Investigating the Effect of Lytic Bacteriophages on Pseudomonas Aeruginosa Isolates with Multidrug Resistance (MDR) in Tehran in 2021

Introduction: Pseudomonas aeruginosa bacterium has a high resistance to most anti-Pseudomonas drugs, which has caused concern all over the world. Therefore, the effect of lytic bacteriophages on Pseudomonas aeruginosa isolates with multi-drug resistance is investigated in this research. Methods and Materials: Different strains of Pseudomonas aeruginosa bacterium were identified and isolated from different clinical samples during 5 months (May 2021 to October 2021) from hospitals and laboratories in different parts of Tehran. Moreover, antibiotic resistance was determined by disk diffusion method. Isolates with resistance to all drugs were selected and analyzed by molecular method. Then, the isolation of bacteriophages from hospital and city wastewater was performed and the presence of bacteriophages was investigated by plaque formation. After enriching and concentrating the isolated bacteriophages and staining the samples, transmission electron microscope (TEM) was used to examine the morphology of the bacteriophages. Result: Among 70 strains of Pseudomonas aeruginosa, 24 (34%) strains of bacteria had multidrug resistance to all tested antibiotics and bacteriophage plaques were seen against 22 (91%) of them. In the pictures taken by Transmission Electron Microscopy (TEM), the main bacteriophage was identified in all plaques, which were similar to Podoviridae and Plasmoviridae families. Discussion and Conclusion: The bacteriophages that were isolated have a very good bactericidal effect on isolates with multi-drug resistance of Pseudomonas aeruginosa bacterium and they can be suitable candidates for using in phage therapy against these infections.