[Listeria spp. in food of animal origin]

Different food samples of animal origin were analyzed for Listeria spp. Five L. innocua strains, one L. monocytogenes strain and one L. welshimeri strain were obtained from 208 samples of raw milk. The strains were typified by biochemical and serologic tests. The shortened enrichment method was chosen for isolations; Palcam and Oxford agar also permitted the growth of the seven strains. L. monocytogenes was recovered from milk of an animal with subclinical mastitis. No Listeria strains were isolated from pasteurized milk, chocolate milk or cheese samples. One L. welshimeri strain was detected in ice cream. In the case of meat food samples, the employment of two-step enrichment methods facilitated the detection of Listeria spp. A prevalence of L. ivanovii was observed in 2.5% of these samples.