Genotypic and phenotypic study of potentially enterotoxigenic coagulase-positive staphylococci isolated from production lines of Minas fresh cheese in São Paulo

Author(s)

Gabriela Oliveira e Silva

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2014-01-23

Examining board members

Ernani Porto; Carolina Rodrigues da Fonseca; Maristela da Silva do Nascimento

• Advisor: Ernani Porto

Abstract

The production conditions of fresh cheese are favorable to the occurrence and production of enterotoxin produced by Staphylococci, which are the main microorganisms related to food poisoning cases in the world, requiring studies to trace the sources of contamination during manufacturing and genotypic identification ability of strains to produce enterotoxin. This study aimed to isolate and identify staphylococci positive for coagulase test, potentially producing enterotoxins in dairy products in the state of São Paulo, from milk receiving to final product. In three dairy producers of Minas fresh cheese, samples were collected from various points in the manufacturing process. the technique of mPCR was used to identify three coagulase-positive species (S. aureus, S. hyicus and S. intermedius) between isolates from different points of a processing dairy in the state of São Paulo. The genetic profile of the strains were evaluated by comparing the bands through the technique Enterobacteria Repetitive Intergenic Consensus (ERIC-PCR) and were graphically displayed by a dendrogram. The DNA of 102 strains isolated from samples of raw milk , pasteurized milk , curd, handler and equipment surface from dairies in São Paulo State and cheese were subjected to the polymerase chain reaction (PCR), using primers for the detection of specific fragments of the genes involved in the synthesis of toxins (SE) of type A, B , C , D, E, G , H, I and J. Of the 102 strains tested, five showed amplification of the gene fragment encoding toxin A, three for toxin C , 56 to toxin G, 59 to toxin H, 9 to toxin I, and none for toxins B D, E and J. For confirmation, each isolated strain carrying at least some of the genes related to the production of classical enterotoxinas, cheese and milk samples was subjected to detection by enterotoxigenic VIDAS® Staph Enterotoxin II (VIDAS SET2) bioMérieux. This identification reinforces the need to adopt proper hygiene practices in the dairy, avoiding thus the spread of these microorganisms and the possible production of enterotoxin . The data obtained for the molecular identification of the strains, the occurrence of strains carrying the genes related to the production of enterotoxin production and phenotypic enterotoxins were subjected to the Chi-squared test. This work confirmed that the risk of staphylococcal food poisoning is real, because enterotoxin was found in samples of pasteurized milk and cheeses. (AU)

• FAPESP's process: 11/14319-3 - Genotypic and phenotypic study of staphylococci cogulase positive potencially enterotoxigenic isolated from Minas Frescal cheese manufacturers in São Paulo state.
• Grantee: Gabriela Oliveira e Silva
• Support Opportunities: Scholarships in Brazil - Master