A CRISPR-armed phage clears a drug-resistant infection in one patient

Clinicians at the University of California San Diego treated a kidney transplant recipient with progressive malakoplakia caused by multidrug-resistant Escherichia coli, using SNIPR001 — a cocktail of bacteriophages carrying CRISPR machinery aimed at E. coli — as an add-on to prolonged antibiotics, ascorbic acid and bethanechol. The phage was given intravenously, topically and directly into the lesions under a single-patient emergency investigational new drug application. The case report appeared in Clinical Infectious Diseases on 11 August 2026 (DOI 10.1093/cid/ciag446).

The intra-abdominal mass measured 745 cm3 at baseline and 82 cm3 at one year, an 89% reduction. Skin lesions resolved, follow-up urine and tissue cultures were negative, and no phage-related adverse events were recorded.

Malakoplakia is rare, and its difficulty is that the bacteria persist inside host cells where most antibiotics reach poorly. That is also why the case matters beyond this diagnosis: it is the first report of a genetically engineered phage used against an intracellular infection in a person.

This is one patient, treated compassionately, with no control arm and no randomisation. It establishes that the approach can be delivered and tolerated, not that it works.