Rational design of a hospital-specific phage cocktail to treat Enterobacter cloacae complex infections.

The Alfred Hospital in Melbourne, Australia, has reported an ongoing outbreak of infections caused by multidrug-resistant Enterobacter cloacae complex (ECC). Phage therapy is a promising strategy to treat antimicrobial-resistant infections. Utilizing the hospital's isolate collection, built over the past decade, we established an initial 3-phage cocktail with 54% ECC coverage. We then iteratively improved this product by enhancing phage killing efficiency using phage adaptation and expanded host range through targeted phage isolation against low-coverage ECC isolates. This optimization yielded Entelli-02, containing five well-characterized virulent phages that target clinical ECC isolates via distinct bacterial cell surface receptors. Entelli-02 exhibits 88% host coverage against The Alfred Hospital's ECC isolate collection (n = 206), confirmed by plaque formation and reduced bacterial load in septicaemic mice by >99%. We produced this cocktail as a therapeutic-grade product, ready for clinical use. Entelli-02 represents a hospital-specific phage cocktail with frontline efficacy and on-demand availability.