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Master's Dissertation
DOI
10.11606/D.9.2006.tde-07122006-151636
Document
Author
Full name
Marco Aurélio Vianello
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2006
Supervisor
Committee
Mamizuka, Elsa Masae (President)
Barone, Antônio Alci
Martinez, Marina Baquerizo
Title in Portuguese
Caracterização genotípica dos fatores de virulência e seu regulador "agr" em cepas de "Staphylococcus aureus" sensíveis à oxacilina
Keywords in Portuguese
Fatores de virulência
Sensibilidade oxacilina
Staphylococcus aureus
Abstract in Portuguese
A capacidade do Staphylococcus aureus escapar do sistema imune do hospedeiro é atribuída à existência de algumas exotoxinas, as quais são codificadas por genes acessórios. A expressão de genes codificadores de exotoxinas é controlada por reguladores, tais como o agr (acessory gene regulator), sendo identificados 4 tipos polimórficos deste regulador. Neste estudo, foram utilizadas 37 isolados de Staphylococcus aureus, sensíveis à oxacilina, originados de laboratórios e hospitais públicos e privados brasileiros. Utilizou-se a técnica de PCR para a amplificação dos genes codificadores dos fatores de virulência estudados e do tipo de agr presente em cada cepa. A técnica da eletroforese em campo pulsado (PFGE) foi utilizada para se verificar a existência clonal entre os isolados. Observou-se que o gene codificador de enterotoxina mais freqüentemente isolado foi o gene sea, todos relacionados com o tipo III de agr. Observou-se, também, alguns pontos divergentes com publicações anteriores como a presença dos genes seb e tst na mesma cepa (33%), cuja relação julgava-se não ser muito freqüente, o mesmo acontecendo com os genes tst e lukElukD. Não se encontrou isolado portador dos genes codificadores das toxinas esfoliatinas. Segundo a técnica de PFGE, não houve relação clonal entre os isolados. Conclui-se, portanto, que as bases moleculares da patogenicidade do S. aureus são multi-fatoriais, dependendo não somente da presença como também da expressão de alguns genes acessórios como também do tipo de agr presente.
Title in English
Genotipic characterization of virulence factors and agr of Staphylococcus aureus oxacillin sensitive
Keywords in English
Oxacillin sensitive
Staphylococcus aureus
Virulence factors
Abstract in English
The capacity of the Staphylococcus aureus to escape from the immune system of the host is conferred to the existence of some exotoxins, which are codified by accessory genes. The expression of the genes of exotoxins is controlled by regulators, such as agr (acessory gene regulator), being identified four different types of this regulator. In this study, it had been used 37 strains of Staphylococcus aureus, sensible to the oxacillin, proceeding from public and private Brazilians laboratories. It had been used the PCR technique for detention of the genes of the virulence factors and the agr type present in each strain. The PFGE had been used for detectation of clonal relationship between the strains. Thus, it was observed that the most frequently determined gene coder of enterotoxin was sea (100% were related as type of agr III). it was observed divergent points to the studies carried through in other countries, like strains with coders genes of seb and tst (33%).This correlation, the literature judged not to be frequent, the same happening for the simultaneous presence of tst and lukE-lukD. It was not found in this study strains carrying of exfoliatin toxins. According to PFGE, there wasn' t evidence of clonal relationship between the strains. It is concluded, therefore, that the molecular bases of the pathogenicity of the S. aureus are multifactorial, depending not only on the presence, as also of the expression of some accessory genes and the agr type present.
 
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MarcoAurelioVianello.pdf (814.20 Kbytes)
Publishing Date
2007-02-15
 
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