Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections
Autor(a) principal: | |
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Data de Publicação: | 2020 |
Tipo de documento: | Dissertação |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10362/113713 |
Resumo: | Diabetic Foot Ulcers (DFUs) constitute a favorable environment for colonization by opportunistic pathogens, and Staphylococcus aureus is the most frequent species isolated from DFUs. Due to the increasing dissemination of antibiotic-resistant strains, including S. aureus, antimicrobial peptides (AMPs) have been recognized as promising candidates for treating resistant bacterial infections. In this study, the AMP nisin had been combined with the natural polysaccharide guar gum to create nisin-biogel, to be evaluated as a new therapeutic approach to Diabetic Foot Infections (DFIs). In in vivo infections, bacteria may be exposed to a decreased effective concentration of antimicrobial agents, referred to as subinhibitory concentrations (sub-MICs). Sub-MICs of antimicrobial agents may lead to changes in bacteria metabolism, namely in biofilm formation ability and virulence genes expression. We analyzed nisin-biogel sub-MICs effects on six different S. aureus clinical isolates, including: (1) multiplication rate by determining optical density at 600 nm; (2) virulence gene expression, including of genes encoding for staphylococcal protein A (spA), coagulase (coa), clumping factor A (clfA), autolysin (atl), intracellular adhesin A (icaA), intracellular adhesin D (icaD) and the accessory gene regulator I (agrI), by relative quantitative RT-PCR; (3) biofilm formation by a microtiter technique; (4) Coa production using rabbit plasma; and (5) SpA release using a specific ELISA. Nisin-biogel sub-MICs contributed to a decrease in bacteria multiplication in a strain-dependent and dose-dependent manner, not influencing the typical sigmoidal pattern. A decrease on AgrI, Atl and ClfA mRNA expression, and a trend to increase SpA, Coa, IcaA and IcaD mRNA expression were observed in the presence of nisin-biogel at sub-MICs. The biofilm-forming ability of S. aureus clinical isolates exhibited a trend to increase in the presence of nisin-biogel at 1/4 and 1/8 MIC, whereas a concentration corresponding to 1/2 MIC had no effect on biofilm formation. Nisin-biogel at sub-MICs did not influence significantly coagulase production. Regarding SpA production, nisin-biogel at sub-MICs exhibited a trend to decrease the amount of SpA produced in a dose-dependent manner. These results highlight the importance of optimizing antimicrobial biogel doses before proceeding to in vivo trials, not only to obtain a maximal antibacterial effect but also to reduce the risk for upregulation of virulence factors and, consequently, undesirable effects on the treatment of DFIs. |
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Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot InfectionsDiabetic Foot InfectionsStaphylococcus aureusNisin-biogelSubinhibitory concentrationsVirulence-related factorsDomínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e TecnologiasDiabetic Foot Ulcers (DFUs) constitute a favorable environment for colonization by opportunistic pathogens, and Staphylococcus aureus is the most frequent species isolated from DFUs. Due to the increasing dissemination of antibiotic-resistant strains, including S. aureus, antimicrobial peptides (AMPs) have been recognized as promising candidates for treating resistant bacterial infections. In this study, the AMP nisin had been combined with the natural polysaccharide guar gum to create nisin-biogel, to be evaluated as a new therapeutic approach to Diabetic Foot Infections (DFIs). In in vivo infections, bacteria may be exposed to a decreased effective concentration of antimicrobial agents, referred to as subinhibitory concentrations (sub-MICs). Sub-MICs of antimicrobial agents may lead to changes in bacteria metabolism, namely in biofilm formation ability and virulence genes expression. We analyzed nisin-biogel sub-MICs effects on six different S. aureus clinical isolates, including: (1) multiplication rate by determining optical density at 600 nm; (2) virulence gene expression, including of genes encoding for staphylococcal protein A (spA), coagulase (coa), clumping factor A (clfA), autolysin (atl), intracellular adhesin A (icaA), intracellular adhesin D (icaD) and the accessory gene regulator I (agrI), by relative quantitative RT-PCR; (3) biofilm formation by a microtiter technique; (4) Coa production using rabbit plasma; and (5) SpA release using a specific ELISA. Nisin-biogel sub-MICs contributed to a decrease in bacteria multiplication in a strain-dependent and dose-dependent manner, not influencing the typical sigmoidal pattern. A decrease on AgrI, Atl and ClfA mRNA expression, and a trend to increase SpA, Coa, IcaA and IcaD mRNA expression were observed in the presence of nisin-biogel at sub-MICs. The biofilm-forming ability of S. aureus clinical isolates exhibited a trend to increase in the presence of nisin-biogel at 1/4 and 1/8 MIC, whereas a concentration corresponding to 1/2 MIC had no effect on biofilm formation. Nisin-biogel at sub-MICs did not influence significantly coagulase production. Regarding SpA production, nisin-biogel