Polyphenolic phytochemicals as natural feed additives to control bacterial pathogens in the chicken gut

Abstract

Poultry provides an important protein source consumed globally by human population, and simultaneously, acts as a substantial reservoir of antibiotic resistant bacterial species such as Escherichia coli , Salmonella , Campylobacter , Clostridium perfringens . These bacterial species can include commensal strains with beneficial roles on poultry health and productivity, and pathogenic strains not only to poultry but zoonotically to man. This review paper evaluates the role of phytochemicals as possible alternatives to antibiotics and natural anti-bacterial agents to control antibiotic resistance in poultry. The focus of this paper is on the polyphenolic phytochemicals as they constitute the major group; carvacrol oil (the active ingredient of oregano), thymol oil (the main ingredient of oregano), oregano oil, and tannins oil as feed additives and their mechanism of actions that might enhance avian gut health by controlling antibiotic-resistant bacterial strains spread in poultry.

Phytochemicals as Alternatives to Antibiotics in Animal Production

“…Campylobacter infection in human populations results from the handling or ingestion of undercooked poultry contaminated with this pathogen. In the United Kingdom, it is estimated that 80% of raw meat is contaminated with these bacteria [6,18]. Thus, C. jejuni was the cause of the majority of confirmed zoonotic cases in humans in 2010, registering a significant increase in human campylobacteriosis reported by the European Union.…”

“…Salmonella, the causative agent of the disease salmonellosis, is usually found in the intestinal tract of animals and humans, where it infects foods, such as poultry and eggs. Salmonellosis, as a disease transmitted through the food of animal origin, is known as a public health problem due to its high morbidity and mortality among humans [6]. Although in recent years, a reduction in salmonellosis cases has been observed, through good management of the control programs of this infection, salmonellosis still remains an important disease with an economic impact, by affecting the productive performance of animals and by making the human population sick due to consumption of contaminated eggs and meat [15,19].…”

“…coli (E. coli) is normally part of the natural intestinal microbiota of humans and animals, being the most dominant aerobic bacteria with 10 6 -10 9 colony forming units (UFC) per cm of the intestine of poultry (chicken and turkey). This bacterium is one of the first species to colonize the human and animal intestine [6,20]. Ingestion of animal foods containing antibiotic-resistant E. coli becomes a source of antimicrobialresistant bacteria in the human gut, and this may affect the use of medicinal antibiotics or cause opportunistic diseases in the future [21].…”

“…In 2005, at the European level, 3314 cases of E. coli VTEC illnesses were reported, mainly associated with the consumption of fresh beef [22]. Therefore, there is a need for alternative control measures, such as the use of natural phytochemicals, that do not develop resistance [6].…”

“…Due to the emergence of the phenomenon of antimicrobial resistance, the World Health Organization (WHO) established guidelines and recommendations to stop the use of antibiotics as growth promoters in 1997. One year later, in 1998, the EU banned the first phase for poultry, and the use of antibiotics as additives in their feed later in 2006, establishing a complete ban on the use of prophylactic antibiotics in the feed of all animals [4][5][6].…”