Fatemeh Zeynali Kelishomi - Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
Farhad Nikkhahi - Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran

Background and Aim : Klebsiella pneumoniae is a clinically important pathogen and is isolated from various infections such as respiratory, urinary tract and wound infections. K. pneumoniae has several virulence agents and also due to the emergence of widespread antibiotic resistance, treatment with antibiotics has been challenged. Bacteriophages are viruses that lyse and destroy the host bacterial cell. After attachment to the host cell, they can undergo either lytic or lysogenic cycle. During the lytic cycle, the cell wall of host is lysed and replicated phage is released to invade other bacteria. Phage therapy is an old method and was hindered by the discovery of penicillin. In recent years, by emerging of antibiotic-resistant bacteria, phage therapy has revived. Therefore, present research aimed to isolate a novel bacteriophage against K. pneumoniae and suggest a safe method in the treatment of infections with highly resistant K. pneumoniae. Methods : This study was done during ۱۵ months from March ۲۰۲۰ to June ۲۰۲۱. A Multi-Drug Resistant (MDR) and strong biofilm producer K. pneumoniae was selected as host bacterial cell for isolating bacteriophages. Sewage samples, as sources of bacteriophages, were collected from several hospitals. Then, these samples were filtered and bacterial suspension was added to this sample and then incubated overnight. After incubation, bacteriophages were purified using double-layered agar method. After plating of the phage and performing a spot test, the phage was purified by picking single plaques. A high titer lysate of phage was prepared for further analysis. To determine the host range of the phage, for each strain of K. pneumoniae, double-layered agar and spot test methods were performed. The characterization and morphology of phage was revealed by Transmission Electron Micrograph (TEM). Results : The lytic activity of isolated phage was tested based on clear plaque formation. Our phage had a large clear centered plaque. In vitro bactericidal activity of phage showed that ۴۵.۳% of K. pneumoniae isolates were sensitive to phage. Based on the results of electron microscopy, the isolated phage belonged to the siphoviridae family. Conclusion : Bacteriophages have many advantages such as their specificity to host bacteria, single dose applications and low costs. Therefore, more studies are needed on these agents so that in the future they can be widely used as an alternative in the treatment of antibiotic-resistant bacteria.

bacteriophage, Klebsiella pneumoniae, MDR, antibiotic-resistant