at sub-MICs exhibited a trend to decrease the amount of SpA produced in a dose-dependent manner. These results highlight the importance of optimizing antimicrobial biogel doses before proceeding to in vivo trials, not only to obtain a maximal antibacterial effect but also to reduce the risk for upregulation of virulence factors and, consequently, undesirable effects on the treatment of DFIs.Oliveira, Maria ManuelaSobral, RitaRUNJesus, Carolina de Oliveira2021-03-11T17:09:03Z2021-0120202021-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10362/113713enginfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-03-11T04:56:37Zoai:run.unl.pt:10362/113713Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T03:42:22.504924Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections |
title |
Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections |
spellingShingle |
Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections Jesus, Carolina de Oliveira Diabetic Foot Infections Staphylococcus aureus Nisin-biogel Subinhibitory concentrations Virulence-related factors Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias |
title_short |
Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections |
title_full |
Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections |
title_fullStr |
Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections |
title_full_unstemmed |
Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections |
title_sort |
Influence of a nisin-biogel on virulence factors expression by Staphylococcus aureus isolates from Diabetic Foot Infections |
author |
Jesus, Carolina de Oliveira |
author_facet |
Jesus, Carolina de Oliveira |
author_role |
author |
dc.contributor.none.fl_str_mv |
Oliveira, Maria Manuela Sobral, Rita RUN |
dc.contributor.author.fl_str_mv |
Jesus, Carolina de Oliveira |
dc.subject.por.fl_str_mv |
Diabetic Foot Infections Staphylococcus aureus Nisin-biogel Subinhibitory concentrations Virulence-related factors Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias |
topic |
Diabetic Foot Infections Staphylococcus aureus Nisin-biogel Subinhibitory concentrations Virulence-related factors Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias |
description |
Diabetic Foot Ulcers (DFUs) constitute a favorable environment for colonization by opportunistic pathogens, and Staphylococcus aureus is the most frequent species isolated from DFUs. Due to the increasing dissemination of antibiotic-resistant strains, including S. aureus, antimicrobial peptides (AMPs) have been recognized as promising candidates for treating resistant bacterial infections. In this study, the AMP nisin had been combined with the natural polysaccharide guar gum to create nisin-biogel, to be evaluated as a new therapeutic approach to Diabetic Foot Infections (DFIs). In in vivo infections, bacteria may be exposed to a decreased effective concentration of antimicrobial agents, referred to as subinhibitory concentrations (sub-MICs). Sub-MICs of antimicrobial agents may lead to changes in bacteria metabolism, namely in biofilm formation ability and virulence genes expression. We analyzed nisin-biogel sub-MICs effects on six different S. aureus clinical isolates, including: (1) multiplication rate by determining optical density at 600 nm; (2) virulence gene expression, including of genes encoding for staphylococcal protein A (spA), coagulase (coa), clumping factor A (clfA), autolysin (atl), intracellular adhesin A (icaA), intracellular adhesin D (icaD) and the accessory gene regulator I (agrI), by relative quantitative RT-PCR; (3) biofilm formation by a microtiter technique; (4) Coa production using rabbit plasma; and (5) SpA release using a specific ELISA. Nisin-biogel sub-MICs contributed to a decrease in bacteria multiplication in a strain-dependent and dose-dependent manner, not influencing the typical sigmoidal pattern. A decrease on AgrI, Atl and ClfA mRNA expression, and a trend to increase SpA, Coa, IcaA and IcaD mRNA expression were observed in the presence of nisin-biogel at sub-MICs. The biofilm-forming ability of S. aureus clinical isolates exhibited a trend to increase in the presence of nisin-biogel at 1/4 and 1/8 MIC, whereas a concentration corresponding to 1/2 MIC had no effect on biofilm formation. Nisin-biogel at sub-MICs did not influence significantly coagulase production. Regarding SpA production, nisin-biogel at sub-MICs exhibited a trend to decrease the amount of SpA produced in a dose-dependent manner. These results highlight the importance of optimizing antimicrobial biogel doses before proceeding to in vivo trials, not only to obtain a maximal antibacterial effect but also to reduce the risk for upregulation of virulence factors and, consequently, undesirable effects on the treatment of DFIs. |
publishDate |
2020 |
dc.date.none.fl_str_mv |
2020 2021-03-11T17:09:03Z 2021-01 2021-01-01T00:00:00Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10362/113713 |
url |
http://hdl.handle.net/10362/113713 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
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openAccess |
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application/pdf |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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