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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.