Caracterização fenotípica, genotípica e avaliação por PCR do potencial enterotoxigênico de Staphylococcus aureus isolados de amostras de leite cru refrigerado

• Ano de defesa: 2013
• Autor(a) principal: Junia Pacheco Teixeira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Enterotoxinas estafilocócicas; Concentração inibitória mínima; FemA; Leite bovino; Mastite; mecA; MRSA; PCR multiplex; Staphylococcus aureus; Leite Análise; Enterotoxinas; Estafilococos aureos; Reação em cadeia de polimerase
• Link de acesso: http://hdl.handle.net/1843/SMOC-9QBPYC

Staphylococcus aureus has been associated with foodborne outbreaks, due to the ability to produce enterotoxin. Among the foods involved in these poisonings are milk and its derivatives, due to contamination by these pathogens that are the main cause of bovine mastitis. This work was performed to identify S. aureus and assessing their enterotoxigenic potential, from refrigerated raw milk samples of cattle, obtained from the Laboratory of Analysis of Quality of Milk Veterinary School, UFMG (LabUFMG) in the period July 2009 to March 2010. 251 samples were analyzed for bulk tank milk and these were obtained 278 strains of S. aureus (86.06%) and 45 isolates of coagulase-negative SCN (13.93%), by routine microbiological methods. These isolates were analyzed by PCR and conventional biplex for amplification of the mecA and femA genes and for investigation of multiplex PCR for genes encoding enterotoxins. The percentage of 82.06%, for the presence femA gene among isolates of S. aureus suggests the use of this tool for the identification of the bacteria from milk. 12 isolates showed 4.31% of the mecA gene, identifying the presence of methicillin-resistant Staphylococcus aureus (MRSA), in milk samples worked. Among the staphylococcal enterotoxin SEA and SEB (1.07% each) were predominat. The presence of enterotoxin genes and samples of MRSA have highlighted the potential of enterotoxigenic S. aureus isolated from milk originating from animals with mastitis, and the risks that this may present to public health. S. aureus evaluated by disk-agar diffusion were susceptible to gentamicin (94%) and resistance to penicillin (90%) and enrofloxacin (58%). The test of minimum inhibitory concentration-MIC, the isolates of S. aureus were susceptible to enrofloxacin (92.54% and MIC90 4 mg/mL) and gentamicin (80% MIC 90 and 16mg/mL) and resistance to penicillin G (18.47% and MIC90 64 mg / mL).