Reduction of Campylobacter in broiler flocks: identification of risk factors, evaluation of increased biosecurity measures and the protective effect of the microbiota of Campylobacter free flocks (CAMPREVENT)

In the industrialized world, Campylobacter is the most important bacterial cause of human gastro-enteritis.  It is estimated that 50%-80% of all Campylobacter strains isolated from human cases are originating from the poultry reservoir. The overall objective of this project is to draft an (enhanced) biosecurity protocol, efficient but also easily implemented to reduce the risk that broiler flocks become colonized with Campylobacter. We  also studied the difference between the microbiota of broilers which remain Campylobacter free until slaughter and the microbiota of flocks which became or were colonized with Campylobacter.

During this study, 10 poultry farms were followed up for 3 rounds with weekly sampling of the chickens. Indicators for a range of risk factors extracted from scientific literature were studied. Using molecular typing, this led to the identification of the most important risk factors on Flemish poultry farms, including mixed farms.  Based on the results, sampling was also carried out in the slaughterhouses, especially sampling of the crates in which the chickens were transported and of the crate washing installation. Cecal droppings from Campylobacter-free flocks and flocks that became positive during rearing were analyzed to examine the bacterial composition between these two groups. Finally, a culture-independent techniques flaA-NGS was also developed and compared with the classical culture method.

At the 10 followed poultry farms, the age of 4-6 weeks was the most critical age for Campylobacter colonisation. Approximately 1/3rd of the flocks became Campylobacter positive, most of which became colonized after partial depopulation or thinning. An epidemiological link was found between contaminated material used during thinning and the remaining broilers. Efficiency of crate cleaning and disinfection proved to be a problem in most slaughterhouses, with both an inefficient C&D process and contaminated wash water being problematic. Classical cultivation still proved to be superior to culture-independent techniques such as FlaA-NGS and 16S rRNA metabarcoding, although FlaA-NGS proved to be interesting to detect multiple subtypes and 16S rRNA metabarcoding to identify potential probiotic strains. In this context, Megamonas appeared to be a potentially interesting genus to test further for its anti-Campylobacter activity. Finally, it was calculated that an increase of €0.03/kg live weight in the sales price of poultry meat should compensate for the economic loss of switching from 25% thinning to no thinning.