Browsing by Author "Mustonen, Markus"

The increase of antibiotic resistance is one of the major healthcare threats globally. One potential way to battle against antibiotic resistant bacterial infections is to treat them with the natural opponents of bacteria, bacteriophages, known as phage therapy. The aim of this thesis was to identify new bacteriophages against clinically notable bacterial species such as Escherichia coli, Burkholderia cepacia, Enterococcus faecalis and Enterococcus faecium. Bacteriophages were screened from various origins such as hospital sewage samples, soil samples and manure samples, collected in between 2019 and 2022. The isolated bacteriophages were then initially characterized to evaluate their potential use in phage therapy. In this thesis, two phages (fHo-Eco16, fHo-Eco17) against clinical E. coli isolate and one phage (fHo-Efa06) against clinical E. faecalis isolate were found from the recently collected Finnish hospital sewage sample pool. Both E. coli phages were classified as Felixounaviruses belonging to family of Ounavirinae and class of Caudoviricetes. Enterococcus phage fHo-Efa06 was characterized as Saphexavirus belonging to class of Caudoviricetes. Preliminary genome annotation did not reveal any characteristics of lysogenic lifecycle, or antibiotic resistance or bacterial toxin genes, which would prevent the use of phages in phage therapy. Both E. coli phages (fHo-Eco16, fHo-Eco17) showed narrow host range infecting only the primary host bacterial isolate but none of 29 other tested clinical E. coli isolates. Phage fHo-Efa06 showed relatively broad host range properties infecting nine tested E. faecalis isolates out of 20 tested E. faecalis isolates but no infection capabilities against six tested clinical E. faecium isolates. In conclusion, freshly collected hospital sewage seemed to be optimal environment to find bacteriophages against clinical bacterial isolates. Furthermore, phages fHo-Eco16, fHo-Eco17 and fHo-Efa06 did not display any strictly unsuitable properties which could prevent their use in phage therapy. In turn, to obtain the definitive certainty on the usability of the phages in therapeutic use, in-depth host range screening together with detailed functional and structural annotation for the phage genomes of fHo-Efa06, fHo-Eco16 and fHo-Eco17 should be completed.