A comparison of two procedures for the isolation of Listeria monocytogenes from raw chickens and soft cheese.

A cold enrichment method and a modified FDA procedure were compared for the isolation of Listeria monocytogenes from raw chickens and soft cheese. L. monocytogenes was isolated from a total of 23 of 222 cheese and 70 of 160 chicken samples by either one or both methods. Neither method alone yielded all isolates from the two food types. Only 12 cheese and 13 chicken samples were shown to be positive by both methods, although the serotypes isolated were not always identical. On some occasions one method yielded L. monocytogenes while the other produced a different Listeria sp. Reasons for differences in the performance of the two procedures and various points of technical interest are discussed.