Occurrence and phenotypic and molecular characterization of Listeria monocytogenes and Salmonella spp. in slaughterhouses in southern Brazil

This study addressed the occurrence of Listeria monocytogenes and Salmonella spp. in bovine carcasses at two slaughterhouses in southern Brazil. Then, the antimicrobial susceptibility profile and the virulence potential of the isolates were evaluated. Two hundred carcasses were sampled at four steps of the slaughter process, with L. monocytogenes being isolated in 12 and Salmonella spp. in 17 carcasses. All L. monocytogenes isolates carried the hlyA, prfA, picA, plcB, actA, iap, mpl, inlA, inlB, inlC, and inlJ genes, while Salmonella spp. carried invA and hilA. Among the L. monocytogenes isolates, all of them presented virulence determinants and one showed multi-drug resistance. In relationship to Salmonella spp. isolates, many serogroups frequently related to outbreaks of foodborne diseases were identified and four isolates showed resistance to more than one antimicrobial agent. This data highlights the importance of a rigid hygienic-sanitary control during the slaughter process to reduce the risk of cross-contamination and lower the consumer exposure to L. monocytogenes and Salmonella spp. infections.