Isolating and sequencing vB_Kpn_3, a lytic bacteriophage against multidrug-resistant Klebsiella pneumoniae.

Aim: Phage therapy, as an effective and specific method in the treatment of multidrug-resistant (MDR) bacterial infections, has attracted the attention of many researchers. Methods and results: In this study, a double-stranded DNA phage with the ability of lysing some strains of MDR Klebsiella pneumoniae (vB_Kpn_3) was isolated from hospitals' wastewater and then characterized morphologically and genetically. Transmission electron microscopy and genetic analyses have revealed that vB_Kpn_3 is a member of Siphoviridae family. One-step growth curve also showed a burst time of 35 min and a burst size of 31 PFU/ml. The genome of the phage is composed of 112,080 bp with 41.33% G + C content carrying 186 open reading frames. Conclusion: vB_Kpn_3 is a broad host range phage that infects MDR K. pneumoniae and some other species of Enterobacteriaceae such as Escherichia coli and Salmonella typhi. In addition, no antibiotic resistance and toxin genes were detected in its genome.