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E. coli O157:H7 is a foodborne pathogen mostly related to consumption of meat and vegetables. Although using antibiotics is not recommended in treatment of infections caused by this pathogen, antibiotic resistant isolates are reported. This has encouraged researchers to find alternative methods to treat and effective approaches to prevent the E. coli O157:H7 infections. Phage therapy is one of the techniques with therapeutic and biocontrol applications. The aim of this study was to find effective phages capable of lysing this pathogen. Twenty samples were searched for phages against E. coli O157:H7. The host range of the isolated phages was determined. The phages with broader host range were selected for structural study. The stability in different temperature and pH values were also performed. Phages kmuOR and kmuGH could lyse two strain of E. coli O157:H7, some clinical non-O157 E. coli strains, and a strain of Shigella flexneri, another enteric pathogen. Transmission electronic micrograph revealed that both phages belong to Myoviridae family. The two phages were resistant to pH 3 to 9.5 and temperatures 4-50°C and able to prevent the growth of E. coli O157:H7 in LB medium. Further study can prove the suitability of these phages as biocontrol or phage therapy agents. [ABSTRACT FROM AUTHOR]

Phage therapy is an old method of combating bacterial pathogens that has recently been taken into consideration due to the alarming spread of antibiotic resistance. Escherichia coli O157:H7 is a foodborne pathogen that causes hemorrhagic colitis and life-threatening Hemolytic Uremic Syndrome (HUS). There are several studies on isolation of specific phages against E . coli O157:H7 and more than 60 specific phages have been published so far. Although in vitro experiments have been successful in elimination or reduction of E . coli O157:H7numbers, in vivo experiments have not been as promising. This may be due to escape of bacteria to locations where phages have difficulties to enter or due to the adverse conditions in the gastrointestinal tract that affect phage viability and proliferation. To get around the latter obstacle, an alternative phage delivery method such as polymer microencapsulation should be tried. While the present time results are not very encouraging the work should be continued as more efficient phage treatment regimens might be found in future. [ABSTRACT FROM AUTHOR]