In Vitro Evaluation of Bacteriophage Efficacy against Diarrhea-Causing Escherichia coli

Bacteriophages replicate within bacterial hosts, utilizing the host's biosynthetic machinery to release progeny phages. With the rise of antibiotic-resistant bacteria, there is renewed interest in bacteriophages as effective therapeutic agents. In this study, three bacteriophages—PA, PB, and PC—were isolated and tested against E. coli strains 7, 17, and 20. We focus on the initial characterization of the lytic phage PA against E. coli strain 7. Bacterial identification was achieved through biochemical methods, including Eosin methylene blue agar growth, microscopy, catalase, and urease tests. Phage PA demonstrated significant inhibition of bacterial growth over 16 hours compared to an unexposed control. Notably, this bacteriophage exhibited a limited host range, effectively lysing only three bacterial strains among the 15 tested. Phage PA remained stable at 37°C and pH 7, highlighting its potential utility in controlling pathogenic E. coli infections. The extracted genome analysis indicated that phage PA is DNA-based, as evidenced by the absence of bands in DNase-treated samples and the presence of clear bands in RNase-treated samples on gel electrophoresis. This investigation of phage biological properties may provide valuable insights for the development of therapeutic interventions against multidrug-resistant E. coli.