Recent progress in phage genetic engineering enables deliberate modifications of natural phage isolates to make them more suitable for therapeutic applications by modifying their host specificity and/or improving other properties on demand.

Panels of genetically engineered phages with improved therapeutic properties, increased safety and differentiated specificity, based on the genomic scaffolds of selected well characterized phage isolates, and the ability to acquire them rapidly at a relatively low cost may soon lead to therapeutic applications.

Progress in the understanding of the phage–bacteria interactions in the human/animal microbiome and their influence on health opens up possibilities for the application of genetically engineered phages to modify the microbiome composition and thereby attenuate symptoms of certain bacterial diseases as well as selected metabolic, mental, or immune disorders.