Characterization of broad host range bacteriophages vKpIN31 and vKpIN32 against hospital-acquired Klebsiella pneumoniae in Dakar, Senegal

Klebsiella pneumoniae, a common gut colonizer, has become a major opportunistic pathogen, especially with the rise of multidrug-resistant (MDR) strains. This study aimed to characterize two lytic bacteriophages against MDR K. pneumoniae strains isolated from hospital associated infections in Senegal. Among 28 MDR K. pneumoniae strains tested, phage vKpIN31 effectively lyse 15 strains encompassing 12 distinct K locus types. While phage vKpIN32 lysed 12 strains with 9 different K locus types, demonstrating broad host range activity. The isolated phages exhibited thermal and pH stability. One-step growth analysis revealed a latent period of 25 and 20 min and burst sizes of 281 and 246 PFU/cell for vKpIN31 and vKpIN32 respectively. The in vitro lytic activity of phages vKpIN31 and vKpIN32 at different multiplicity of infection (1, 10^-1, and 10^-3) revealed variable lysis efficacy against three K. pneumoniae strains (KP6, KP7, and KP17), with the highest effectiveness observed at an MOI of 10^-3 for both phages. Combination of both phages as cocktail led to improved efficacy against the targeted strains Also, both phages significantly reduced biofilm levels, from 18.6% to 67.9% for 24-hour mature biofilms and from 18.1% to 58.7% for 48-hour mature biofilms. Genomic analysis identified both phages as linear dsDNA viruses belonging to the Caudoviricetes class, and Sugarlandvirus sugarland species. No genes associated with a temperate life cycle, integrases, transposable elements, antibiotic resistance, or bacterial virulence were detected in their genomes. These findings highlight vKpIN31 and vKpIN32 as promising candidates for phage therapy. Additionally, their potential extends to serving as sources for antibacterial and antibiofilm agents, signifying their clinical relevance and therapeutic potential.