Occurrence and Distribution of Listeria monocytogenes and Other Listeria Species in Ready-to-Eat and Raw Meat Products

摘要

The present study was undertaken to estimate the occurrence and distribution of Listeria monocytogenes and other Listeria species in ready-to-eat food items (pasteurized milk, cheese, ice cream, and cakes) and raw meat products (minced beef, pork, and chicken carcasses). A total of 711 randomly selected samples were collected from supermarkets and pastry shops in Addis Ababa, Ethiopia. Listeria monocytogenes and other Listeria species were isolated and identified according to the techniques recommended by the International Organization for Standardization (ISO 11290-1). Serotyping of L. monocytogenes strains was carried out at the French Food Safety Agency (AFSSA), Ploufragan, France. Of the 711 food samples examined, 189 (26.6%) were Listeria positive of which 34 (4.8%) were L. monocytogenes. Pork was the most contaminated with Listeria species (62.5%) followed by minced beef (47.7%), ice cream (42.7%), soft cheese (16.8%), chicken carcasses (16.0%), and cakes (12.1%). All pasteurized milk and cottage cheese samples examined were Listeria negative. Listeria monocytogenes strains were isolated in ready-to-eat food items consisting of ice cream (11.7%), cakes (6.5%), and soft cheese (3.9%) and in meat products ranging from 3.7% to 5.1%. Among the34 isolates of L. monocytogenes serotyped, serotypes 4b/4e (n = 32), 4c, and 4e (n = 2) were identified. The presence of L. monocytogenes in some ready-to-eat food items could pose public health hazards to the consumer, particularly to the high-risk group of the population.