Browsing by Author "Nylund, Tiina"

The resilient nature of enterococci has made once a harmless commensal bacterium into a significant nosocomial pathogen. The increasing antibiotic resistance among Enterococcus faecalis and Enterococcus faecium has created pressure to find alternative therapies to traditional antibiotics. Phage therapy that utilizes virulent bacteriophages has been seen as a promising alternative to treat enterococcal infections due to their intrinsic specificity and ability to eradicate bacterial biofilm. In this thesis, therapeutic potential and limitations of previously isolated Enterococcus phages were further assessed. Genome analysis of the Enterococcus hosts revealed the presence of prophage regions, antibiotic and toxin resistance genes, and pathogenicity-related genes associated with invasion and intracellular resistance in the host genomes. Despite the presence of prophages and antibiotic-resistance genes, no concerning findings were made suggesting the potential suitability of Enterococcus hosts for phage propagation. Evaluation of phages against preformed (1-day-old) Enterococcus biofilms yielded diverse results, as some phages demonstrated high efficacy in biofilm elimination and prevention, while others were less effective. Additionally, experiments on phage-antibiotic interactions unveiled synergistic effects and promising potential in preventing the emergence of phage and/or antibiotic resistance. Furthermore, the impact of phage resistance on phage adsorption and susceptibility to other phages used in this study was examined, revealing varying mechanisms bacteria employ to evade phage infection. Understanding the intricate interplay between phages and bacterial hosts can enhance targeted therapeutic strategies by potentially refining the design of phage cocktails or phage-antibiotic combinations, thereby providing more effective treatment options against challenging enterococcal infections. Furthermore, as the demand for alternative treatment options in clinical settings grows, ongoing investigation is crucial to ensure the successful integration of therapeutic phages into medical practice.