Efficacy of a bacteriophage cocktail in controlling Salmonella Enteritidis infection in broiler chickens

Abstract

Background and Objectives: Salmonella Enteritidis is widespread in the world and is known to be among the most com- mon agents of zoonotic food-borne illnesses. This study evaluates the efficacy of a bacteriophage cocktail — comprising SEPL01 (Siphovirus) and SEPL13 and SEPL20 (Myoviruses) — in controlling Salmonella Enteritidis infection in poultry.

Materials and Methods: A total of 168 one-day-old desi chicks were procured and randomly divided into five different groups: negative control, positive control, prophylactic, 6 h and delayed post-challenge treatment group. Birds in the positive control and trial groups were orally infected with 10⁵ CFU/ml S. Enteritidis on the fourth day. The bacteriophage was given in 10⁷ PFU/ml through oral gavage, drinkers and aerosol spray. Bacterial enumeration was done using dilution plate counting on XLD agar and bacterial reduction was determined using log10 reduction.

Results: Among the groups, the prophylactic group showed the highest log₁₀ bacterial reduction: 1.92 (Day 3), 1.79 (Day 7), and 1.23 (Day 14). Drinking water administration resulted in a log₁₀ reduction of 1.62, 1.44, and 0.91, respectively, while aerosol spray was the least effective with a log₁₀ reduction of 1.12, 0.85, and 0.52 across the same days. The treatment group receiving therapy 6 hours post-challenge exhibited a moderate level of reduction: 1.63, 1.37, and 1.22 via oral gavage; 1.43, 1.15, and 0.94 via drinkers; and 0.46, 0.15, and 0.12 via aerosol spray. The delayed post-challenge group showed smaller reductions: 1.56, 1.24, and 0.92 by oral gavage; 1.25, 0.99, and 0.79 by water; and 0.42, 0.13, and 0.10 by aerosol spray.

Conclusion: The bacteriophage therapy is highly effective in reducing Salmonella Enteritidis, demonstrating potential as an antibiotic alternative.