Intestinal microbiota of pigs and chickens: understanding the impact of pathogenic bacteria on human health | Handles

2024-10-29 11:23:00

Microorganisms colonizing the digestive system have proven effects on the health of their host. However, the factors modulating the microbiota remain unknown. ANSES participated in the project REMICA (Review Impact MICrobiome In Assesment), funded by Efsa (European Food Safety Authority). The aim of this project was to identify the parameters that could be taken into account for include the microbiota in the assessment of risks for animal and human health. Scientists from Anses’ Ploufragan-Plouzané-Niort laboratory carried out the animal health research, while the Spanish Higher Council for Scientific Research took care of the human health aspect.

Nutrients, chemicals, food additives, presence of microorganisms: scientists first explored the scientific literature to identify the factors modulating the microbiota which have already been highlighted by previous research. They then focused on certain factors that merited further investigation.

Influence of Salmonella and Campylobacter on the microbiota of chickens

« Through the literature review, we saw that the presence of certain microorganisms modulates the composition of the intestinal microbiota in chickens, reveals Marianne Chemaly, head of the Hygiene and quality of poultry and pig products unit at Anses. We therefore focused the rest of the project on the study of the impact of the presence of Campylobacter and Salmonella on the chicken microbiota. These two bacteria, which are responsible for the main food-borne illnesses in Europe, contaminate humans during handling in the kitchen or if food is insufficiently cooked. They are pathogenic for humans but not for animals.. »

After inoculating chickens with one or both bacteria at the same time, the scientists observed that the presence of Campylobacter had little influence on the composition of the microbiota. On the other hand the presence of Salmonella reduces the richness and diversity of the intestinal microbiotawithout this having an observable effect on the health of the animals.

Increased amount of bacteria in case of co-infection

When both bacteria are present simultaneously, it has little effect on the microbiota. However, co-infection with Salmonella and Campylobacter increases the quantity of these two bacteria in the intestinecompared to the situation where each of them is alone. “ As the likelihood of these bacteria contaminating meat is proportional to their quantity in the animals’ intestines, this increases the risk to human health » explains the scientist.

A mycotoxin associated with Salmonella slows the growth of pigs

According to the scientific literature, one of the factors significantly influencing the intestinal microbiota of pigs is the presence of the mycotoxin deoxynivalenol (DON). This toxin produced by a fungus can contaminate the food of these animals. Scientists from the RIMICIA project carried out research to complete the data on the effect of this mycotoxin and find out if it promotes the proliferation of salmonella. To do this, they added DON to the pigs’ feed and inoculated some of them with salmonella. If DON did not change the amount of salmonella in the pigs’ intestines at the end of the experiment, those who received both DON and salmonella had a lower weight compared to otherseven though they had consumed the same amount of food. The effect of DON on the gut microbiota differed between individuals; this variability needs to be studied in more detail to be explained.

Other research, notably on the link between animal welfare and the intestinal microbiota, was carried out during this project. The results should be published in the coming months.

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