TABLE 5.
Comparison of L. monocytogenes isolates found recurrently and sporadically in raw-milk and nondairy food samples from eight different processors with regard to susceptibility to monocins, plasmid carriage, and resistance to cadmium
| Source | Serogroup | Status | No. of strains | Monocin type
|
Detection and mass of plasmidsa | Cadmium resistanceb
|
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | D | E | 16 | 32 | 64 | 128 | 256 | 512 | |||||
| Raw milk | 1 | Recurrent | 9 | 9 | 5/9 (29 [1], 50 [4]) | 3 | 2 | 4 | |||||||
| 1 | Sporadic | 10 | 2 | 1 | 1 | 6 | 1/10 (50) | 2 | 5 | 2 | 1 | ||||
| 4 | Sporadic | 4 | 4 | 0 | 2 | 2 | |||||||||
| Nondairy foods | 1 | Recurrent | 7 | 7 | 7/7 (29 [4], 29 and 31 [1], 50 [2]) | 7 | |||||||||
| 1 | Sporadic | 10 | 2 | 1 | 7 | 6/10 (13 [1], 29 [2], 50 [1], 55 [2]) | 3 | 1 | 6 | ||||||
| 4 | Recurrent | 5 | 5 | 0 | 5 | ||||||||||
a
Plasmid masses (in megadaltons) are shown in parentheses after the frequency (number of plasmids/total isolates) of plasmid detection; the number of plasmids with each mass is in brackets.
b
Number of isolates for which the MIC of cadmium was as indicated above each column.