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Antibiotic resistance is a growing concern for public health around the world, as it limits the effectiveness of antibiotics in treating infections caused by bacteria. While overuse of antibiotics in medicine and agriculture is thought to be a driving force behind the emergence and spread of antibiotic-resistant bacteria, it cannot fully explain the widespread distribution of antibiotic resistance genes in environments far removed from human activity.
A recent study published in eLife by Léa Pradier and Stéphanie Bedhomme of the University of Montpellier sheds new light on this matter. The researchers conducted one of the largest surveys of antibiotic resistance genes to date, analyzing over 160,000 bacterial genomes collected from all over the world. They focused on resistance against aminoglycoside, a widely used family of antibiotics, and 27 clusters of genes that code for aminoglycoside-modifying enzymes (AME genes).
The researchers found that the prevalence of genes for aminoglycoside resistance increased between the 1940s and the 1980s, following an increase in the use of antibiotics after the discovery of streptomycin in 1943. However, the prevalence remained at around 30% despite a decrease in consumption. They also found that 40% of the resistance genes were potentially mobile, which means they can be easily exchanged between bacteria.
The study also revealed that antibiotic-resistant bacteria are present in most biomes, not just in hospitals and farms. The prevalence of aminoglycoside resistance genes varied more from biome to biome than it did with human geography or with the quantity of antibiotics used. This suggests that the antibiotic resistance found in humans in one country is more likely related to the antibiotic resistance found in humans in a distant country than it is to the antibiotic resistance found in the soil or animals nearby. Furthermore, biomes such as soil and wastewater likely play a key role in spreading the genes for antibiotic resistance across different biomes.
These findings raise important questions about the mechanisms underlying the spread of antibiotic resistance. What factors promote the spread of antibiotic resistance in environments not impacted by human activities? Can we extrapolate these results from the aminoglycosides to all other classes of antibiotics? Is it possible that antibiotic resistance results from interactions with local microbial communities more than exposure to commercial antibiotics? Do the genes for antibiotic resistance spread in the pathogenic bacteria responsible for human and animal infections in the same way as they spread in non-pathogenic bacteria? Given the extent of the selective pressure exerted by human pollution, what limits the spread of antibiotic-resistance genes between biomes, especially given the large proportion of genes on mobile elements?
While consumption still plays a significant role in resistance to antibiotics used to treat infections, particularly in humans and clinical biomes, it is clear that we need to pay more attention to the role of the environment in combatting antibiotic resistance on a global scale. This study emphasizes the importance of considering the role of non-human environments in the spread of antibiotic resistance and the need for further research to better understand the mechanisms underlying this phenomenon. By doing so, we can develop more effective strategies to combat antibiotic resistance and preserve the effectiveness of antibiotics for future generations.
WORDS: Scientific Inquirer Staff.
IMAGE CREDIT: Helena Lopes.