EHEC and Salmonella in red meat production and processing

Summary

​The E. coli and Salmonella Monitoring - ESAM - method of sampling was found to be superior to sampling larger areas of carcases for determining numbers of E. coli and Salmonella on cattle and sheep.
Too few carcases were found to be contaminated with E. coli O157 so no comparisons could be made between the methods for detection and isolation of this organism.
The ESAM method therefore remains an adequate tool for monitoring process hygiene. Sampling larger areas of animal carcases resulted in an increase in the prevalence of E. coli and may be a method that could be considered for use in studies where it is more important to determine the prevalence rather than the numbers of E. coli.
An investigation into the contamination of animal environments found there were differences between groups of animals which may have been the result of differing weather conditions during the experiment.
Cattle sampled during wet weather had higher numbers and isolation rates of E. coli and E. coli O157 than animals tested under dry conditions.
Further investigation of the impact of weather conditions is necessary as this was not the purpose of the study and was only an observation.
Trucks used for transporting cattle and abattoir holding pens were contaminated with E. coli o157 and Salmonella, but at low levels.
There was a large diversity of E. coli O157 genotypes and Salmonella serotypes present in the transport and lairage environments indicating that these areas are probably contaminated from multiple sources such as different groups of animals. Although the numbers and isolation rate of pathogens from these environments was low, they may still be a source of animal contamination.
The level of contamination of sheep at slaughter appears to be animal group specific, which may relate to the source of the animals or the conditions in which they have been held prior to slaughter. The presence of pathogens on sheep carcases was low and it would seem that at least at the two abattoirs tested in this study, processing conditions are adequate for controlling carcase contamination.