One fact: antibiotic resistance could kill more than 39 million people directly and 169 million indirectly worldwide in the next quarter of a century, according to a projection published in The Lancet just a month ago. It is not surprising, then, that microbial resistance is one of the main issues of concern for medicine. And the solution to this problem could be waiting to be discovered on your toothbrush.
The bathrooms are colonized by an invisible fauna. They are families of viruses and bacteria that number in the millions, and about which science still does not know enough. But there is no need to be alarmed: these microscopic biological entities can be great allies for humans. At least some of them. A new study published this Wednesday in the magazine Frontiers in Microbiomes who analyzed shower heads and toothbrushes in dozens of American bathrooms found such a diverse collection of viruses, most had never been identified before. Viruses with a unique ability to destroy bacteria.
Humans spend 93% of their time in self-constructed environments such as homes and offices. Spending so much time in these environments has led to the development of complex and very particular microbiomes – sets of bacteria, viruses, fungi and other organisms. These microscopic universes are shaped by human interaction and other environmental factors. However, most of the scientific efforts to study and understand them have been centered around bacteria, leaving viruses in the background. Although not for Erica Hartmann, an indoor microbiologist and professor at Northwestern University. The scientist has dedicated much of her career to trying to understand and identify viruses that proliferate in artificial environments.
In his latest research, Hartmann has found thousands of viruses about which very little is known. “It is surprising how much untapped biodiversity there is around us. And you don’t even have to go far to find it: it’s right under our noses,” he says. Then he adds: “When analyzing the samples, we found many things that seemed new and unknown. Although I don’t think it’s something specific to toothbrushes or showers. “If we had taken hundreds of samples from any random place, we would have found many viruses that we know very little about.”
In this case, to identify the viruses, Hartmann and his team collected 92 samples of microorganism communities attached to the surface of shower heads and 34 samples taken from toothbrushes throughout the United States. They then took the collections to the lab and used DNA sequencing to examine them. The results showed that the samples had more than 600 different viruses and no two models were the same. “Each shower head and toothbrush is like a little island in itself. If we also had brushes from Spain or any other part of the world, they would probably all have new viruses. So I would say that the only thing we can generalize from these results is that there are new things everywhere you look,” he explains.
What the scientist was looking for were bacteriophages or phages, a type of virus that coexists with bacteria and can be their best allies or their worst enemies. And he found them.
María del Mar Tomás, head of the Translational and Multidisciplinary Microbiology group at the Biomedical Research Institute of A Coruña, also knows phages well. He has been working with them for years. “They are so abundant that it is believed that for each bacteria there may be at least 10 viruses that coexist with it,” says the researcher.
Until now, science has identified two types of phage viruses. There are those that enter the interior of the bacteria and coexist with it—they can even provide proteins to strengthen it—called lysogenic phages, and then there are lytic phages, which would be something like bacteria destroyers.
Science needs to know both types of viruses if it wants to win the fight against microbial resistance. You need lysogenic phages because resistance to antibiotics is often produced by proteins that the virus provides to the bacteria to make it more robust, and lytic phages to understand their predatory mechanisms that manage to destroy the bacteria and thus be able to replicate them in favor of human health.
“In short,” explains Tomás, “knowledge of this virus-bacteria correlation is extremely important to obtain new therapeutic targets, new treatments and biotechnological applications based on this knowledge.” Hartmann elaborates on this: “Phage therapy has been around for over a hundred years, but we still don’t really understand why it sometimes works and sometimes doesn’t. “And part of that is because there is an incredible amount of diversity of interactions between phages and bacteria.” All the efforts put into advancing the understanding of how these interactions work will help scientists design better drugs in the future.
On the hunt for mycobacteriophages
Although they found few repeat patterns across all samples, Hartmann and his team noticed more mycobacteriophages than other types of phages. Mycobacteriophages infect mycobacteria, a pathogenic species that causes diseases such as leprosy, tuberculosis, and chronic lung infections. Hartmann hopes that, one day, researchers will be able to take advantage of mycobacteriophages to treat these and other infections that are already causing problems today. “We want to look at all the functions these viruses could have and figure out how we can use them,” he says.
Tomás assures that in the last three years the knowledge built around phages has been exponential thanks to massive sequencing techniques such as those used in Hartmann’s study. “We are going to be increasingly successful in developing treatments that have potential against antibiotic-resistant bacteria. We will even be able to recover certain antibiotics,” says Tomás.
However, this may not be the only solution. Phages should be added to early diagnosis, synergistic treatments and antibiotics. Tomás details it: “This is hope in the face of the antimicrobial crisis and it is a line of research with a lot of potential because phages are considered a medicine, so it is likely that they will provide good news in the coming years. But we cannot lose antibiotics.”
It’s time, says Hartmann, to give microbes some good press. “Very few bacteria actually make you sick. Many of them do very good things for us. They help us digest our food or put oxygen into the atmosphere. “If you approach the microbes around us with a sense of wonder and curiosity, you can understand how incredible these creatures are.”
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