Iron availability modulates biofilm formation by Staphylococcus epidermidis

Iron is regarded as essential to virtually all microorganisms, although the role of this nutrient on biofilm formation by many bacterial species is unknown or poorly explored. This is the case of Staphylococcus epidermidis, a major inhabitant of the human skin, which has also become an important nosocomial pathogen. Interestingly, biofilm formation has been regarded as a pivotal feature in both commensal and clinical isolates. Recent results from our group have pointed out iron uptake as an important mechanism for S. epidermidis biofilms survival. The present work was therefore aimed at elucidating the effect of iron availability in S. epidermidis biofilm formation.To achieve that, biofilm formation of three S. epidermidis isolates was evaluated when cultured in medium presenting different iron availability levels. Interestingly, under physiological iron concentrations, biofilm formation and planktonic growth were not affected but supraphysiological concentrations displayed an inhibitory effect both on biofilm and planktonic growth. Importantly, biofilm formation and planktonic growth was also inhibited by chelation of the iron present in the culture medium, which was completely restored after iron addition in a dose-dependent manner. Our findings provide clear evidence that iron plays a pivotal role on S. epidermidis biofilm formation, and this seems to be primarily related with its effect on the bacterial growth rate. Additionally, the iron concentration range supporting bacterial growth and further biofilm development was found to be very narrow, a feature that may be explored in the future for biofilm control purposes

Host soluble factors cause changes in Staphylococcus epidermidis antibiotic susceptibility and biofilm formation ability

Staphylococcus epidermidis is a major nosocomial pathogen with a remarkable ability to adhere to the surfaces of indwelling medical devices and form biofilms. Unlike other nosocomial pathogens, the interaction of S. epidermidis with host factors has not been the focus of substantial research. This study aimed to assess the alterations in the antibiotic susceptibility and biofilm formation ability of S. epidermidis in the presence of host serum factors. S. epidermidis strain RP62A was cultured in a laboratory culture medium with or without human serum/plasma, and changes in antibiotic susceptibility, biofilm formation, and gene expression were evaluated. The data obtained revealed that exposure to host serum factors increased the susceptibility of S. epidermidis to glycopeptide antibiotics and was also detrimental to biofilm formation. Gene expression analysis revealed downregulation of both dltA and fmtC genes shortly after human serum/plasma exposure. The importance of transferrin-mediated iron sequestration as a host anti-biofilm strategy against S. epidermidis was also emphasized. We have demonstrated that serum factors play a pivotal role as part of the host’s anti-infective strategy against S. epidermidis infections, highlighting the importance of incorporating such factors during in vitro studies with this pathogen.This research was funded by the Portuguese Foundation for Science and Technology (FCT) by the strategic funding of the unit with the reference [UIDB/04469/2020].info:eu-repo/semantics/publishedVersio

Staphylococcus epidermidis biofilms are resistant to phage infection due to the protective effect of the biofilm matrix

EMBO Conference on Viruses of Microbes III: Structure and Function - from Molecules to Communities (Programme and Abstract Book)info:eu-repo/semantics/publishedVersio

Characterization of a new twortlikevirus infecting Staphylococcus epidermidis that exhibits activity against biofilm and stationary bacterial populations

Staphylococcus epidermidis is a major causative agent of nosocomial infections, mainly associated with the use of indwelling devices, on which this bacterium forms structures known as biofilms. Due to biofilms high tolerance to antibiotics, virulent bacteriophages were previously tested as novel therapeutic agents. However, several staphylococcal bacteriophages were shown to be inefficient against biofilms. Using wastewater treatment plant raw effluents, a novel phage was isolated and characterized. This virus was named phiIBB-SEP1 and TEM micrographs suggested that it belonged to the Twortlikevirus genus. Phage phiIBB-SEP1 is able to infect 41 S. epidermidis clinical isolates used in this study, and contrarily to other polyvalent viruses of the Twortlikevirus genus, phiIBB-SEP1 is highly specific for S. epidermidis strains. The genome of this phage was fully sequenced and presents the typical structure of a member of the Twortlikevirus. However, when compared to other staphylococcal members of this genus, it showed DNA sequence identities no greater than 58.2%, suggesting that phiIBB-SEP1 is a new species within this subfamily. Efficacy studies results showed that phage SEP1 is able to cause a 6 Log CFU per ml reduction of the cell titer in less than 2h for some of the clinical strains in exponential phase; and, in less than 4h for stationary phase cells (using a multiplicity of infection of 1). This phage has also the capacity of reducing, by up to 2 Log CFU per ml, 24h scraped biofilm cells. Besides CFU counting, this cell reduction was confirmed by flow cytometry counting. Additionally, live/dead flow cytometry staining allowed the observation that this phage kills biofilms bacteria in different physiological states including dormant cells. These are promising results, since the rare feature presented by this phage of infecting cells with reduced metabolic activity allied with its high broad host strain range suggest its use for therapy purposes

