ANSES - Articles and news items

Occupational exposure to pesticides: Challenges for research, evaluation and prevention

Industry news  •  21 October 2014  •  European Food Safety Authority

The French food safety agency and the European Food Safety Authority are organising a joint conference on October 28 and 29 to present an overview of the latest developments in knowledge on occupational exposure to pesticides…

Persistence of listeria monocytogenes in equipment and premises

Issue 6 2011  •  4 January 2012  •  Brigitte Carpentier, Senior Scientist, ANSES and Olivier Cerf, Professor Emeritus, Alfort Veterinary School

Severe listeriosis (which can cause meningitis, septicemia, or still birth) is an infrequent foodborne illness. Yet, because of its high lethality (between 15 and 30 per cent) its causal agent, Listeria monocytogenes, is perceived as a major threat. Outbreaks of listeriosis were not overly common over the last 30 years, but they caused fear for the general population. In spite of strict regulations and the numerous precautions taken by the food business operators in Europe, and after a sharp decrease of incidence from 1987 to 2002, the number of cases per year again began to increase over the last five years. Therefore, two questions need to be asked: how can L. monocytogenes persist in food industry equipment and premises and cause the contamination of food, and what measures could be taken to combat its persistence?

L. monocytogenes is able to grow within a large temperature range (between slightly below 0°C and 45°C), over a large pH range (4.6 to 9.5) and at relatively low water activity (0.90). It can therefore grow in almost any food premises and equipment. The installation of L. monocytogenes is likely the easiest in refrigerated locations where the majority of other bacterial species cannot multiply. By using DNA fingerprinting methods, it has been extensively demonstrated that strains of L. monocytogenes may be repeatedly found for months or years in a same food processing plant. Places where L. monocytogenes are frequently found are floors, drains and more generally, locations where they find water and nutriments, even in minute amounts. What is worrying is that persistence is observed even where the cleaning and the disinfection are done right. Therefore, several researchers have hypo – thesised that persistent and sporadic strains possess different phenotypes.


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