Genotypic and phenotypic study of staphylococci cogulase positive potencially enterotoxigenic isolated from Minas Frescal cheese manufacturers in São Paulo state.

• Grant number: 11/14319-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2012
• End date: January 31, 2014
• Field of knowledge: Agronomical Sciences - Food Science and Technology - Food Science
• Principal Investigator: Ernani Porto
• Grantee: Gabriela Oliveira e Silva
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Considering that the conditions of production of fresh cheeses are particularly favorable to the occurrence and production of enterotoxins produced by staphylococci and that these are the main microorganisms related to cases of food poisoning caused by consumption of Minas Frescal cheese, studies are necessary to trace the sources of contamination during manufacture process, as well as the genotypic identification of strains and the ability to effectively produce enterotoxins. This project aims to isolate and identify different species of staphylococci positive for coagulase test, potentially producers of enterotoxins in dairy industries of the state of São Paulo, since the quality of milk received until the final product. In three dairy plants that produce Minas Frescal cheese, samples will be collected during 12 months in different places of the production line. Strains isolated will be tested for coagulase test and will be identified genotypically in relation to species (S. aureus, S. hyicus and S. intermedius) and for the presence of genes (sea, seb, sec, sed, see, seg , seh, sei, sej) related to the production of staphylococcal enterotoxins A, B, C, D, E, G, H, I and J through analysis of polymerase chain reaction (PCR). The typing of strains will be performed by Enterobacteria bands Repetitive Intergenic Consensus (ERIC-PCR). Samples of raw and pasteurized milk and cheeses produced in dairy plants and the isolates of coagulase positive Staphylococcus spp. that show at least one of the genes related to classical toxin (A, B, C, D and E) production will also be tested for the phenotypic detection of enterotoxins using VIDAS ® Staph Enterotoxin (SET2). The data obtained in the molecular identification of strains, the incidence of strains carrying the genes related to the enterotoxins production and that effectively shows the phenotypic expression of enterotoxin production will be submitted to the chi-square test. The diversity of banding patterns found in the typing profiles of Staphylococcus spp. strains will be graphically demonstrated by a dendrogram.

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

SILVA, Gabriela Oliveira e. Genotypic and phenotypic study of potentially enterotoxigenic coagulase-positive staphylococci isolated from production lines of Minas fresh cheese in São Paulo. 2014. Master's Dissertation - Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) Piracicaba.