Antibacterial activity of bacteriophages isolated from poultry against Shiga-toxic strains of Escherichia coli isolated from calves

摘要

The aim of the study was to evaluate the antibacterial activity of selected bacteriophages obtained from poultry against selected Shiga-positive Escherichia coli strains isolated from calves under in vitro conditions. Eight bacteriophages of the families Myoviridae and Siphoviridae, isolated from different poultry housing systems in south-eastern Poland, were used in the experiment. Bacteriophage morphology was examined with a transmission electron microscope on negative-stained slides with 2% silicotungstate. The range of lytic activity against Shiga-toxin-producing strains of E. coli was determined by a plaque assay on double-layer top agar plates. Twelve Shiga-toxin-producing E. coli strains isolated from calves were obtained from the National Veterinary Research Institute in Pulawy (Department of Hygiene of Food of Animal Origin), and nine of our own strains were collected from calves with clinical signs of diarrhoea in the Lublin region. The results obtained showed that the phages specific to E. coli isolated from poultry express strong lytic antibacterial properties against Shiga-positive E. coli isolated from calves. These phages exhibited complete lysis of E. coli strains on double-layer agar plates. This result confirms the lack of a species barrier in the antibacterial activity of bacteriophages, which suggests their usefulness in eliminating E. coli infections in cattle.