Efficacy of a Salmonella Bacteriophage Cocktail Against Multidrug-Resistant Salmonella Isolates From Clinical and...

Salmonella is a significant foodborne pathogen responsible for severe gastroenteritis and systemic infections in humans and animals. The increasing prevalence of antimicrobial-resistant Salmonella strains poses a major public health challenge. This study aimed to investigate the antimicrobial resistance patterns of Salmonella isolates obtained from various sources, including food and human clinical samples, and to study the effectiveness of bacteriophages against isolated strains.

A total of 80 S. Typhimurium isolates were obtained from two clinics between 2015 and 2022, and 16 ground meat samples were collected from agricultural markets. Standard microbiological methods were used for Salmonella isolation, including culture-based techniques and biochemical confirmation. The antimicrobial susceptibility of the isolates was determined using the disk diffusion method using 8 common antibiotics. New bacteriophages were isolated against multidrug-resistant Salmonella isolates. Electron microscopy for bacteriophage morphology investigation was employed.

Antimicrobial susceptibility testing revealed high resistance rates to tetracycline, streptomycin, ampicillin, chloramphenicol and ciprofloxacin, with multidrug resistance (MDR) observed in 16% of the isolates. The phage cocktail composed of six phages showed efficacy against 88.3% S. Typhimurium strains of different origins.

The study highlights the widespread occurrence of antimicrobial-resistant Salmonella in food and human samples. The presence of MDR strains poses a serious threat to public health, necessitating biosecurity interventions to limit the spread of resistant Salmonella strains. The bacteriophages assessed in this study demonstrated significant potential for the biocontrol of Salmonella strains. The phage cocktail may be used for both food safety and therapeutic purposes, particularly against antibiotic-resistant bacteria causing salmonellosis.