TABLE 3 |.
Ability of modified Moore swabs (mMS) compared to 0.45 um filters to recover Listeria from 29 paired 9-L and 1-L grab samples, respectively.
| Speciesa | Prevalence (No. Pos.) |
Proportion of |
P-value for McNemar’s χ2b | Kappac |
|||
|---|---|---|---|---|---|---|---|
| mMS | Filters | Pos. Agreement | Neg. Agreement | Score (95% CI) | P-value | ||
| L. seeligeri | 7% (2) | 17% (5) | 29% | 90% | 0.375 | 0.21 (−0.42, 0.84) | 0.278 |
| L. monocytogenes | 3% (1) | 24% (7) | 0% | 84% | 0.070 | −0.06 (−0.69, 0.56) | 0.581 |
| Listeria spp. excluding monocytogenes | 7% (2) | 38% (11) | 15% | 76% | 0.012 | – | – |
| Listeria spp. including monocytogenes | 10% (3) | 62% (18) | 10% | 49% | <0.001 | – | – |
Due to the small number of samples that were L. innocua, L. marthii, and L. welshimeri positive (i.e., two samples each) analyses could not be performed to compare recovery using mMS and 0.45 μm filters.
McNemar’s χ2 square tests for symmetry in a two-by-two contingency table; a P < 0.05 indicates significant disagreement in the number of mMS and the number of filters that were positive for the target organism.
Cohen’s Kappa score is a measure of the level of agreement between two tests beyond what would have been expected by random chance. A p < 0.05 indicates that the extent of agreement is greater than expected by random chance. Due to the identification of significant disagreement in Listeria spp. recovery by mMS compared to 0.45 um filter by McNemar’s χ2 test, the kappa test was not performed to determine if there was significant agreement in Listeria spp. recovery by mMS compared to 0.45 μm filter.