Mily Leblanc Maridor

This work aimed at providing new methods and knowledge to study the carriage of Campylobacter in conventional pig herds. Campylobacter specific real-time PCR assays developed in this study allow a direct and reliable quantification of Campylobacter spp, Campylobacter coli and Campylobacter jejuni in complex substrates like faeces or environmental samples due to the presence of an internal control of DNA extraction and PCR amplification. To study excretion in controlled condition, we inoculated three different Campylobacter strains to specific pathogen-free pigs. Our results confirmed an asymptomatic carriage and a high excretion There is a transmission between inoculated and «contact» pigs, which are Campylobacter-free at the beginning of the study and which live in the same experimental unit. The results suggest a specific interaction between the Campylobacter species and the host. Moreover, this experimental infection allowed to calibrate two molecular typing methods, namely RFLP-PFGE and flaA PCR-RFLP. Variability was evidenced only in pigs inoculated with C. coli of porcine origin, either alone or in the mix, or in sham inoculated pigs neighbouring the latter. A discrimination threshold was established with the two methods. Finally, to describe Campylobacter infection in commercial pig herds, faecal shedding as well as contamination of pens (either empty or with animals), feed and water were monitored from birth to finishing for pigs, and during one production cycle for sows. Our study underlines the role of the sows as a Campylobacter contamination source for their piglets and the role of the environment in the transmission of Campylobacter between animals.