Y. enterocolitica (searched for in 131 refrigerators) and L. monocytogenes
were never found.
3.6. Statistical analysis
Statistical analysis of the data is shown in Tables 4 and 5.
The non-parametric analysis shows that all the bacterial counts
researched and found on the bottom are significantly higher than
those found on the wall.
Using logistic analysis, Table 5 highlights whether the respective
microbiological parameters are prevalent on the wall or on the
bottom, thereby calculating the relative risk.
The results in Table 5 show that the probability of finding the
most microorganisms (with the exception of Salmonella spp. and
CPS) is significantly greater on the bottom of the refrigerator with
respect to the wall. In particular, for the TVC the relative risk is 2.5
times greater on the bottom of the refrigerator with respect to the
wall (P value < 0.001, Wald c2 28.36). The relative risk of finding
Pseudomonas spp. and Aeromonas spp. on the bottom of the
refrigerator is 5 and 8 times higher respectively.