IDENTIFICATION OF LISTERIA MONOCYTOGENES SEROVAR IN BEEF HOT DOGS

Recent food outbreaks of listeriosis have prompted concenrn about the presence of Listeria monocytogenes in uncooked hot dogs. Therefore 32 samples of hot dogs were collected from different eight shops at Amherst (U.S.A.) through two weeks. Total bacterial counts and Listeria monocytogenes counts were determined in these samples. Thereafter a primary identification for the 24 isolates collected was done to make sure that these isolates belonged to L.monocytogenes. This id­entificantion included serological identification for L.monocytogenes de­teced (22 strains). Analysis for the surface proteins of some of these strains (10 strains) was accomplished by SDS-PAGE. Then the virulence of L.monocytogenes strains was examined. Serological identification and the profiles of tested strains indicat­ed that all the strains belonged to virulent serovar 1/2 b. The virulence test exhibited the same result for all the strains.