Prevalence and concentration of L. monocytogenes in RTE foods

Compliance of different RTE food subcategories with the L. monocytogenes FSC in 2008–2015 is presented in Figure 11. The figure includes monitoring data according to sampling stage, for the relevant food types at retail (also catering, hospitals and care homes) and at processing (also cutting plants). Data collected at ‘unspecified’sampling stages are included in the data reported at retail. The apparently higher proportion of non-compliance at processing is at least partly explained by the application of the different limit of FSCs for retail and processing (see footnote to Figure 11).

Considering the sampling stage of processing; apart from 2008 and 2009, ‘RTE fishery products’ was the food category with the highest level of non-compliance. It ranged from 3.5% to 9.6% of single samples. For ‘RTE products of meat origin other than fermented sausage’and ‘RTE products of meat origin, fermented sausage’ the level of non-compliance ranged between 0.9% and 6.8%, and 0% and 0.6%, respectively. In the case of cheese, ‘soft and semi-soft cheese’ (0.2–1.8%) overall showed a higher level of non-compliance than ‘hard cheese’ (0–0.3%). For ‘unspecified cheese,’ ‘milk, RTE’ and ‘other RTE dairy products’ respectively 0.4–3.4%, 0–1.7%, and 0–1% single samples were non-compliant.

(b)

RTE: ready-to-eat. This graph includes data where sampling stage at retail (also catering, hospitals and care homes) and at processing (also cutting plants) have been specified for the relevant food types. Data collected at the‘unspecified’sampling stage are included in the data reported at retail. The category ‘other RTE products’ includes RTE food other than: ‘RTE fishery products,’ ‘soft and semi-soft cheese,’ ‘hard cheese,’ ‘unspecified cheese,’ ‘other RTE dairy products,’ ‘milk,’ ‘RTE products of meat origin other than fermented sausage,’ ‘RTE products of meat origin, fermented sausage.’ For the non-compliance analysis of samples collected at the processing stage, the food safety criterion of‘absence in 25 g’was applied, except for samples of hard cheese and fermented sausage that were assumed to be unable to support the growth ofL. monocytogenesand for which the criterion of‘≤100 CFU/g’was applied. For the non-compliance analysis of samples collected at the retail level, the FSC of‘≤100 CFU/g’was applied. Only information on the main RTE food categories (RTEfishery products, RTE cheese and RTE meat products) is included in this graph. The number of samples at processing ranged from year to year from 456 to 13,578 for‘RTEfishery products’, from 1,132 to 40,853 for‘RTE products of meat origin other than fermented sausage’, from 14 to 1,283 for‘RTE products of meat origin, fermented sausage’, from 585 to 8,381 for

‘soft and semi-soft cheese’, from 220 to 5,897 for‘hard cheese’, from 1,365 to 4,264 for‘unspecified cheese’, from 111 to 1,890 for‘milk, RTE’, from 312 to 5,418 for‘other RTE dairy products’, and from 57 to 2,397 for‘other RTE products’. The number of samples at retail ranged from year to year from 1,356 to 7,174 for‘RTEfishery products’, from 3,264 to 16,653 for‘RTE products of meat origin other than fermented sausage’, from 85 to 2,772 for‘RTE products of meat origin, fermented sausage’, from 699 to 4,381 for‘soft and semi-soft cheese’, from 245 to 2,058 for‘hard cheese’, from 283 to 4,598 for‘unspecified cheese’, from 48 to 2,766 for‘milk, RTE’, from 605 to 5,110 for

‘other RTE dairy products’, and from 9,786 to 16,208 for‘other RTE products’.

Figure 11: Proportion of single samples at processing (a) and retail (b) non-compliant with EU Listeria monocytogenes food safety criteria based on the monitoring data collected by EFSA, 2008–2015

Considering the retail sampling stage, ‘RTE fishery products’ had the highest level of non-compliance in 2013 (2.3% of single samples), while for other years it was below 0.8%. For ‘RTE products of meat origin other than fermented sausage’ and ‘RTE products of meat origin, fermented sausage’ the highest levels of non-compliance were 0.7% (in 2013) and 0.6% (in 2011). In the case of

‘soft and semi-soft cheese’, the level of non-compliance was below 0.6%, except in 2008 (1.5%). For

‘hard cheese’ the level of non-compliance was below 0.3%, except in 2011 (0.9%) and 2014 (0.6%).

