• ECbfPdtta

Antibiotic-resistant bacterial infections pose a significant health challenge, with Escherichia coli (E. coli), a common gut bacterium, frequently causing healthcare-associated infections. E. coli strains can lead to gastrointestinal illness, urinary tract infections (UTIs), and systemic infections like sepsis and meningitis. Resistance develops through genetic mutations or gene transfer between bacteria, exacerbated by the misuse of antibiotics in medicine and agriculture. Phage therapy, using bacteriophages to target bacteria, is a promising alternative. This thesis aimed to isolate and characterize bacteriophages against E. coli, assessing their potential for environmental surveillance and therapeutic use. Phages were isolated from wastewater and soil, enriched, and identified by plaque morphology. After amplification, their genomes were sequenced using Illumina technology and analyzed for virulence or resistance genes. These phages were tested against over twenty clinical strains of antibiotic-resistant E. coli to evaluate their host range and effectiveness. Some phages showed broad-spectrum activity, beneficial for phage cocktail formulations. Phages were also tested with doxycycline, typically used for intracellular pathogens, on both planktonic and biofilm-embedded E. coli. The combined treatment's impact on biofilms was visualized using scanning electron microscopy (SEM).