Consensus guideline from 20 societies sets 60+ recommendations for personalized phage therapy

A consensus guideline on personalized bacteriophage therapy has been published in Nature Medicine. It was developed within the methodological framework of the Association of the Scientific Medical Societies in Germany, led by the German Society for Infectious Diseases. The work involved 20 professional societies, patient advocacy groups and regulatory authorities, plus 18 international experts. The guideline contains more than 60 recommendations on core principles, infrastructure, preparation and quality control, administration and future research doi.orgNature Medicinedoi.orgOpen source ↗.

Phages are viruses that selectively infect bacteria. According to the authors, clinical use in many countries is held back by the lack of consensus on general principles, infrastructure requirements, quality-assured phage selection and preparation, administration, monitoring and documentation. Existing guidance, they say, lacks inspection-ready specifications for pharmacies and clinical sites doi.orgNature Medicinedoi.orgOpen source ↗.

Phage selection and quality control

Phages typically target particular bacterial species or even individual strains. A laboratory must therefore test whether a candidate phage kills the strain causing a patient's infection. This step, called a "phage match", should be completed as early as possible, because bacteria can change their susceptibility during an infection. If several pathogens are present, all relevant ones should be tested.

The guideline recommends that decisions involve the treating physicians, clinical microbiologists and recognized phage experts. It also sets expectations for cooperation among laboratories, phage manufacturers, pharmacies and clinical teams. Consistent testing methods and regular proficiency assessments are meant to make results from different sites comparable. Cases should be documented systematically and entered into registries.

Evidence and first clinical use

The guideline does not recommend phage therapy as a routine treatment. It may be considered when established treatments have failed, are unavailable or cannot be used safely. Properly manufactured and administered phages generally show a favorable safety profile, but controlled clinical trials have not yet shown how reliably the treatment works.

In a Belgian case series of 100 people who received phages, 77 percent showed clinical improvement. In 61 percent, tests no longer detected the targeted bacteria. Observational data of this kind cannot establish that phages caused the improvement.

Frankfurt University Medical Center reports that ten patients have been treated in its guideline-based program since February 2026. The pathogens include Pseudomonas aeruginosa and Staphylococcus aureus. Silvia Würstle, the guideline's corresponding author, said it gives physicians, pharmacists and regulators a common framework for introducing phage therapy.