For ‘unspecified cheese,’ data have only been reported since 2011 with the highest level of non-compliance in 2013 (0.4%). For ‘milk, RTE’ the level of non-compliance was below 0.1% for all years.

This was also the case for ‘other RTE dairy products’, except in 2013 (0.3%). Between 0.05 and 0.3%

of single samples in the category‘other RTE products’were found to be non-compliant.

Although non-compliance at retail of less than 1% may be considered low, this may translate into many servings containing more than 100 CFU/g when total consumption is taken into account.

EU-wide prevalence ofListeria monocytogenesin RTE foods

The estimates of prevalence across the EU, as derived from the BLS conducted in 2010 and 2011, of L. monocytogenes-contaminated fish, meat and cheese samples, and of the proportion (%) of samples with L. monocytogenes counts exceeding the level of 100 CFU/g (among the sampled categories of RTE foods, as described above) can be found in Table13.

The EU prevalence estimate infish samples at the time of sampling was 10.4% and at the end of shelf life was 10.3%. The EU-level estimate of the proportion of samples with L. monocytogenes counts exceeding the level of 100 CFU/g at sampling was 1.0% while forfish samples at the end of shelf life it was 1.7%. Among meat products, the EU prevalence ofL. monocytogenes-contaminated samples at the end of shelf life was estimated at 2.07% while the EU-level proportion of samples withL. monocytogenes counts exceeding 100 CFU/g was estimated at 0.43%. The EU estimate of prevalence of L. monocytogenes-contaminated cheese samples at the end of shelf life was 0.47% while the EU-level estimate of proportion of samples withL. monocytogenescounts exceeding 100 CFU/g was 0.06%.

Table 13: Prevalence (%) ofListeria monocytogenes-contaminated fish, meat and cheese samples, and proportion (%) of samples with Listeria counts exceeding the level of 100 CFU/g at the time of sampling (for fish only) and at the end of shelf life, in the EU, 2010–2011 (from EFSA (2013))

Product and subtype

Number of samples

At sampling At end of shelf life Prevalence with Totalfish 2,994 10.4 (9.1–11.7) 1.0 (0.7–1.4) 10.3 (9.1–11.6) 1.7 (1.3–2.3) Cold-smokedfish 599 17.4 (14.2–21.1) 1.7 (0.9–3.2) 16.0 (13.2–19.3) 2.0 (1.1–3.6) Hot-smokedfish 525 6.3 (4.4–8.9) 1.3 (0.6–2.8) 6.7 (4.7–9.3) 1.7 (0.9–3.3) Unknown smoked

fish^(a)

1,625 8.8 (7.3–10.5) 0.6 (0.3–1.2) 9.1 (7.6–10.9) 1.8 (1.2–2.6) Gravadfish 245 12.2 (8.7–17.0) 0.8 (0.2–3.2) 12.2 (8.6–17.1) 0.8 (0.2–3.2) Total meat 3,470 ND ND 2.07 (1.63–2.64) 0.43 (0.25–0.74) Total cheese 3,393 ND ND 0.47 (0.29–0.77) 0.06 (0.02–0.24) CI: confidence interval; ND: not determined.

Portugal did not participate in the baseline survey and one non-Member State, Norway, participated. Norway is not included in the EU prevalence estimation analysis. Prevalence was based on combined detection and enumeration methods results. A food sample was considered positive ifL. monocytogeneswas detected by at least one of either the detection or the enumeration method, (i.e. a sample was regarded as positive when either the detection test result was positive and/or the enumeration test result was positive, i.e. having a count of at least 10 CFU/g). The survey specifications defined particular subsets of food products to be sampled, specifically (i) RTEfish which were hot-smoked or cold-smoked or gravad, were not frozen, and were vacuum or modified atmosphere packaged; (ii) RTE meat products which had been subjected to heat treatment, and were then vacuum or modified atmosphere packaged; (iii) RTE soft or semi-soft cheese, excluding fresh cheese. This category includes smear-ripened, mould-ripened, brine-matured or otherwise ripened, cheese made from raw, thermised or pasteurised milk of any animal species. The cheese could be packaged, or unpackaged at retail but packaged at the point of sale for the consumer. Only packaged and intact (sealed) packages, packaged by the manufacturer, were to be collected for sampling. However, in the case of cheese and meat products, products packaged at the retail outlet could also be collected for sampling.

