A novel lytic bacteriophage BUCT791 effectively controls multidrug-resistant Klebsiella pneumoniae in vitro and in vivo.

Acute infections caused by multidrug-resistant (MDR) Klebsiella pneumoniae immediately necessitate the development of novel therapeutic strategies. Phage therapy offers a viable alternative for combating MDR Klebsiella infections. Here, we report the isolation and comprehensive characterization of a novel lytic bacteriophage, BUCT791, recovered from hospital sewage. Phage BUCT791 exhibited a short latent period (20 min), a large burst size (∼275 PFU/cell), rapid adsorption efficiency (>90% within 15 min), and remarkable stability across a wide range of temperatures (4-50 °C) and pH values (3-12). Whole-genome sequencing revealed a 48,388 bp double-stranded DNA genome with a GC content of 50%, encoding 74 predicted open reading frames (ORFs) and lacking any virulence or antibiotic resistance genes, confirming its biosafety for therapeutic applications. Phylogenetic analysis assigned phage BUCT791 to the genus Jedunavirus (family Myoviridae) and identified it as a member of the species Klebsiella virus FZ14. In vitro assays demonstrated that BUCT791 effectively inhibited Klebsiella growth within 2 h and significantly inhibited biofilms formation. In vivo, phage treatment markedly improved Galleria mellonella larval survival from 10% to 80%. Collectively, these findings indicate that BUCT791 possesses potent antibacterial activity and represents a promising candidate for developing safe and effective phage-based therapeutics against MDR Klebsiella pneumoniae infections. IMPORTANCE: This study reports the isolation and characterization of BUCT791, a novel lytic bacteriophage active against multidrug-resistant Klebsiella pneumoniae. BUCT791 showed strong stability, efficient bacterial killing, antibiofilm activity, and improved survival in an in vivo infection model, supporting its potential as a promising alternative strategy against MDR K. pneumoniae infections.