Escherichia coli Shiga-Toxigênica (STEC) em abatedouro de bovinos no Estado de Minas Gerais

• Ano de defesa: 2008
• Autor(a) principal: Gomes, Andressa Pinheiro
• Orientador(a): Moraes, Célia Alencar de
• Banca de defesa: Vanetti, Maria Cristina Dantas , Pinto, Cláudia Lúcia de Oliveira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso embargado
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Microbiologia Agrícola
• Departamento: Associações micorrízicas; Bactérias láticas e probióticos; Biologia molecular de fungos de interesse
• País: BR
• Palavras-chave em Português: Escherichia coli; Toxinas; Bovino; Matadouros; Bactérias patogênicas; Reação em cadeia de polimerase
• Palavras-chave em Inglês: Escherichia coli; Toxins; Cattle; Slaughterhouses; Pathogenic bacteria; Polymerase chain reaction
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/5376

Shiga-toxigenic Escherichia coli, STEC, has emerged as a pathogen that can cause food-borne infections and severe and potentially fatal diseases such as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). Most HC and HUS outbreaks have been attributed to strains of entero-hemorrhagic serotype O157:H7, but there is growing interest on the risk to human health associated with the non-O157 STEC serotypes carried by beef products contaminated by ruminant feces. This study aimed to determine the occurrence of STEC in a cattle slaughterhouse located in the State of Minas Gerais. Sampling was carried out in two lots; Lot A with 75 bovines and Lot B with 51 animals in three stages of the slaughtering line: removal of skin after bleeding, carcass after sawing, and feces during evisceration. Samples were collected from ten animals of each lot. The samples were enriched in modified EC broth (mEC) and modified EC added with novobiocin (mECn) followed by isolation of typical colonies on Sorbitol MacConkey Medium. Two hundred and forty-one bacterial isolates obtained from the two lots, were identified as E. coli. Of these, 104 were derived from the skin, 93 from fecal material and 44 from carcasses. Polymerase chain reaction detected the stx gene in 18 isolates of E. coli. These isolates were obtained from six animals: four were of fecal origin and come from lot A; two were from carcasses from lot B. Enrichment in mECn resulted in isolates originated from one animal, whereas in mEC, the isolates were originated from five bovines. Isolates stx positive were analyzed for the hlyA gene encoding enterohemolysin. Four hlyA positive isolates originated from two bovines, one from lot A and another from lot B. Two displayed the entero- hemolytic phenotype and were isolated from the carcass. Ten of the 18 potentially STEC isolates showed cytotoxic effect on Vero cells. Eight isolates from three different animals had the stx PCR amplicons sequenced. The translated sequences obtained from stx of three isolates from the carcass and of one isolate from feces corresponded to Stx2, showing 98% to 99% identity, with references at the GeneBank (NCBI). The sequences inferred from four amplicons obtained from isolates of faecal origin corresponded to Stx1, with 94% to 96% identity. The presence of STEC in the feces and carcasses of cattle at a slaughterhouse in the state of Minas Gerais emphasizes the importance of establishing a HACCP system and the need for implementation, evaluation, and validation of control measures to minimize the risk of cross-contamination during and after slaughter.