Mahshid Setayesh Nia - Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
Ameneh Elikaei - Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
Ahya Abdi Ali - Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
Zeynab Rezaei - Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran

Introduction: Pseudomonas aeruginosa, a nosocomial pathogen, causes respiratory infections, particularly in individuals with cystic fibrosis (CF); it poses a significant challenge due to escalating antibiotic resistance. Phage therapy is emerging as a potential alternative approach to treating antibiotic-resistant bacteria. This study aimed to isolate and identify a highly efficacious bacteriophage targeting P. aeruginosa. Methods: Sewage samples from Mofid Children's Hospital were collected and titrated using a double-layer plaque assay. After plaque detection, the phage was isolated, and then the host range, adsorption rate, and stability were evaluated through spot tests and double-layer plaque assays. Phage morphology was determined using transmission electron microscopy (TEM). Results: Of the three sewage samples collected, one contained phage. We isolated a lytic bacteriophage that exhibited clear plaque formation and induced lysis in planktonic P. aeruginosa. TEM analysis revealed that the phage belonged to the Myoviridae family. The phage had a broad host range and demonstrated optimal stability at ۳۷ °C and pH ۷. Conclusion: The isolated phage can potentially be used for treating P. aeruginosa lung infections, offering an alternative approach to address drug-resistant isolates.

Bacteriophage, Cystic fibrosis, Myoviridae, Phage therapy, Pseudomonas aeruginosa, Antibiotic resistance