Importance of intestinal microbiota in foodborne diseases

Foodborne diseases are an important health problem that affect millions of people every year and especially lead to children mortality. Malpractices did during the production, preparation, cooking, and consumption of foods and the occurrence of pathogen contamination lead to diseases caused foodborne disease. There are many foodborne pathogens, but most of these diseases occur from bacterial sources. Although the microbiota of the human gastrointestinal system is colonized by trillions of bacteria, these bacteria are in a symbiotic relationship with the host. The intestinal microbiota with enough function to be considered as an additional organ in the body contributes to host defense with the mechanisms of colonization resistance, to prevent the colonization of pathogenic bacteria enter to the gastrointestinal system and prevent to develop infection by pathogenic bacteria. The healthy intestinal microbiota fights directly against pathogen bacteria by producing antibacterial compounds and inhibitory metabolites and by contact-dependent killing; by interfering with pathogen virulence; entering the race for the physical area, food sources and metabolites such as trace elements, vitamins, carbon sources. In addition, regulation of the intestinal epithelial cell function by preserving both intestinal epithelial barrier and related immune tissue functions, stimulation of innate immunity and by modulating adaptive immune responses, B cells, T cells, and direct antigen presentation; thus, it prevents binding of pathogens bacteria to the intestinal surfaces and developing an infection by colonization. The intestinal microbiota is influenced by many factors, especially dietary and antibiotic use. Unhealthy intestinal microbiota causes a decrease in the resistance to colonization and therefore an increase in susceptibility to pathogens. Therefore, the intestinal microbiota is very important in foodborne diseases. In this review, antimicrobial mechanisms of intestinal microbiota against foodborne bacterial pathogens have been discussed.