Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 18 3 2026 06 07 338 344 Muhammad Wasam Institute of Microbiology, Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore, Pakistan Ali Sheikh Institute of Microbiology, Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore, Pakistan Aftab Anjum Institute of Microbiology, Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore, Pakistan Muhammad Beig Institute of Microbiology, Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore, Pakistan Sehrish Firyal Institute of Biochemistry and Biotechnology, Faculty of Biosciences, University of Veterinary and Animal Sciences, Lahore, Pakistan Aleena Kokab Institute of Microbiology, Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore, Pakistan Syed Tahir Institute of Microbiology, Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore, Pakistan Tauqeer Mahmood Poultry Research Institute, Rawalpindi, Pakistan Muhammad Shahzad Veterinary Research Institute, Lahore, Pakistan 2025 06 30 2025 12 18 Background and Objectives: 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. 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. https://ijm.tums.ac.ir/index.php/ijm/article/view/5594 https://ijm.tums.ac.ir/index.php/ijm/article/download/5594/1893