Characterization and genome analysis of novel Klebsiella pneumoniae phage vbKpUKJ_2 isolated from hospital sewage water.

Background: Multidrug-resistant (MDR) Klebsiella pneumoniae is a critical healthcare challenge due to its extensive resistance to antibiotics and role in causing severe infections. Bacteriophages offer a promising alternative for targeting MDR pathogens. This study characterizes a novel phage, vbKpUKJ_2, isolated from hospital sewage water, against clinical K. pneumoniae isolates.

Methods: Phage vbKpUKJ_2 was isolated and purified using the double agar overlay method. Host range and sensitivity were tested against 40 clinical K. pneumoniae isolates using growth inhibition assays. Morphological characterization was performed using transmission electron microscopy (TEM). Genomic analysis was conducted to evaluate the absence of antibiotic resistance genes and determine phylogenetic relationships. Stability assays assessed the phage's thermal and pH tolerance.

Results: Phage vbKpUKJ_2 demonstrated broad range activity against clinical K. pneumoniae isolates. TEM revealed it belongs to the Drexlerviridae family. Genomic analysis confirmed the absence of antibiotic resistance genes and identified conserved functional regions shared with related phages. vbKpUKJ_2 exhibited broad pH stability (pH 4-10) and thermal stability between 30 °C and 60 °C. The one-step growth curve indicated rapid lytic activity, with a burst size of 323 phage particles per cell.

Conclusions: vbKpUKJ_2 shows promising therapeutic potential against MDR K. pneumoniae. Its stability, absence of resistance genes, and rapid lytic cycle highlight its suitability for inclusion in phage therapy protocols, particularly as part of combination therapies targeting MDR infections.