Occurrence of Listeria spp. and Listeria monocytogenes in half-carcasses, meat cuts, equipment, and the environment of bovine slaughterhouses in Brazil

Human listeriosis is a severe food-borne illness, with fatality rates ranging from 20 to 30 %. In Brazil, despite being an underdiagnosed and underreported disease, the presence of the microorganism in food has been the subject of important studies. However, its occurrence in slaughterhouse environments has received little attention in recent years. Therefore, the aim of this study was to determine the occurrence of Listeria spp. and L. monocytogenes in samples of environments (boning rooms, cold rooms, and slaughter rooms), equipment, half-carcasses, and retail cuts. Samples were collected from 25 slaughterhouse units belonging to five industries under the Federal Inspection Service (SIF) licensed for international trade and located in Brazilian states (São Paulo, Mato Grosso do Sul, Goiás, Mato Grosso, Bahia, Pará, and Minas Gerais), using Polymerase Chain Reaction (PCR). Primers pairs U1/LI1 for Listeria spp., and LM1/LM2 and LL5/LL6 (Invitrogen©) for L. monocytogenes were used for amplification. Listeria spp. was detected in 19.7 % (71/360) of the total samples analyzed, with detection rates of 23 % in deboning rooms, cold rooms, and half-carcasses, 15 % in meat cuts, and 10 % in slaughter rooms. In the total analyzed, L. monocytogenes was detected in 14.7 % (53/360) of the samples, with rates of 20 % in cold rooms, 15.8 % in boning rooms, 13.3 % in half-carcasses and meat cuts, and 10 % in slaughter rooms. The LM1/LM2 primer pair proved more efficient than LL5/LL6. The results of this study highlight the need for urgent measures to control the pathogen in cattle slaughterhouses in Brazil.