Consensus Guideline Details Personalized Bacteriophage Therapy

A new consensus-based guideline provides more than 60 recommendations covering general principles, infrastructure, preparation and quality control, clinical administration, and future research priorities for personalized bacteriophage therapy, according to a consensus statement published in Nature Medicine.

Bacteriophages, or phages, are viruses that selectively infect bacteria and represent a potential option for treating difficult-to-treat bacterial infections amid rising antimicrobial resistance. The guideline was developed within the methodological framework of the Association of the Scientific Medical Societies in Germany (AWMF) under the leadership of the German Society for Infectious Diseases, involving 20 professional societies, patient advocacy groups, regulatory authorities, and 18 international experts. The authors noted that clinical implementation has been hindered by a lack of consensus on core principles, infrastructure requirements, quality-assured preparation, and administration and monitoring procedures.

Among the recommendations reaching strong consensus, the guideline states that an interdisciplinary discussion involving treating physicians, microbiologists, infectious disease specialists, and phage experts should precede phage therapy. Separately, the guideline states that the minimum requirement for physicians initiating treatment should be board certification. The authors also note that while safety data remain limited in infants, children, pregnant or breastfeeding patients, and immunocompromised patients, no data suggest safety issues in these populations, and treatment should be based on individual risk-benefit assessment. For dosing, the authors suggest a phage titer of 1×10^6 to 1×10^9 PFU/mL, adapted for expected phage loss depending on administration route.

The authors cited a case series of 100 patients treated in Belgium in which 77% showed clinical improvement and 61% achieved bacterial eradication, with no serious phage-related adverse reactions reported. The guideline's principal limitation, the authors wrote, is the scarcity of high-quality evidence, as the literature consists predominantly of preclinical and early-phase studies, expert opinion, and case reports; consequently, precise values for certain aspects, such as quality-control testing thresholds and dosing across administration routes, could not be specified.

Source: Würstle S, Lieberknecht-Jouy SC, Vehreschild MJGT, Classen AY, et al. A consensus-based guideline for personalized bacteriophage therapy. Nat Med. Published online September 21, 2026. doi:10.1038/s41591-026-04654-6