Toxicological evaluation of Salmonella phage NINP13076 in BALB/c mice: Histopathological studies

Salmonella spp. represent a significant etiological agent of foodborne illnesses and constitute a notable public health challenge on a global scale. Effectively managing Salmonella contamination within the food supply chain is imperative, as it represents a significant threat to public health, potentially leading to severe illnesses with fatal consequences. A novel bio-preservative agent is required to combat Salmonella food contamination during different stages of the food supply chain. Bacteriophages are acknowledged for their safety and recognized for their efficacy in bio-food preservation. Given their consumption together alongside food, it becomes pivotal to assess their potential toxicity concerning the probiotic gut microbiota. In this research, BALB/c mice were employed to evaluate the sub-chronic oral toxicity of bacteriophages targeting Salmonella. Following 28 consecutive days of sub-chronic administration of the Salmonella phage through oral means, histopathological examinations of vital organs, including the lung, kidneys, heart, liver, and intestine, revealed normal organ structures and no significant pathological abnormalities, in both the control and experimental groups. No physical or behavioural change was noticed in the experimental mice. Furthermore, the proliferation of indicative probiotic bacteria persisted unchanged even following a 24-h incubation with the Salmonella phage. The body weight of both the control and experimental subjects, along with a comparative analysis of urine test results, exhibited no variations. Notably, the phages demonstrated no discernible impact on the probiotic microbiota, specifically the Lactobacillus and Bifidobacterium species isolated from the caecum of both mice that received treatment and those that did not. In untreated animals, the probiotic population (mean log CFU/ml) ranged from 1.9 to 2.4 log and 2.4 to 2.5 log, while in treated mice, it ranged from 2.0 to 2.3 log and 2.3 to 2.4 log for the Lactobacillus and Bifidobacterium species, respectively. The results of the investigation indicate that the oral administration of the lytic Salmonella phage showed no observable adverse effects on the animals, indicating an absence of harm.