Bacteria producing the drug that will destroy bacteria
S. aureus is ubiquitous, carried by 30% of adults, but becomes dangerous when it penetrates skin barriers, causing pneumonia, bone infections, and implant-related infections resistant to antibiotics. Scientists engineered artificial phages carrying CRISPR 'scissors' that infiltrate bacteria and activate dormant viral genes, offering personalized medicine potential by targeting specific bacterial strains.
- Staphylococcus aureus kills approximately one million people annually worldwide
- In Navarre, about 60 of 1,500 annual prosthetic implants become infected by the bacterium
- Biofilms formed by the bacteria on implants make them up to 1,000 times more resistant to antibiotics
- The engineered phages carry CRISPR gene-editing technology to cut bacterial DNA at precise locations
- Three in ten adults carry the bacterium harmlessly on their skin
Navarrabiomed researchers are using genetically modified viruses as a Trojan horse strategy to combat antibiotic-resistant Staphylococcus aureus, incorporating CRISPR technology to destroy the dangerous bacteria that causes approximately one million deaths annually.
Staphylococcus aureus lives on the skin of roughly three in ten adults without causing harm. It is everywhere, unremarkable, part of the body's ordinary microbial landscape. But when this bacterium breaches the skin's protective barrier, it becomes something else entirely—a pathogen capable of triggering pneumonia, bone infections, heart valve disease, and abscesses. It kills about a million people annually worldwide, and it has become nearly impossible to kill with conventional antibiotics.
The World Health Organization lists it among the planet's most serious public health threats, not because it is uniquely lethal, but because it has learned to evade the drugs designed to destroy it. In the Spanish region of Navarre, researchers at Navarrabiomed—a biomedical research center run jointly by the regional government and the public university—have begun pursuing an unconventional strategy. They are engineering viruses to act as Trojan horses, infiltrating the bacteria and deploying genetic scissors to cut it apart from within.
The problem is especially acute when Staphylococcus aureus encounters medical implants. Each year, Navarre surgeons place roughly 1,500 prosthetics—knee replacements, hip replacements, hernia meshes, catheters. About four percent of these, around 60 annually, become infected by the bacterium. Once attached to the implant's surface, the bacteria form a biofilm, a protective film that makes them up to 1,000 times more resistant to antibiotics and immune system attack. These infections rarely resolve cleanly. Most require the implant to be removed and replaced. Some strains of the bacterium, in certain countries as many as half, resist most available antibiotics. The options for treatment shrink to almost nothing.
The Navarrabiomed team, led by researcher Íñigo Lasa and doctoral candidate Nahiara Garmendia-Antoñana, drew inspiration from a 2018 article in Nature Biotechnology describing dormant viral fragments embedded in the bacterium's own genome—ancient invaders that had lost the ability to reproduce. The scientists asked a simple question: what if they could reactivate these defective viruses? What if they could give them new tools?
They designed artificial viruses—phages that do not exist in nature—carrying the CRISPR gene-editing system. These engineered viruses function as delivery vehicles, smuggling molecular scissors into the bacterium's interior. The scissors are programmed to cut the bacterial genome at precise locations, destroying it from within. The construction is intricate laboratory work: assembling seven separate genetic components—the CRISPR system itself, regulatory elements, a guide RNA that directs the scissors to their target—and packaging them inside a viral shell. The researchers then introduce this engineered phage into a laboratory strain of Staphylococcus aureus, which becomes the factory that manufactures the weapon against itself. It is paradoxical: bacteria producing the drug that will destroy bacteria.
Phage therapy is not new. Scientists discovered bacteriophages in 1915, and within two years a Canadian researcher named Félix d'Herelle proposed using them as medicine. But phages have a fundamental limitation: they are extraordinarily specific. A single phage might attack only one variant of a bacterial species while leaving others untouched. This specificity made it difficult to develop a single treatment effective against all strains of a pathogen. When antibiotics arrived, research shifted almost entirely toward them—except in the Soviet Union, where phage therapy continued. Now, as antibiotic resistance spreads, scientists are returning to an old idea.
Lasa emphasizes that the scale of the problem remains underappreciated. Antibiotic resistance threatens not just infection treatment but the entire foundation of modern medicine. Transplants depend on antibiotics to prevent infection in immunocompromised recipients. Chemotherapy depends on them. Surgery depends on them. Implants depend on them. If bacteria become resistant enough, these procedures become too dangerous to perform. The bacterium's resistance emerges through natural selection: a mutation grants immunity to a drug, and suddenly that strain flourishes while its competitors die. Antibiotic overuse accelerates this process, creating conditions where resistant bacteria thrive. The specificity that once made phage therapy impractical may now be its greatest strength. If doctors know which bacterial strain they are fighting, they can engineer a phage tailored to attack it—true personalized medicine, adapted to the individual patient's infection. The research, funded by Spain's Ministry of Science, Innovation and Universities, has been published in npj Biofilms and Microbiomes. It represents one path forward as the antibiotics that transformed medicine in the twentieth century lose their power.
Citas Notables
Conceptually, the phages would be an extraordinary drug, but we are not fully aware of the magnitude of the problem with antibiotic resistance.— Íñigo Lasa, lead researcher at Navarrabiomed
If a phage infects bacteria, it only attacks one variant—like a virus that recognizes only someone wearing glasses, or only someone who is bald, or only someone with long hair.— Íñigo Lasa, explaining phage specificity
La Conversación del Hearth Otra perspectiva de la historia
Why does this bacterium resist antibiotics so effectively when others don't?
It's partly luck, partly evolution. Staphylococcus aureus is exceptionally good at adapting to its environment and producing compounds that help it evade immune attack. But the real resistance comes from mutations—random changes in its DNA that happen to make it immune to a drug. Once that mutation exists, antibiotics actually help it spread, because they kill all the competing bacteria around it.
So the virus approach is fundamentally different?
Completely. Instead of poisoning the bacterium, you're using a virus to infiltrate it and cut its genome apart with precision. The virus gets inside the cell's defenses in a way antibiotics cannot.
But you mentioned the phages are extremely specific. How is that useful if you need to treat many different strains?
That's the insight. Specificity is only a problem if you're trying to make one pill for everyone. But if you know which strain is infecting a particular patient—and modern diagnostics can tell you that—you engineer a phage to match it exactly. It becomes medicine tailored to that person's infection.
What happens to the implant itself? Does the phage damage it?
No. The phage only targets the bacterial cells. The implant is just metal or plastic. Once the bacteria are gone, the implant can stay in place.
Why haven't we been using phages all along?
We were, in some places. But when antibiotics arrived in the mid-twentieth century, they seemed like a miracle—one drug that worked against many bacteria. Everyone abandoned phages except the Soviets. Now we're circling back because the miracle is failing.
What's the timeline before this becomes a treatment people can actually receive?
That's the hard part. The research is published, the concept works in the lab. But moving from laboratory to clinic takes years of safety testing, regulatory approval, clinical trials. This is foundational work, not yet a finished medicine.