Isolation and Characterization of Bacteriophages against Escherichia coli Isolates from Chicken Farms

The present study was conducted aiming to isolate and characterize bacteriophages with lytic activity against Escherichia coli infected poultry. A total of 72 samples of soil from 18 chicken farms were collected in six provinces in the Mekong Delta, Vietnam. Samples were primarily subjected to rapid detection methods, and then isolation of phage was done by a double agar layer method using E. coli as the host system. Phages were characterized on the basis of plaque morphology, pH susceptibility and host range. Results showed that the recovery of phages in soil was at a high proportion (73.6%), in which the percentage of phage isolates was higher from Noi chicken farms (66.6%) as compared to broiler chicken farms (58.3%). Four different phage morphotypes were observed against E. coli. There was a high rate of phages which existed at pH 2.0 at 26.4%. The percentage of phages that could survive from pH 5.0 to pH 3.0 significantly decreased from 84.9% to 39.6%. TEM analysis performed for MHH6 and PR2 which had widest host range, revealed that both phages belong to the Myoviridae family. It could be concluded that the MHH6 and PR2 phages have a wide host range and thus exhibit the potential to be used as a drug substitute tool against E. coli infection in chickens