Detection of Listeria spp. in Naturally Contaminated Seafoods Using Four Enrichment Procedures

Four enrichment procedures were evaluated for the recovery of Listeria spp. from 211 samples of raw and processed seafoods. The presence of Listeria spp. was determined in all four methods by a commercial enzyme-linked immunosorbent assay kit. The enrichments used were 1) Listeria enrichment broth (LEB); 2) buffered LEB (BLEB); 3) BLEB transferred to the same enrichment after 24 h (BLEB 24-h transfer); and 4) modified University of Vermont medium (UVM-1) transferred after 24 h to UVM-1 medium containing additional acriflavin (UVM-2). All four enrichments were incubated for a total of 48 h at 30°C. To determine the efficiency of each protocol, we compared our recovery results with those obtained by using a modified version of the Bacteriological Analytical Manual (BAM) cultural method, as described in the Federal Register of November 1, 1988. Statistical analysis showed that recovery of Listeria spp. using nonbuffered LEB for 48 h without transfer did not differ significantly from that obtained with the revised BAM method.