We attempted to isolate
Listeria spp. from a total of 514 specimens, collected from the body surface of live swine, intestinal contents, the surface of washed carcasses and from the surface of refrigerated carcasses of slaughtered pigs.
Listeria monocytogenes was isolated from 7/124 specimens (5.6%) of the washed carcasses, 1/115 specimens (0.9%) of the refrigerated carcasses, and from 1/100 specimens (1.0%) of the body surface. L. innocua was isolated from 2/124 specimens (1.6%) of the washed carcasses, 1/100 specimens (1.0%) of rectal contents, and from 7/100 specimens (7.0%) of the body surface. The fact that the isolation of Listeria spp. was achieved even from the intestinal contents and the body surface of live swine suggested that these could be sources of swine carcass contamination.
Eight of nine isolates of
L. monocytogenes belonged to serotype 1/2c while the serotype of the remaining one was unidentifiable. In the CAMP test, all the isolates showed a positive reaction to
Staphylococcus aureus whereas they were positive for two of the three strains of
Rhodococcus equi. Pathogenicity for mice was observed in eight of the nine isolates, but not in the remaining one. Most of the isolates were resistant to various antibiotics, as was reported in other papers to date.
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