(a): Fish which may have been hot- or cold-smoked.

Prevalence ofListeria monocytogenesin RTE foods from literature studies

The extensive literature search performed by Jofre et al. (2016) on the occurrence and levels of contamination of L. monocytogenes in a wide range of RTE foods covering the 1990–2015 period yielded 308 records eligible for data extraction. About 90% of the studies were surveys of naturally contaminated RTE foods with quantification of prevalence and/or levels of L. monocytogenes as (one of) the purpose/s of the study. Altogether, the category ‘dairy products’ was included in most records (N= 139), followed by ‘meat products’ (N= 110), ‘seafood’ (N= 79), ‘composite food’ (N= 62, including meals such as pasta- and rice-based salads, pre-cooked chilled foods, sandwiches, sushi, pastry and desserts), ‘produce’ (N= 58) and‘other types of products’(N= 16, including egg products and other un-specific/non-described‘RTE products’ in general). Some studies deal with more than one food category; therefore, the sum of records is higher than the 308 reviewed studies.

Prevalence data were available for 778 outcomes, i.e. individual-item survey results. The RTE food category with most prevalence data were dairy products (N = 276), followed by meat products (N= 173), seafood (N = 151), other products (e.g. composite products of raw materials from different categories; N= 104) and fresh produce (N = 74). In total, L. monocytogenes was detected in 78.1%, 70.5%, 51.8%, 36.5%, and 47.1% of the studies dealing with seafood, meat products, dairy products, produce and other products, respectively. Figure 12 shows the box-plot representation of the L. monocytogenes prevalence of each RTE food subcategory.

In all subcategories, the distribution of the prevalence values was asymmetric, with several outliers as well as extreme values. For the whole period, the median of the prevalence was below 10% for almost all subcategories, except for fermented sausage (10%), cold-smoked fish (13%), smoked fish (either cold- or hot-smoked; 12%) and cured/salted fish (12%). The above results need to be considered with caution due to the variations in the number of samples and differences in the sampling designs between studies.

Semi-quantitative data about L. monocytogenes levels (e.g. grouped in concentration ranges or above/below 100 CFU/g or ml) was provided in 244 studies. The highest number of semi-quantitative data points has been recorded for meat products (N =62). Quantitative data were obtained for only 14 RTE product types. More information can be found in Jofre et al. (2016).

RASFF data

Based on the criteria described in Section 2.1.2, the total number of RASFF notifications analysed for the concentration of the pathogen were 130 for the RASFF product category ‘fish and fish products,’ 126 for the RASFF product category ‘milk and milk products’ and 81 for the RASFF product category ‘meat and meat products other than poultry.’ In order to include notifications reporting

Median value is indicated by the line within the interquartile box. Outliers (O) and extreme (⋄) values correspond to values at 1.5- and 3-fold the interquartile range, respectively, from the 75th percentile.

Figure 12: Box-plot showing the Listeria monocytogenes prevalence of ready-to-eat (RTE) foods by subcategory

concentrations less than the detection limit (i.e.< 10 CFU/g) in the analysis, data were formed as CDF and the statistical analysis was performed using the Monte Carlo simulation (10,000 iterations).

Figure13 presents the CDF of the L. monocytogenes concentration for RASFF food product category ‘fish and fish products,’ ‘milk and milk products’ and ‘meat and meat products other than poultry’reported in all RASFF notifications during the years 2008–2016. For example, the concentration is over 2 log₁₀ CFU/g in approximately 80%, 65% and 65% of‘fish andfish products,’ ‘meat and meat products,’ and ‘milk and milk products,’ reported in RASFF notifications, respectively. The average concentrations were 2.61, 2.46 and 2.34 log₁₀ CFU/g for ‘milk and milk products,’ ‘fish and fish products’ and ‘meat and meat products other than poultry’, respectively. The highest maximum concentrations were 6.25, 5.32 and 4.75 log₁₀CFU/g, respectively.