Isolation, characterization, and therapeutic assessment of novel phage vB_LSKP32 targeting KL64-type carbapenem-resistant Klebsiella pneumoniae.

The increasing prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) constitutes a substantial hazard to human health. Phage therapy represents a promising alternative for treating CRKP infections. This research isolated a novel phage, vB_LSKP32, which targets the KL64 capsular type of CRKP from hospital sewage samples. The phage vB_LSKP32 adsorbs rapidly to host cells, features a 5–10 min latent period, and yields approximately 56 ± 3 new phage particles per infected cell. It remains stable and infectious under conditions ranging from 4 °C to 50 °C and pH 4 to 11. The phage vB_LSKP32 genome contains a 40,942 bp linear dsDNA with a GC content of 52.92%. Genome annotation predicted 50 ORFs, with no evidence of antibiotic resistance genes, virulence genes, lysogeny-related genes and tRNA. Through intergenomic similarity studies and phylogenetic analyses, vB_LSKP32 was classified as a novel species within the genus Przondovirus, family Autographiviridae. Phage vB_LSKP32 exhibited efficient suppression of host bacterial proliferation for approximately 7 h in vitro. Moreover, it significantly enhanced the survival rate of Galleria mellonella larvae post-infection, with the survival rate positively correlating with phage titer. Notably, larvae treated at an MOI of 100 elevated the survival rate to 90% (vs. 15% in controls). Our findings suggest that phage vB_LSKP32 shows significant potential as an antimicrobial agent against KL64-type CRKP.