Table 2.
Detection of Listeria in 743 salads, sandwiches, food ingredients and environmental samples collected at the premises of Company X
| Number of samples tested (%) | ||||||
|---|---|---|---|---|---|---|
| 2016 | 2017 Jan–June | 2017 July–Dec | 2018 | 2019 | 2020 | |
| Salads (finished products, n = 13) | ||||||
| L. monocytogenes detected | 0 | 0 | 2 (15%) | 0 | 0 | 0 |
| Listeria species (not L. monocytogenes) detected | 0 | 0 | 3 (23%) | 0 | 0 | 0 |
| Listeria not detected | 0 | 0 | 8 (62%) | 0 | 0 | 0 |
| Total tested | 0 | 0 | 13 | 0 | 0 | 0 |
| Sandwiches (finished products n = 259) | ||||||
| L. monocytogenes detected | 1 (20%) | 0 | 3 (5%) | 2 (2%) | 0 | 1 (10%) |
| Listeria species (not L. monocytogenes) detected | 1 (20%) | 0 | 4 (7%) | 15 (12%) | 10 (17%)a | 0 |
| Listeria not detected | 3 (60%) | 6 (100%) | 48 (87%) | 108 (86%) | 48 (83%) | 9 (90%) |
| Total tested | 5 | 6 | 55 | 125 | 58 | 10 |
| Food ingredients (n = 163) | ||||||
| L. monocytogenes detected | 0 | 0 | 2 (8%) | 2 (6%) | 1 (1%) | 0 |
| Listeria species (not L. monocytogenes) detected | 0 | 0 | 0 | 7 (21%) | 6 (9%) | 0 |
| Listeria not detected | 0 | 0 | 23 (92%) | 24 (73%) | 63 (90%) | 35 (100%) |
| Total tested | 0 | 0 | 25 | 33 | 70 | 35 |
| Environmental samples (swabs, n = 306; and water, n = 2) | ||||||
| L. monocytogenes detected | 0 | 0 | 8 (13%) | 0 | 2 (1%) | 0 |
| Listeria species (not L. monocytogenes) detected | 0 | 0 | 0 | 5 (11%) | 18 (11%) | 0 |
| Listeria not detected | 0 | 0 | 55 (87%) | 42 (89%) | 136 (87%) | 42 (100%) |
| Total tested | 0 | 0 | 63 | 47 | 156 | 42 |
All Listeria detected at <20 cfu/g except for awhere L. seeligeri was detected at 40 cfu/g in a chicken mayonnaise sandwich.