The Genomic and Biological Characteristics of a Hypervirulent Klebsiella pneumoniae Bacteriophage

Objective In response to the serious challenge of antibiotic resistance posed by Klebsiella pneumoniae (Kp), this study aims to isolate and identify a hypervirulent Kp bacteriophage with potential clinical application value.Methods Using a hypervirulent Kp isolate as the host bacterium, we isolated and characterized a novel bacteriophage capable of lysing this strain. The genomic features, morphological characteristics, environmental stress tolerance, lysis efficiency, and host range were analyzed for the identified bacteriophage.Results Employing the hypervirulent Kp (hvKp) isolate QD22 as the host bacterium for phage isolation, the obtained phage PTF1 was found not only to lyse QD22 but also multiple other hvKp isolates, with 83.3% of the isolates lysed by PTF1 being hvKp isolates. Phage PTF1 belongs to the Podoviridae family and lacks virulence genes and antibiotic resistance genes. Biological characteristic analysis revealed that the optimal multiplicity of infection (MOI) for PTF1 is as low as 0.001, with a maximum burst size of 120 PFU/ cell. Even at an MOI as low as 10-6, PTF1 can completely inhibit the proliferation of the host bacterium. Environmental stress tolerance analysis indicated that PTF1 maintains high biological activity across a temperature range of 4-60°C and pH levels from 4 to 10.Conclusion Phage PTF1 is a novel short-tailed phage with high lytic efficiency, strong environmental stress tolerance, and a broad host range. Moreover, most of its susceptible hosts are hvKp isolates, indicating significant potential for clinical applications.