ETD

• escherichia coli
• phage therapy
• UTI

The main aim of the project was to develop a phage cocktail to treat urinary tract infections due to MDR E. coli.
In the first part of the work, bacteriophages active against E. coli strains were characterized both genotypically and phenotypically to assess their biological properties and lytic activity. Particular attention was given to whole-genome sequencing analysis in order to exclude the presence of undesirable genetic elements, such as virulence factors, toxin-encoding genes, lysogeny-associated genes, or antibiotic resistance determinants that could potentially be horizontally transferred. This step was essential to evaluate the biosafety profile of the selected phages and determine their suitability for therapeutic application. The host range of these phages was evaluated using a panel of clinical strains isolated from patients with UTIs. Based on the efficiency of plating results, one strain (E. coli PTV4) emerged as being susceptible to multiple phages.The second part of the thesis focused on investigating the activity of a phage cocktail targeting E. coli. In particular, phages were properly selected and combined into a cocktail. Then, its in vitro efficacy versus both planktonic cultures and biofilm-embedded bacteria as well as its stability under in vitro conditions mimicking both the physiological and pathological urinary pH environment (pH 3-7) have been evaluated.
In order to move progressively closer to a pathological model, the stability of the cocktail in vitro using urine samples from both healthy donors and UTI patients was evaluated. Finally, its ability to control bacterial growth was evaluated in urine samples, providing a more relevant assessment of its efficacy.