| Summary: | Objective To isolate a strain of lysing carbapenem-resistant Klebsiella pneumoniae phage, and explore its biological characteristics and whole genome information. Methods The phage was isolated and purified from waste water of the General Hospital of Western Theater Command Hospital by the double-layer agar plate method. The morphology of phage was observed by transmission electron microscopy, and its biological properties and in vitro antibacterial activity were determined. Whole-genome sequencing was used to analyze its structural characteristics, and a phylogenetic evolutionary tree and the comparative genomic analysis was conducted to analyze the evolutionary relationships of phage. Results A virulent phage was isolated and named vB_KpnP1, which formed a 2~3 mm transparent circular spot surrounded by a distinct halo; Electron microscopy showed that the head size of the phage was about 68.2 nm×64.3 nm, and the tail length was about 11 nm; The head of the phage was a regular icosahedron with a non-contractile short tail, which was thus identified as a member of the Autographiviridae family and the Caudovirales order; the optimal multiplicity of infection was 0.0 001, the incubation period was 10 min, the lysis period was 30 min, and the amount of lysis was 26 PFU/cell; The adsorption rate was about 80% in 10 min. The phage was insensitive to chloroform and was stable at temperatures of 10~50 ℃ and pH values of 4~12; The lysis rate of carbapenem-resistant Klebsiella pneumoniae was 54.55% (12/22), and the host spectrum was wide; In vitro antibacterial test showed that it could inhibit the growth of host bacteria. Phage vB_KpnP1 was double-stranded DNA (dsDNA) with a 40 352 bp of full genome length, and 53.09% of GC content. It contained 50 CDS. Conclusion A virulent Klebsiella pneumoniae phage, vB_KpnP1, with the potential to treat carbapenem-resistant Klebsiella pneumoniae infections, is successfully isolated.
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