Background: Escherichia coli (E. coli) is the most common cause of urinary tract infection (UTI) and typically treated with antibiotics. Unrestricted use of antibiotics may lead to the emergence of antibiotic-resistant bacteria. The present study aimed to isolate and characterize phages against E. coli from infected urine samples and to determine the lytic activity of phages against E. coli in vitro.
Methods: The present experimental study was conducted in the Laboratory of Bouali Sina Hospital (Sari, Iran) in May 2018. E. coli was identified from nine urine samples of patients with UTI using the conventional microbiological methods. Bacteriophages were isolated from the infected urine specimens and their lytic activity was determined using the spot test. The titer of the bacteriophages was measured using the double-layer agar technique. The morphology of the bacteriophages was revealed using transmission electron microscopy and the latent time period and burst size were determined. Data were analyzed using SPSS software package (version 20.0).
Results: E. coli was isolated from infected nine urine samples. The lytic activity of bacteriophages against E. coli was determined using the spot test by observing the formation of inhibition zones. Transmission electron microscopy showed E. coli phages belonging to the Myoviridae family. The latent time period was 20 minutes with a burst size of 1,200 plaque-forming unit (PFU) per infected cell. The results of the double-layer agar assay showed that the titer of bacteriophages was 20×108 PFU/ml.
Conclusion: The E. coli bacteriophage was isolated and characterized from infected urine samples and their lytic activity against E. coli was determined in vitro.