Engineering Bacteriophages to Combat Antimicrobial Resistance

Antimicrobial resistance poses a rising threat to global public health with 56,000 deaths every year across the UK, EU and USA attributed to infections caused by AMR bacteria. With few truly novel antibiotics being developed, alternative solutions have been sought to solve the increasing problem of antimicrobial resistance. Phages have long been considered a potential alternative to traditional antibiotics, and with recent advances in genetic engineering they could be improved upon even further to overcome some of their weaknesses.

The first part of this thesis focusses on engineering a phage to produce a genetic payload, specifically a colicin, in an attempt to enhance the killing ability of the phage. The so-called Murder Phages created here do indeed have enhanced virulence compared to their wild-type. Furthermore, the engineered phages display the ability to kill phage resistant bacteria in co-culture with phage susceptible hosts. Interestingly, however, bacteria appear to develop resistance faster when challenged with the engineered Murder Phages.

The second part of this study focusses on evaluating current and novel methods to engineer phages. While little success was achieved here using CRISPR systems to select against wild-type phages, a new method of identifying engineered phage by utilising lacZα as a genetic marker to turn plaques blue is explored.

The results within this thesis show promising proof-of-concepts that could now be developed further to enable phages to be engineered more efficiently and in ways that could improve their efficacy as therapeutics.