Potential of Klebsiella pneumoniae Phage Depolymerases as Antimicrobial Agents.

Taylor, Christian Frederic (2020) Potential of Klebsiella pneumoniae Phage Depolymerases as Antimicrobial Agents. Masters by Research thesis (MSc), Manchester Metropolitan University for the degree of Master of Science (by Research).

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Abstract

Klebsiella pneumoniae is a pathogenic Gram-negative bacterium which is prevalent in hospitals and infects immune-compromised individuals. It primarily causes pneumonia but also infects the urinary system and the liver. Due to overuse and misuse of antibiotics, multidrug resistant strains have arisen that threaten the effectiveness of last-line antibiotics. One of the most prevalent being sequence type (ST)258 strains which mainly impacts Europe and North America. Bacteriophage (phage) are viruses that infect bacteria and are currently under scrutiny as antimicrobial agents to increase the efficacy of antibiotics against resistant pathogens or take over entirely against those that no longer can be treated by antibiotics. They produce depolymerase enzymes to hydrolyse the capsular polysaccharide of the bacterium allowing the phage to contact the bacterial cell surface. In this study seven phage which infect ST258 have been isolated and eight putative depolymerase genes identified. The aim of this study is the expression of these proteins and the characterizing and comparison of their efficacy at treating four K. pneumoniae isolates. One ‘high’ and one ‘low’ biofilm producer from each group, of the serotypes KL106 and KL107 within the multi locus sequence type (MSLT) group ST258 and comparison of the depolymerases to the whole virion. The production and isolation of these depolymerases was not achieved in this study, but the efficacy of the whole virion was tested in both planktonic and biofilm assays. KP5 was the only 8 phage to show the ability to reduce biofilm growth in its host after 24h and to infect all hosts in the planktonic assay. Future work should include the production and characterization of the depolymerase enzymes. Then the most appropriate could be used in a cocktail or in conjunction with antibiotics and tested in vitro and in vivo.