Isolation and Characterization of a Klebsiella pneumoniae Specific Lytic Bacteriophage from a Hospital Waste-water Treatment Plant

Introduction: Phage therapy has gained interest as a potential alternative for treatment of infections caused by multidrug-resistant (MDR) pathogens. This study aimed to isolate a lytic bacteriophage with the potential to lyse clinical isolates of Klebsiella pneumoniae. Methods: Water samples were collected from a hospital waste-water treatment plant in Tehran. The samples were filtered and mixed with an overnight grown culture of K. pneumoniae. (ATCC 10031) followed by incubation at 37°C overnight. Phage titration, latent period, and burst size measurements were carried out by the double-layer agar method using the K. pneumoniae ATCC strain. The isolated phage w:as char:acterized by transmission electron microscopy (TEM), thermal, pH, and chloroform stability. Susceptibility of Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, ESBL producing K. pneumoniae and 51 MDR K. pneumoniae isolates was measured by placing 20 µl of the phage suspension (108 PFU) onto bacterial lawns followed by incubation at 37°C overnight. Formation of clear zones indicated susceptibility. Results: The isolated lytic bacteriophage formed small clear plaques with a latent period of 40 min and a burst time of 52 min, corresponding to 35-40 phage particles per infected cell. TEM results showed that the phage resembled the tailed Siphoviridae family and was designated vB_KpnS-Teh.1. The phage vB_KpnS-Teh.1 was most stable at 37°C, pH 7 and was resistant to chloroform. Conclusion: The isolated lytic phage showed specificity towards K. pneumoniae. Further research will determine its potential in the treatment of K. pneumoniae infections.