Isolation and characterization of multi-drug-resistant Salmonella phages: Genomic insights and antibacterial efficacy evaluation

Abstract

Salmonella, a significant foodborne pathogen, is widely associated with foodborne diseases and poses a substantial threat to public health. This study successfully screened and identified three highly effective bacteriophages (GP1–6, GP3–1, GP3–8) capable of lysing multi-drug-resistant Salmonella. These phages were classified as tailed, circular phages belonging to the Jerseyvirus family. Efficiency of plating (EOP) tests demonstrated significant lytic activity of these phages against a wide range of Salmonella strains. They exhibited exceptional stability across a broad range of environmental conditions, including temperature, pH, UV exposure, chloroform treatment, and metal ion concentrations. Notably, these phages possess advantages such as a short latency period and high burst size, with GP3–1 achieving 889 PFU/cell—significantly higher than that reported for other Salmonella phages. In addition to effectively inhibiting Salmonella biofilm formation, these phages were also able to disrupt existing biofilms. We also evaluated the therapeutic effects of the phages and their mixtures on chicken, goose, and tilapia. The results showed that phages significantly inhibited Salmonella growth, especially at 25 °C, where the maximum reduction was 2.28 log CFU/cm². Notably, while single phages caused a rebound in Salmonella counts after 24 h, the phage cocktail (GP1–6, GP3–1, GP3–8) did not, demonstrating stronger and more sustained inhibitory effects. This study highlights the potential of phage cocktails as an effective strategy for controlling Salmonella contamination in meat products, offering a promising alternative to traditional antimicrobial treatments and contributing to improved food safety and public health.