The pdf available here as downloadable material contains a practical example of the application of our Listeria PreventionTM service, which has made it possible to identify, eliminate and prevent the development niches of Listeria monocytogenes.
A company responsible for the preparation of products based on fresh meat tested positive for Listeria monocytogenes with values that were nonetheless compliant, but there had never been any detection of the micro-organism on the processing surfaces and therefore there was an apparent absence of niches.
The auditing phase of the structure made it possible to identify the niches explaining why they escaped detection and why they persisted.
- The non-compliant cleaning and disinfection protocol determined the survival of Listeria monocytogenes and the formation of niches with consequent contamination of the processed products.
- The incorrect disassembly of some equipment made complete sanitation impossible, causing Listeria niches to be generated.
- The disinfectant action was not sufficiently efficient, given the presence of biofilm.
- Listeria monocytogenes was difficult to detect on surfaces due to the use of a sponge without neutralizer.
- Isolated Listeria monocytogenes formed biofilms improving their persistence and extension in the laboratory.
The subsequent sampling phase, thanks to the molecular analysis of the DNA of the Listeria monocytogenes detected, then made it possible to trace the contamination in the plant and identify the origin of the contamination. All the isolated Listerias monocytogenes, in fact, belonged to the same cluster, which corresponded to the one present in the raw materials of a single supplier
Following this analysis, we proceeded to indicate a series of corrective actions:
- Reinforced sanitization procedure of equipment tested positive for Listeria monocytogenes.
- More accurate disassembly of equipment tested positive for Listeria
- Use of cleaning tools of different colours to differentiate and define the area of use.
- Insertion of disinfectant Didecid based on quaternary ammonium salts.
- Blocking of the supplier with raw materials contaminates with the listeria cluster monocytogenes identified.
- Use of a sponge with neutralizer and Listeria spp research in PCR.
The Listeria PreventionTM consulting service is free for Klareco customers, except for the analytical part, which is the responsibility of the food company.