Phenotypic and molecular characterization of Listeria spp. strains isolated from meat products in Morocco

One hundred forty three Listeria strains (Listeria monocytogenes: 33, Listeria innocua: 105, Listeria ivanovii: 4, Listeria seeligeri: 1) were isolated from 229 samples of meat and meat products collected from butcher's shops and slaughterhouse. The overall incidence of L.monocytogenes in meat and meat products was 14.4%. L. monocytogenes was detected in 10 of 61 ground bovine meats, in 8 of 59 ground equine meats, in 7 of 22 raw bovine sausages, in 3 of 29 raw equine sausages, in 2 of 21 bovine lungs, in 2 of 18 bovine diaphragms and in 1 of 19 equine spleens. The characterization of the isolated Listeria spp. strains by serotyping and phage typing showed different serovars and phagovars. Two serovars of Listeria monocytogenes were recovered, 4b (22 strains, 66.66%) and 1/2b (11 strains, 33.33%). Only 3 strains of Listeria monocytogenes (9.09%) were phage-typable among the thirty-three strains tested. Strains were also studied by DNA macrorestriction patterns obtained after cleavage with Apal and Ascl, and separation by pulsed field gel electrophoresis. Seven different clones of L.monocytogenes could be identified from some strains.