Characterization of bacteriophages against uropathogenic Klebsiella pneumoniae

Urinary tract infections (UTIs) affect approximately 150 million people globally each year. Complicated UTIs are particularly challenging to treat due to the presence of multidrug-resistant pathogens. Gram-negative bacilli, including Klebsiella pneumoniae, are the leading cause and can resist commonly used antibiotics. Thus, alternative non-antibiotic treatments are urgently needed, and bacteriophages (phages) represent a promising option. This study aims to isolate, characterize and evaluate phages with therapeutic potential against uropathogenic K. pneumoniae. Of the 19 phages isolated from wastewater sources in Belgium, six were selected for further assessment based on their host range. In vitro bactericidal activity was evaluated using time-kill assays, which demonstrated a significant reduction in bacterial growth following phage treatment. Stability in artificial urine and antibiofilm activity, evaluated using the crystal violet method, were also assessed. Phage stability over 24 hours in artificial urine showed no significant loss in phage activity in five of the six phages evaluated. Compared to the control, phage-treated samples showed inhibited biofilm formation and disruption of mature biofilms. However, this effect depended on both bacterial strain and phage dose. These findings support the development of phage-based therapies against antibiotic-resistant bacteria.