Listeria monocytogenes is a potentially lethal foodborne pathogen commonly found in the environment. European Union hygiene legislation places responsibility for safety on primary production facilities, including farms, as part of a policy to introduce traceability throughout the food chain. This study aimed to determine the occurrence of L. monocytogenes in the Irish dairy farm environment and in particular the milking facility. Two hundred ninety-eight environmental samples were collected from 16 farms in the southern region of Ireland. A number of farms within the group supply raw milk to the unpasteurized milk cheese industry. The samples taken included cow feces, milk, silage, soil, water, etc. Samples were enriched in Listeria enrichment broth and incubated for 48 h, followed by plating on chromogenic agar Listeria Ottavani & Agosti and further incubation of the plates for 24 to 48 h. Presumptive L. monocytogenes isolates were purified and confirmed by PCR targeting the hly gene. Overall, 19% of the samples (57 of 298) were positive for L. monocytogenes. These were serotyped using conventional and PCR methods; serotypes 1/2a, 1/2b, and 4b made up 78% of the typeable isolates. A correlation was found between the level of hygiene standards on the farm and the occurrence of L. monocytogenes. There was little difference in the occurrence of L. monocytogenes between farms supplying milk to the unpasteurized milk cheese industry and those supplying milk for processing. This study demonstrates the prevalence of L. monocytogenes in the dairy farm environment and the need for good hygiene practices to prevent its entry into the food chain.
The design and evaluation of a remote laboratory for Programmable Logic Controller (PLC) education is presented. The primary objective of the presented remote PLC laboratory is to increase the availability of the physical laboratory. A secondary objective was to develop students' competence in designing and developing PLC programs. This specific focus on developing design skills within the PLC programming context is the originality contributed by this article. To achieve this originality, a realistic context is provided by basing the laboratory on physical PLCs and their associated industrial programming environments. This context is supported by simulated processes. These processes provide multiple examples to develop design skills and also a media-rich platform which supports problem-solving skills. The laboratory is evaluated using a pre-and post-survey based on the Computer Laboratory Environment Inventory and the results benchmarked. The pre-survey clearly identifies laboratory availability as an issue while the post-survey reveals that the remote laboratory successfully addressed this issue. The post-survey also indicates that the remote laboratory had a positive impact on the overall learning environment. In particular, students perceived that the laboratory problems were more open-ended and less influenced by the instructor.
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