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Authors
Advisor(s)
Abstract(s)
A resistência antimicrobiana de patógenos humanos, como em Staphylococcus aureus resistente à meticilina (MRSA), é descrita pela Organização Mundial de Saúde (OMS) como um desafio global à saúde. A Epigalocatequina-3-galato (EGCG), o principal constituinte do chá verde, tem sido descrita como eficaz na reversão do fenótipo de resistência ao MRSA in vivo, demonstrando ter um efeito sinérgico contra diferentes antibióticos em estirpes isoladas de infeções hospitalares e de colonização da nasofaringe in vitro. Neste estudo, pretende-se avaliar divergências epigenéticas entre Staphylococcus aureus sensíveis à meticilina (MSSA) e MRSA, estirpes associadas a infeções comensais (N=9) e nosocomiais (N=10) e o potencial efeito modulador induzido pela exposição à EGCG em moduladores epigenéticos, concretamente, OrfX, uma metiltransferase ribossomal estafilocócica. Adicionalmente, foram também avaliados os efeitos induzidos em SpdC, um regulador pleiotrópico da expressão génica, e WalKR um sistema de regulação génica crucial para a virulência e adaptação ambiental de S. aureus. Em estirpes que diferem no seu perfil de resistência, origem e sinergismo da EGCG com diferentes antibióticos, foram obtidos os níveis transcricionais dos moduladores epigenéticos selecionados, através da extração de RNA bacteriano, conversão em cDNA e quantificação pela técnica de quantitative Real-time Polymerase Chain Reaction (qRT-PCR), com posterior tratamento estatístico.
Os resultados obtidos demonstram que diferentes fenótipos de resistência estão associados com expressões transcricionais divergentes dos genes moduladores epigenéticos em estudo e reversão do fenótipo de resistência pela EGCG, particularmente para o gene OrfX. Neste estudo é demonstrado o potencial da EGCG para tratamento antimicrobiano e/ou como adjuvante terapêutico contra microrganismos resistentes aos antibióticos.
ABSTRACT - The antimicrobial resistance of human pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), is described by the World Health Organization (WHO) as a global health challenge. Epigallocatechin-3-gallate (EGCG), the main constituent of green tea, has been described as effective in reversing the MRSA resistance phenotype in vivo, demonstrating to have a synergistic effect against different antibiotics in strains isolated from hospital infections and nasopharynx colonization in vitro. This study aims to evaluate epigenetic divergences between methicillin-susceptible Staphylococcus aureus (MSSA) and MRSA, strains associated with commensal (N=9), and nosocomial infections (N=10), and the potential modulatory effect induced by exposure to EGCG in epigenetic modulators, namely, OrfX, a staphylococcal ribosomal methyltransferase. In addition, the effects induced in SpdC, a pleiotropic regulator of gene expression, and WalKR, which is crucial for the virulence and environmental adaptation of S. aureus, have also been evaluated. In strains that differ in their resistance profile, source, and synergism of EGCG with different antibiotics, the transcriptional levels of the selected epigenetic modulators were obtained through the extraction of bacterial RNA, conversion into cDNA, and quantification by the qRT-PCR technique, with subsequent statistical treatment. The results obtained demonstrate that divergent resistant phenotypes correlate with divergent transcriptional expression of epigenetic modulator genes, and reversion of the resistant phenotype by EGCG, particularly OrfX. The study also showed the potential of EGCG as a therapeutic antimicrobial agent and/or therapeutic co-adjuvant, against antibiotic-resistant microorganisms.
ABSTRACT - The antimicrobial resistance of human pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), is described by the World Health Organization (WHO) as a global health challenge. Epigallocatechin-3-gallate (EGCG), the main constituent of green tea, has been described as effective in reversing the MRSA resistance phenotype in vivo, demonstrating to have a synergistic effect against different antibiotics in strains isolated from hospital infections and nasopharynx colonization in vitro. This study aims to evaluate epigenetic divergences between methicillin-susceptible Staphylococcus aureus (MSSA) and MRSA, strains associated with commensal (N=9), and nosocomial infections (N=10), and the potential modulatory effect induced by exposure to EGCG in epigenetic modulators, namely, OrfX, a staphylococcal ribosomal methyltransferase. In addition, the effects induced in SpdC, a pleiotropic regulator of gene expression, and WalKR, which is crucial for the virulence and environmental adaptation of S. aureus, have also been evaluated. In strains that differ in their resistance profile, source, and synergism of EGCG with different antibiotics, the transcriptional levels of the selected epigenetic modulators were obtained through the extraction of bacterial RNA, conversion into cDNA, and quantification by the qRT-PCR technique, with subsequent statistical treatment. The results obtained demonstrate that divergent resistant phenotypes correlate with divergent transcriptional expression of epigenetic modulator genes, and reversion of the resistant phenotype by EGCG, particularly OrfX. The study also showed the potential of EGCG as a therapeutic antimicrobial agent and/or therapeutic co-adjuvant, against antibiotic-resistant microorganisms.
Description
Mestrado em Tecnologias Clínico-Laboratoriais
Keywords
Staphyloccocus aureus Resistência antimicrobiana Epigalocatequina-3-galato Moduladores epigenéticos Antimicrobial resistance Epigallocatechin-3-gallate Epigenetic modulators
Citation
Mira AR. Epigenetic divergence of Staphylococcus aureus phenotypic resistant profiles and Epigallocatechin-3-Gallate modulator effect [dissertation]. Lisboa: Escola Superior de Tecnologia da Saúde de Lisboa/Instituto Politécnico de Lisboa; 2021.
Publisher
Instituto Politécnico de Lisboa, Escola Superior de Tecnologia da Saúde de Lisboa