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.

vB-Ea-5: a lytic bacteriophage against multi-drug-resistant Enterobacter aerogenes.

BACKGROUND AND OBJECTIVES: Multi-drug-resistant Enterobacter aerogenes is associated with various infectious diseases that cannot be easily treated by antibiotics. However, bacteriophages have potential therapeutic applications in the control of multi-drug-resistant bacteria. In this study, we aimed to isolate and characterize of a lytic bacteriophage that can lyse specifically the multi-drug-resistant (MDR) E. aerogenes. MATERIALS AND METHODS: Lytic bacteriophage was isolated from Qaem hospital wastewater and characterized morphologically and genetically. Next-generation sequencing was used to complete genome analysis of the isolated bacteriophage. RESULTS: Based on the transmission electron microscopy feature, the isolated bacteriophage (vB-Ea-5) belongs to the family Myoviridae. vB-Ea-5 had a latent period of 25 minutes, a burst size of 13 PFU/ml, and a burst time of 40 min. Genome sequencing revealed that vB-Ea-5 has a 135324 bp genome with 41.41% GC content. The vB-Ea-5 genome codes 212 ORFs 90 of which were categorized into several functional classes such as DNA replication and modification, transcriptional regulation, packaging, structural proteins, and a host lysis protein (Holin). No antibiotic resistance and toxin genes were detected in the genome. SDS-PAGE of vB-Ea-5 proteins exhibited three major and four minor bands with a molecular weight ranging from 18 to 50 kD. CONCLUSION: Our study suggests vB-Ea-5 as a potential candidate for phage therapy against MDR E. aerogenes infections.