Commensalism and competition between Campylobacter jejuni strains in broiler chickens
Abstract I6
Presenter: Sophie Chagneau (Research Chair in Meat Safety, Department of Pathology and Microbiology, Université de Montréal, Québec, Canada)
Campylobacter jejuni (C. jejuni) is responsible for bacterial foodborne infections. Humans can be infected by the consumption of contaminated and undercooked chicken meat or liver. Campylobacteriosis is associated with a severe gastroenteritis but can degenerate in Guillain-Barre syndrome. A wide diversity of C. jejuni strains is observed in poultry production. However, for a broiler chicken flock, a single C. jejuni strain is often isolated from the caeca. A previous study in our laboratory showed that C. jejuni strains have different abilities to compete in the caeca after 7 days of colonization. We have speculated that gut colonization and extraintestinal spread to the liver by C. jejuni in broiler chickens are strain specific and differ when multi-strain colonization occurs. To test this hypothesis, two characterized C. jejuni strains with an opposite potential to compete for gut colonization were used: a weakly competitive strain named weak and a strongly competitive strain named strong. Chickens were infected at 14 days old with different ratios of the weak and strong strains alone or together. Chickens were euthanized at 21 (7 dpi) and at 35 days old (21 dpi). Liver, ileal and caecal contents were collected and submitted C. jejuni total counts on Butzler plates before being frozen until DNA extraction aiming at quantifying C. jejuni-specific genes by qPCR. Results showed that when the weak strain alone did not colonize infected chickens, this strain benefited from the strong strain colonization for its establishment in the gut and for its extraintestinal spread in chickens infected by both strains. However, when the innoculum allowed the colonization of the weak strain alone, a dominance of the strong strain in gut and an increase in the spread of the weak strain to the liver were observed in chickens infected by both strains. Based on these results, it seems that dynamics of C. jejuni intestinal chicken colonization and liver spread appear to be strain-dependent and, commensalism and competition mechanisms occur between C. jejuni strains. These results highlight the importance of limiting the introduction of new C. jejuni strains by implementing effective biosecurity measures to avoid the amplification of gut colonization and liver dissemination of strains already present on the farm.
About the presenter
After completing a bachelor’s degree in biochemistry, molecular, cellular biology and genetics at the University of Limoges in France, I completed a master’s degree in zoonosis and environment at the same University. Since 2019 summer, I joined the team of the Research Chair in Meat Safety at the University of Montreal to complete a PhD in veterinary sciences with a microbiology option under the supervision by Prof. Alexandre Thibodeau.
Presenting in Speaking session 1 - Host adaptation