Bacteriolytic Activity of Coliphages on Diarrhea Associated E. coli

There has been an alarming increase in drug-resistant strains of diarrheagenic Escherichia coli (DEC) in developing as well as developed countries. Several cases of antimicrobial resistance in DEC have been observed in different parts of the world as a result, there has been a renewed interest in alternative antimicrobial treatments, including bacteriophages. This study was conducted to isolation and characterization of a lytic coliphage from sewage water capable to infect a variety of multidrug resistance DEC strains isolated from children suffering diarrhea, as first step to further usage a lytic coliphage in future.in this study, a coliphage was isolated using spotting method and titrated, using agar overlay technique. The host range of coliphages was assessed on a lawn of E coli bacteria. This study included determination of the latent periods and burst size of coli phage then determines the stability of coliphages to physical and chemical condition (temperature, pH and sunlight exposure).The results shown that, five phages isolate (A, B, C, D and E) were exhibiting a potent lytic activity with clear plaques (1-4mm in diameter). Fifty percent of the E coli strains were infected by phage isolates. It seems, very likely, that the coliphages belonging to 3 different groups (1, 2 and3). The phage growth cycle with a detected latent period of 20 min, a burst size of 160 plaque forming units per infected cell, it was found that the phage could survive at varied pH conditions with reduction in its numbers. A temperature of above 60°C and direct sunlight beyond 8 days was found to be deleterious for survival of the phage. Keywords: key words, coliphages, E. coli, diarrhe