locations.

These efforts previously revealed that Enterococcus bacteria emerged approximately 425 million years ago, suggesting a long evolutionary battle with antibiotic resistance.

“Until recently, most of what we’ve understood about the genetics of enterococcus come from those that make us sick, and that’s a problem — like trying to understand darkness without ever seeing the light,” said Earl.

“Expanding our view to include those from outside of hospitals, with the help of citizen scientists, gave us the contrast we needed to identify how they make people sick in the hospital, and also gives the public the chance to co-own solutions,” she concluded.

Insects: The hidden allies of antibiotic resistance

This research posits that insects, by consuming rotting plant material laced with natural antibiotics, have played a significant role in the evolution of antibiotic resistance within gut bacteria like Enterococcus.

Such resistance predates human antibiotic use, dating back to when antibiotics were first introduced in the 1940s and ’50s, suggesting that these resistances were already embedded in the environment.

“The COVID-19 pandemic revealed that nature contains many infectious risks for humans,” Glimore reflected.

“This study shows that insects and their relatives in nature are a large and uncharacterized reservoir of undiscovered genes in microbes closely related to those that cause some of the most antibiotic resistant infections,” he concluded.

Through these findings, scientists are broadening our genetic database of enterococci and stepping closer to unraveling the complexities of antibiotic resistance.

This knowledge is crucial for developing strategies to combat one of the most pressing health threats of our time, offering hope for future breakthroughs in preventing and treating antibiotic-resistant infections.

The full study was published in the journal Proceedings of the National Academy of Sciences.

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