Listeria monocytogenes in products of animal origin in turkey

A study was carried out on 430 samples of different foodstuffs (soft cheese, raw chicken, minced beef, sausage, fish) and 400 carcase samples (sheep, young and adult cattle) for screening of Listeria monocytogenes. It was found that only one of the samples contained L. monocytogenes at > 10(3) cfu/ml in the initial examination, but another 42 samples contained L monocytogenes following an enrichment process. L. monocytogenes was isolated most frequently from raw chicken samples (18%), but was not isolated from sausage samples. Forty-three isolates were defined as serotypes by using Bacto-Listeria-O-antisera Type 1 (Difco 2300-50-2) and Type 4 (Difco 2301-50-1) except that Type poly was not used. For these reasons, all isolates were classified as type 1 or type 4 and the other was termed untypeable. Twenty-one samples were type 1, 17 were untypeable, and 5 were both serotype 4 and untypeable.