Prevalence and pathogen load of Campylobacter spp., Salmonella enterica and Escherichia coli O157/ O145 serogroup in sheep faeces collected at sale yards and in abattoir effluent in Western Australia.

Objective Develop a multiplex quantitative PCR assay to investigate the prevalence and shedding of Escherichia coli O157/ O145, Salmonella spp. and Campylobacter spp. in sheep at sale yards and abattoirs. Methods A qPCR for E. coli O157/ O145 was developed, validated and multiplexed with an existing qPCR for Campylobacter and Salmonella enterica. The absolute numbers of E. coli O157/ O145, Campylobacter and Salmonella in control samples was determined using droplet digital PCR. These were then used as the controls in the multiplex qPCR on a total of 474 sheep faecal samples collected from two saleyards over a 4-month period (April-July 2014) and 96 effluent samples from an abattoir. Results The mutiplex qPCR was specific with a sensitivity of 5 organisms/ μL faecal DNA extract for Campylobacter, S. enterica and E. coli O157/ O145. The overall prevalence of Campylobacter, S. enterica and E. coli O157/ O145 in faecal samples was 5.7%, 3.6% and 8.4% and in effluent samples was 18.8%, 6.3% and 5.2%, respectively. The pathogen loads of Campylobacter, S. enterica and E. coli O157/ O145 in faecal and effluent samples was also determined via mutiplex qPCR. Conclusions The overall prevalences of Campylobacter, S. enterica and E. coli O157/ O145 were generally low (<6%), but point prevalences ranged considerably in healthy sheep (up to 26% for E. coli O157/ O145). Further work to determine risk factors for shedding of bacterial organisms in meat sheep in the pre-slaughter period (on-farm, sale yards and lairage at abattoirs) could further reduce the risk of contamination of meat products. [ABSTRACT FROM AUTHOR]