Evaluation of Novel Virulent Phages Infecting the Aeromonas Hydrophila and Escherichia coli Isolated from Sewage Water Samples

Abstract

Multidrug-resistant bacteria are now emerging for almost all the present-day antibiotics. Aeromonas hydrophila D2007 and Escherichia coli W102 were isolated from fresh food and drinking water samples and they were resistant to 57.14% and 85.71% of tested common antibiotics respectively. Three bacteriophages (phages) were isolated from sewage samples. Morphological examinations suggested that phage ΦAHP7, which infects A. hydrophila D2007, belongs to the Myoviridae family and other phages ΦECP8 and ΦECP9 capable of lysing E. coil W102 belongs to Siphoviridae and Podoviridae families respectively. For the three phages, the optimal multiplicity of infection (MOI) was calculated to be 0.001. Phages were characterized by determining their host range and stability in pHs, temperatures, and salinity. The latent periods of phages ΦAHP7, ΦECP8, and ΦECP9 were 10, 20 and 10 min with average burst sizes of 53.5 ±0.5, 26.5 ±0.5 and 67.5 ±0.5 phages per infected cell respectively. The three phages gradually reduced OD600 and are able to stop the growth of A. hydrophila D2007 and E. coli W102 in vitro at a low MOI of 0.001. Phages ΦAHP7, ΦECP8, and ΦECP9 treatments achieved 1.55, 1.68 and 2.28 log CFU/g (p <0.01) reduction of viable bacterial number in red cabbage and 1.48, 1.38 and 1.68 log CFU/g (p <0.01) reduction in tomato after 30 min at room temperature (28°C) respectively. Applications of lytic ΦAHP7, ΦECP8, and ΦECP9 bacteriophages lead to a rapid reduction of A. hydrophila D2007 and E. coli W102 counts in fresh food for human consumption.