Role of Pre, Pro and Synbiotics in Reducing Zoonotic Pathogen Abundance, Lowering Antimicrobial Resistance and Improving Food Safety: Old Concepts with a New Perspective

Zoonotic diseases are a multifaceted beast whether bacterial, viral or fungal; they spread to people through contact with animals carrying the pathogen. An estimated 60% of human infections and at least 75% of emerging diseases are zoonotic. The World Health Organization and the World Organisation for Animal Health agree that controlling zoonoses at their animal source is the most effective and economical way of protecting public health. Since the removal of antibiotics at the sub-therapeutic level, several strategies envisaging the use of probiotics and prebiotics, or a combination of them (i.e. synbiotics), as feed additives in poultry nutrition are gaining popularity. They are found to be effective in maintaining resilient performance without medication, consequently, a key subject that led to the optimization of different types of strategies, showing increased zootechnical performance, reduced pathogen growth and maintaining animal welfare. Nevertheless, while there is emerging evidence that probiotics can help reduce foodborne pathogens, studies link this approach to antimicrobial resistance rate owing to selection pressure, gene reservoir mechanisms and horizontal gene transfer. The main genus of interest in this chapter is Campylobacter. The aim is to review the existing literature, focusing on the application of non-antibiotic nutritional strategies in poultry, including probiotics or prebiotics administered alone or in combination, cell-free supernatant, bacteriophage therapy and other non-organic molecules such as peracetic acid, to combat pathogen colonization pre-slaughter. While using established disease challenge models, the mode of action of existing probiotics can be broadly described in three ways, including, but not limited to, competitive exclusion, antagonism and stimulation of the host immune response. Although prebiotics are relatively easy to add to feeds, there are many obstacles to their utilization, mainly due to in-feed stability and viability when delivered through the gastrointestinal tract to trigger a visible response both at the microbiota and host level. European studies indicate that on-farm non-antibiotic interventions could effectively lead to a 1.0 log10 Campylobacter reduction in caeca/faecal/carcass of chickens, resulting in a 90% reduction in human infections, but the biological significance of this reduction in Campylobacter concentration and the etiopathogenesis of related zoonoses remain a question. We will provide historic perspectives and recent updates on current non-antibiotic approaches and their impact on Campylobacter presence associated with poultry, with the main interest in their impact on poultry production and human health.