Incidence of Listeria in Egyptian meat and dairy samples

A total of 180 food samples including meat (raw lean beef, frozen lean beef, and frozen chicken) and dairy products (raw milk, Zabady and Kareesh cheese) were analysed for Listeria. Isolates were differentiated using morphological, cultural, and biochemical tests and an API-Listeria kit. Zabady cheese was completely free of Listeria. The highest incidence rate (13.33%) was in frozen lean beef. Raw lean beef and milk products showed an incidence rate of 6.67%. The lowest incidence rate (3.33%) was in Kareesh cheese and frozen chicken meat samples. L. monocytogenes showed the lowest incidence rate (0.55%), isolated from one frozen lean beef sample. L. ivanovii and L. grayi showed the highest incidence rate (2.22%), isolated from 4 samples. L. innocua and L. seeligeri were positive in 3 samples (1.67%), and L. welshimeri in 2 samples (1.11%). L. monocytogenes and L. ivanovii were positive for virulence factors (hemolytic properties, and extracellular enzyme activities).