title: The presence of Listeria spp. in raw milk in Ontario.
abstract: Raw milk samples from bulk tanks in Ontario were analyzed for the presence of Listeria species. The overall incidence of Listeria species in raw milk was 12.4%. Listeria innocua was most frequently isolated and was found in 9.7% (43/445) of the raw milk samples, while L. monocytogenes and L. welshimeri were each found in 1.3% (6/445) of the samples. No other species of Listeria was found. Of five regions in Ontario that were examined, the eastern region had a significantly higher incidence rate of Listeria species than the western, northern, or northwestern regions. There was also a significantly lower incidence rate of Listeria species in winter than in the other three seasons. A comparison of several cold enrichment and shortened enrichment procedures demonstrated that no single procedure was totally satisfactory in isolating Listeria species.
mesh_terms: D000818:Animals; D002417:Cattle; D005260:Female; D005843:Geography; D008087:Listeria / Q000302:isolation & purification*; D008089:Listeria monocytogenes / Q000302:isolation & purification; D008892:Milk / Q000382:microbiology*; D009864:Ontario; D012621:Seasons