Bacteriophage Treatment Reduces Salmonella Colonization of Infected Chickens

Three different lytic bacteriophages ( BPs) were isolated from the sewage system of commercial chicken flocks and used to reduce Salmonella Enteritidis ( SE) colonization from experimental chickens. Ten-day-old chickens were challenged with 9.6 3 X 10(5) colony-forming units ( CFU)/ ml of a SE strain and treated by coarse spray or drinking water with a cocktail of the three phages at a multiplicity of infection ( MOI) of 10(3) plaque-forming units ( PFU) 24 hr prior to SE challenge. Chickens were euthanatized at day 20 of age for individual SE detection, quantitative bacteriology, and phage isolation from the intestine and from a pool of organs. SE detection was performed by both bacteriologic culture and genome detection by polymerase chain reaction ( PCR). Qualitative bacteriology showed that aerosol-spray delivery of BPs significantly reduced the incidence of SE infection in the chicken group ( P = 0.0084) to 72.7% as compared with the control group ( 100%). In addition, SE counts showed that phage delivery both by coarse spray and drinking water reduced the intestinal SE colonization ( P<0.01; P<0.05, respectively). BPs were isolated at 10 days postinfection from the intestine and from pools of organs from BP-treated chickens. We conclude that the phage treatment, either by aerosol spray or drinking water, may be a plausible alternative to antibiotics for the reduction of Salmonella infection in poultry.