COMPARISON OF SELECTIVE AND NONSELECTIVE ENRICHMENT MEDIA FOR THE ISOLATION OF LISTERIA SPECIES FROM RETAIL FOODS

Enrichment in a nonselective medium, Buffered Peptone Water (BPW) was compared with selective enrichment in University of Vermont Medium (UV MI and UVMII) for the isolation of Listeria spp. from foods. The selec tivity of the 2 types of media for the pathogenic strain, Listeria mon ocytogenes, was also compared. In total, 221 food samples including be efburgers, ham, turkey, lettuce broccoli, carrots, coleslaw: salads, f ish and ice cream, were purchased from local retail outlets and examin ed for the presence of Listeria species and L, monocytogenes using bot h enrichment media. Listeria species were detected in 57 (25.8%) sampl es using UVM, and 56 (25.3%) using BPW. L. monocytogenes was present i n 33(14.9%) samples enriched in UVM and in 29(13.1%) samples enriched in BPW. The advantages and disadvantages of selective and nonselective enrichment for detection of listeria species from a range of foods ar e discussed.