Rapid Detection of Listeria monocytogenes in Mechanically Separated Turkey Meat
The purpose of this study was to determine the level of Listeria spp., especially L. monocytogenes, in mechanically separated turkey (MST) meat samples. During four trials (n=150 samples), Listeria spp. were selected by using two enrichments (University of Vermont-modified I and II) and plating to selective Palcam agar base. A multiplex polymerase chain (PCR) reaction was used to confirm Listeria isolations. The specificity of the multiplex PCR assay was evaluated with reference strains of Listeria from the National Animal Disease Center (NADC) Culture Collection. The Listeria spp. yields a single 938-bp product, whereas L. monocytogenes yields the 938-bp product along with a 174-bp fragment. Results from trials I-IV indicated L. monocytogenes could not be detected by PCR in the UVM enrichment due perhaps to PCR inhibitors present in poultry fats and muscle myoglobin. The multiplex PCR performed from suspect colonies grown on Palcam, however, indicated 29 out of 150 (19%) of the MST meat harbored Listeria spp. Fifty-seven of 150 (38%) were confirmed positive for L. monocytogenes. Those confirmed as L. monocytogenes by PCR were serotyped and fingerprinted using enterobacterial repetitive intergeneic consensus (ERIC) motifs-PCR.