If someone told you that antibiotic resistance can emerge in your gut, even without taking antibiotics, you'd probably look at them skeptically. But it's true. Recent research from the UK's Earlham Institute and Quadram Institute, working with scientists from around the world, suggests that any and all of the bacteria and other microorganisms that set up home in and on human bodies may be a source of antibiotic resistance.
"Even a healthy individual, who hasn't taken antibiotics recently, is constantly bombarded by microbes from people or pets they interact with that can lead to resistance genes becoming embedded in their own microbiota," says microbial ecologist Chris Quince of Earlham and Quadram. "If they exist in a population with a heavy burden of antibiotic consumption, that leads to more resistance genes in their microbiome." And it's more than just those close to us who can affect our gut microbiome. "Our bodies are continually importing and exporting microbes and pathogen strains," Quince explains. "These strains are themselves passing genes back and forth, which means the challenge of AMR [antimicrobial resistance] has to be tackled at both the micro and macro level."
The gut microbiome is especially important, playing a part in digestion, immune system function, and more. It's thought that microbes living in the gut could be a significant contributor to antimicrobial resistance. The team analyzed over 3,000 gut microbiome samples from people in 14 different countries and found two distinct trends. They found two clusters, or resistome profiles, of antimicrobial resistance gene (ARG) types in the gut microbiome. They also found that ARG abundance and diversity varied based on the level of antibiotic consumption in that country, with prevalence increasing in countries where antibiotics are heavily used. "This study is so important because it can, for the first time, quantify the impact national antibiotic usage has on our commensal bacteria, as well as giving us insights into the common types of resistance," says microbial bioinformatician Falk Hildebrand.
So what does this mean for us? It means we need to be careful about our use of antibiotics, and we need to consider the wider problem to be tackled at both the individual and population level. It means being mindful of the bacteria and other microorganisms around us, and understanding the potential risks and benefits they pose. The human body is a complex ecosystem, and we need to be mindful of how we affect it.