A 65-year-old man with a severe antibiotic-resistant E. coli infection saw dramatic improvement after receiving experimental phage therapy armed with CRISPR systems.
By Adam Makins · 
A 65-year-old kidney transplant patient has made a remarkable recovery from a severe antibiotic-resistant infection thanks to an experimental treatment involving bacteria-killing viruses equipped with CRISPR gene-editing technology. The case represents a promising breakthrough in fighting drug-resistant infections at a time when conventional antibiotics are losing their effectiveness.
The patient developed a serious infection caused by antibiotic-resistant Escherichia coli months after his transplant. The infection was devastating, creating a large mass on his bladder and causing open wounds across his abdomen. Despite aggressive treatment with conventional antibiotics and other standard therapies, nothing worked. His doctors at a California hospital made a bold decision: try an experimental phage therapy developed by the Danish company SNIPR.
Within just one week of starting the treatment, the results were striking. The open wounds began healing noticeably, and the bladder mass shrank to half its original size, from 0.74 litres down to 0.37 litres. It was the kind of improvement that seemed almost miraculous after months of conventional treatments had failed.
That said, the picture isn’t entirely clear-cut. The patient had been started on a new cocktail of more powerful antibiotics and other drugs about 11 days before beginning phage therapy. This timing raises an important question: was it the phages alone that worked, or did they work synergistically with the antibiotics? “It could be that the phages together with the antibiotics had this synergistic effect,” explains Eric van der Helm at SNIPR, one of the researchers who documented the case.
The synergy theory makes biological sense. Bacteria often form thick biofilms that are nearly impenetrable to antibiotic drugs. SNIPR’s previous research showed that CRISPR-armed viruses can break through these defenses and kill bacteria hiding within biofilms. By destroying the biofilm, phages might make antibiotics far more effective at reaching and eliminating the remaining bacteria.
Bacteriophages, viruses that target bacteria, are the most numerous biological entities on Earth, yet their medical use remains surprisingly rare. That’s largely because isolating phages capable of killing a specific bacterium is time-consuming and expensive. But SNIPR and other companies worldwide are changing this by engineering phages to be more powerful weapons.
The company equipped their phages with CRISPR systems, turning the bacteria’s own defense mechanism against them. CRISPR originally evolved in bacteria as protection against viruses, allowing bacteria to target and destroy specific viral DNA. Now, biologists have flipped the script: the viruses themselves carry CRISPR systems designed to chew up specific bacterial DNA.
SNIPR001, the company’s engineered phage cocktail, is designed to kill 90 percent of all E. coli strains. It’s versatile too. The treatment can be delivered orally to target E. coli in the gut, given intravenously, or applied directly to infected wounds, as it was for this patient.
While this single case is encouraging, it’s hardly definitive proof. “No firm conclusions can be drawn from a single case,” van der Helm cautions. “That’s why we’re keen to explore this further in clinical trials.” Still, the response has been immediate. SNIPR has already received 12 additional requests for compassionate use of the treatment.
A phase II trial is now underway in the United States to determine whether lowering E. coli levels in the gut with SNIPR001 can reduce the risk of E. coli blood infections in cancer patients receiving certain treatments. This represents a significant opportunity to test the phage therapy approach in a controlled clinical setting.
The implications extend beyond this single infection too. Antibiotic resistance is becoming a global crisis, and alternative approaches like phage therapy could be essential to combating infections that conventional medicines can no longer touch. As antibiotic-resistant bacteria spread and CRISPR-armed phages continue development, we’re witnessing what might be the beginning of a fundamental shift in how we treat bacterial infections. Will engineered viruses become our front line of defense against the superbugs of tomorrow?
