Efficiency, cytotoxicity, and survivability evaluation of Salmonella phage cocktail against Salmonella derived from broiler sources.

Abstract

Background and aim: Salmonella is a leading cause of foodborne illnesses worldwide, often linked to poultry products. Antibiotic resistance among Salmonella strains has increased the need for alternative decontamination strategies, such as bacteriophage (phage) therapy. This study evaluates the lytic efficiency, cytotoxicity, and survivability of a Salmonella phage cocktail derived from wastewater sources.

Materials and methods: A total of 251 Salmonella enterica isolates from broiler production chains were tested against two selected phages (WP109 and WP128). The phages were characterized for lytic ability, cytotoxicity on Caco-2 cells, and survivability under simulated gastrointestinal and harsh environmental conditions. A cocktail of the phages was further tested for efficiency at different multiplicities of infection (MOIs) against representative Salmonella strains.

Results: Phage WP109 lysed 91.2% of Salmonella isolates, while WP128 lysed 78.2%. The phage cocktail exhibited a significant reduction of Salmonella counts at MOI 10⁴, achieving up to a 4.4 log CFU/mL reduction in vitro. The cocktail maintained 99.9% survivability in simulated gastric conditions and displayed no cytotoxic effects on Caco-2 cells. Moreover, it was resistant to various ionic sanitizers and pH levels ranging from 2 to 11.

Conclusion: The developed phage cocktail demonstrated high lytic efficacy, stability, and safety under simulated conditions, highlighting its potential as a biocontrol agent in the broiler production chain. These findings support its application in reducing Salmonella contamination while addressing the challenges posed by antibiotic resistance.