To evaluate the methods of Enrichment, Direct Plating and Most Probable Number (MPN) - the latter according to Fung-Yu and conventional technique - for the detection of Listeria monocytogenes, 103 samples of different types of cheese ("minas frescal", ricotta, gorgonzola, roquefort, brie, camembert and cheddar) manufactured and marketed in the city of Rio de Janeiro - Brazil were analyzed. The enrichment method was more efficient than direct plating method, as well as than Most Probable Number method. The efficiency of the media tested have varied according to the degree of cheese contamination, the Mox agar being more effective than Palcam agar for samples with a high contamination level, like homemade" minas frescal", while for ripened cheeses (gorgonzola and roquefort) they were similar. Species other than L. monocytogenes were also observed in the cheeses samples examined, such as L. innocua (12.7%), L. grayi (5.8%) and L. welshimeri (0.97%), being L. monocytogenes found in gorgonzola, roquefort and" minas frescal" cheese samples.
Listeria spp; cheese; methods
