Lytic Activity of Isolated Phage from Milk Against Extended-Spectrum Beta-Lactamase Escherichia coli

 Background and purpose: Escherichia coli (E.coli) is the most common cause of urinary tract infection. The treatment strategy has been hampered by the emergence of broad-spectrum beta-lactamase-producing E.coli and its resistance to most antibiotics. Bacteriophages are suggested as an alternative treatment option. This study aimed at evaluating the lytic activity of isolated phage from unpasteurized milk against Extended-Spectrum Beta-Lactamase (ESBLs) E.coli. Materials and methods: In this experimental study, E. coli was isolated from nine urinary tract infection samples and was confirmed as broad-spectrum beta-lactamase-producing by the Kirby-Bauer method. Bacteriophage was isolated from unpasteurized milk samples. Lytic activity of phage was determined by the spot test. Phage titer was calculated using the DLA assay. The phage latent period was detected and phenotype of the phage was determined by electron microscopy. Results: Lytic activity of phage against E.coli was confirmed by the formation of an inhibition zone. The phage titer was 15×1010 PFU/ml. The images of electron microscopy confirmed the phage cocktail belonged to Myoviridae and Podoviridae families. The latent period of bacteriophage was 20 min. Conclusion: Isolated bacteriophage from unpasteurized milk is effective on broad-spectrum beta-lactamase E. coli.