Listeria adulteration not rife but still a concern, finds EFSA

The first part of EFSA’s analysis of an EU-wide baseline survey on Listeria monocytogenes published today (Thursday) provides insights into the presence of the bacteria in certain ready-to-eat foods, such as fish, cold meats and soft cheeses.

The report shows that Listeria monocytogenes was found in 10.3% of fish, 2.1% of meat and 0.5% of cheese samples collected from supermarkets and shops at the end of shelf life.

However, the EU food safety limit (100 bacteria per gram) was exceeded only in 1.7% of fish, 0.4% of meat and 0.06% of cheese samples, in the study carried out in 2010 and 2011.  

However, given the popularity of these foods and the severe implications that Listeria infections (listeriosis) can have on human health, overall vigilance regarding the possible presence of the bacteria in food is warranted.

In the EU about 1,470 human cases were reported in 2011, with a mortality rate of 12.7%, according to the European Union Summary Report on Trends and Sources of Zoonoses, Zoonotic Agents and Food-borne Outbreaks in 2011.

Enumeration tests​

EFSA said considering the enumeration test alone, the proportion of fish samples considered positive, defined as a L.monocytogenes count of 10 cfu/g or more, was 2.2% at the time of sampling and 3.2% at the end of shelf-life.

Of the 66 fish samples at time of sampling 29 samples contained L.monocytogenes exceeding the level of 100 cfu/g.

At the end of shelf-life of the 99 fish samples with a count of 10 cfu/g or more, 52 samples contained L.monocytogenes exceeding the level of 100 cfu/g.

The proportion of packaged heat-treated meat products samples considered negative by the enumeration test was 99.1% at the end of shelf-life whereas 0.9% had a positive enumeration result.

Meat and cheese results​

Of the 32 meat products samples at the end of shelf-life that had a count of 10 cfu/g or more, 15 samples contained L.monocytogenes exceeding the level of 100 cfu/g.

Enumeration showed that only four soft or semi-soft cheese products were positive, and in only two of these products did the L.monocytogenes count exceed 100 cfu/g at the end of shelf-life.

A total of 3,053 batches of packaged (not frozen) hot or cold smoked or gravad fish, 3,530 packaged heat-treated meat products and 3,452 soft or semi-soft cheeses were sampled from 3,632 retail outlets in 26 European Union Member States and Norway (who are not a Member State) .

In the second part of the study, expected to be finalised next year, EFSA will look at the risk factors for the presence of Listeria monocytogenes in the food categories concerned and the factors favouring its growth in fish.

FSA listeria targets​

Meanwhile, the UK Food Standards Agency’s (FSA)’s Advisory Committee on the Microbiological Safety of Food (ACMSF) is meeting today (Thursday) with one of the items on the agenda focussing on the FSA’s work on listeria.

Although the decline in the number of UK laboratory-confirmed cases of L.monocytogenes infection has continued from 176 in 2010 to 163 in 2011, the numbers remain elevated (around 41%) above those observed in 2000.

Public Health England (PHE) recently reported a rise in cases in England and Wales in 2012 (from 148 in 2011 to 165 in 2012.

FSA internal analysis of data from the PHE, the Advisory Committee on the Microbiological Safety of Food and the Office of National Statistics concluded that although pregnant women remain the most vulnerable group, the greatest increase in cases is in the older population (>60 years) who have underlying conditions and/or are taking particular medication.

The agency is mulling over proposing stricter criteria for hospitals that could be absence, or a low numerical value (i.e. lower that the 100 cfu/g in the legislation), for example <20 cfu/g or <10 cfu/g.