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

Salmonella Enteritidis is widespread in the world and is known to be among the most common 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.

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.

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.

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