That precision is the therapy's appeal and its difficulty: a phage that kills one strain may not work against another, so doctors must match the virus to the infection.
Doctors facing infections that no longer respond to antibiotics are turning to an unexpected ally: viruses that hunt and kill bacteria. According to a report in the Times of India, a Belgian-led research consortium has been testing personalised bacteriophage therapy, and the early results are encouraging enough to have prompted the first international clinical guidelines for the approach.
The study, published in 2024 in the journal Nature Microbiology, examined the first 100 consecutive cases treated through the consortium between January 2008 and April 2022. The cases came from 35 hospitals across 29 cities and 12 countries. According to the report, around 77.2% of infections showed clinical improvement after phage therapy, and the targeted bacteria were eliminated in 61.3% of cases. Many patients had already undergone conventional antibiotic treatment without sufficient success.
Phages are viruses that naturally infect bacteria. They attach to a bacterial cell, introduce their genetic material and use the cell's machinery to replicate, eventually breaking the cell open and releasing new viruses. Unlike many antibiotics, which affect several types of bacteria, phages tend to target particular species or even specific strains. That precision is the therapy's appeal and its difficulty: a phage that kills one strain may not work against another, so doctors must match the virus to the infection.
The report is careful to note the limits of the evidence. This was an observational study, not a controlled clinical trial, so it cannot establish that phage therapy alone was responsible for the improvements, nor how effective it would be across a larger group of patients. The researchers also found that bacterial elimination was less likely when phages were given without accompanying antibiotics, suggesting the two treatments may work together rather than as alternatives.
The new guidelines, led by the German Society for Infectious Diseases and published in Nature Medicine in September 2026, bring together 20 professional organisations, 18 international experts and two patient advocacy organisations. They contain more than 60 recommendations covering phage selection, laboratory testing, manufacture, administration and patient monitoring, alongside standards for quality control and documentation. The report stresses that every case should be recorded, since the treatment is still being studied.
Phage therapy is not yet a replacement for antibiotics, nor a routine treatment for everyday infections. It is being considered mainly for patients with particularly difficult infections, especially where conventional treatments have failed or cannot be used safely. Bacteria can develop resistance to phages too, and the human immune system may clear the viruses before they have time to work. What the guidelines and the Belgian data together suggest is that medicine may have another route against resistant infections, though one that still requires careful, case-by-case evidence before it can be judged at scale.
