Bacteriophage use in laying hens infected with Salmonella enterica serovar Enteritidis: prevention of intestinal and reproductive colonization

Abstract

Salmonella enterica serovar Enteritidis (SE) remains an important enteropathogen in the poultry industry and public health. Due to the limited effectiveness of control measures, lytic bacteriophages have shown a potential use as biocontrollers of SE in birds. The aim of this study was to determine the effectiveness of prophylactic therapy with phages to control intestinal and reproductive tract colonization of SE in laying hens. 22-week old Hy-Line Brown hens free of Salmonella, were treated with a mixture of three bacteriophages (10¹¹ PFU/dose/phage) and challenged with 2.4 x 10⁸ CFU of SE, 24 hours post phage treatment. On day 10 post challenge, hens were euthanatized, and individual samples of cecum, ovary and oviduct, were analyzed using qualitative and quantitative bacteriology. Eggs laid during the experience were collected and processed to detect SE. The incidence of Salmonella in ceca was similar between positive control and treated groups (96.67%) and cecal bacterial counts did not present significant differences between them (P > 0.05). In reproductive tissues, phagetherapy was able to slightly reduce the SE count in the ovary (P < 0.05), but not in oviducts (P > 0.05). This lytic activity of phages observed in ovaric tissue, encourages further efforts to elucidate the real contribution of bacteriophages as SE biocontrollers in laying hens.