The protective effect of Staphylococcus epidermidis biofilm matrix against phage predation

Staphylococcus epidermidis is a major causative agent of nosocomial infections, mainly associated with the use of indwelling devices, on which this bacterium forms structures known as biofilms. Due to biofilms’ high tolerance to antibiotics, virulent bacteriophages were previously tested as novel therapeutic agents. However, several staphylococcal bacteriophages were shown to be inefficient against biofilms. In this study, the previously characterized S. epidermidis-specific Sepunavirus phiIBB-SEP1 (SEP1), which has a broad spectrum and high activity against planktonic cells, was evaluated concerning its efficacy against S. epidermidis biofilms. The in vitro biofilm killing assays demonstrated a reduced activity of the phage. To understand the underlying factors impairing SEP1 inefficacy against biofilms, this phage was tested against distinct planktonic and biofilm-derived bacterial populations. Interestingly, SEP1 was able to lyse planktonic cells in different physiological states, suggesting that the inefficacy for biofilm control resulted from the biofilm 3D structure and the protective effect of the matrix. To assess the impact of the biofilm architecture on phage predation, SEP1 was tested in disrupted biofilms resulting in a 2 orders-of-magnitude reduction in the number of viable cells after 6 h of infection. The interaction between SEP1 and the biofilm matrix was further assessed by the addition of matrix to phage particles. Results showed that the matrix did not inactivate phages nor affected phage adsorption. Moreover, confocal laser scanning microscopy data demonstrated that phage infected cells were less predominant in the biofilm regions where the matrix was more abundant. Our results provide compelling evidence indicating that the biofilm matrix can work as a barrier, allowing the bacteria to be hindered from phage infection.This study was supported by the Portuguese Foundation for Science and Technology (FCT)under the scope of the strategic funding of UIDB/04469/2020 unit, and Project PTDC/SAU-PUB/29182/2017 [POCI-01-0145-FEDER-029182]. This project received funding from the European Union’s Horizon 2020 researchand innovation programme under grant agreement No. 713640info:eu-repo/semantics/publishedVersio

Visão baseada em recursos dinâmicos: estudo das contribuições da área de Dinâmica de Sistemas (DS) para a teoria da Visão Baseada em Recursos (VBR)

This work aims to evaluate the conceptual contributions from the area of System Dynamics (SD) to the Resource Based-View (RBV) Theory, a field of study in the Strategy area. With that aim in mind, a literature review of the Strategy field in the latest years was carried out and the contributions that SD can offer in this context were analyzed. Specifically, the strategic architecture proposed by Warren (2002) is presented: it employs the two concepts to make the analysis of dependencies between resources and their dynamic impacts on organizational performance possible. As a result, it was observed that some aspects that are not addressed by the RBV theory can receive important contributions from SD, such as the opportunity to build strategic models that permit simulation, making the analysis of the interdependence between tangible and intangible resources possible, considering not only the performance of the company at a point in time, but its temporal trajectory and dynamics. This work, therefore, proposes to  extend the studies on the applications of its results in the Strategy teaching area, through the use of educational simulators which are based on those twoEl presente trabajo tiene como objetivo evaluar las contribuciones conceptuales del área de Dinámica de Sistemas (DS) para la Teoría de la Visión Basada en los Recursos (VBR), un campo de estudio del área de Estrategia. Para ello, se realizó un levantamiento bibliográfico de los últimos años en el área de Estrategia y que contribuciones el área de DS puede traer en este contexto. Específicamente, se presenta la arquitectura estratégica propuesta por Warren (2002) que utiliza los dos conceptos para posibilitar el análisis de las dependencias entre los recursos y sus impactos dinámicos en el desempeño organizacional. Como resultado, se puede percibir que algunos aspectos no abordados por la VBR pueden recibir contribuciones importantes provenientes de la DS, como la oportunidad de construir modelos estratégicos que posibiliten la simulación, permitiendo el análisis de la interdependencia entre los recursos tangibles e intangibles, considerando no apenas el desempeño de la empresa en un punto en el tiempo, sino su trayectoria temporal y dinámica. A partir de este trabajo, se pretende extender los estudios para aplicaciones de sus resultados en el área de la enseñanza de estrategia, a través de simuladores educacionales construidos con base en las dos áreas.O presente trabalho objetiva avaliar as contribuições conceituais da área de Dinâmica de Sistemas (DS) para a Teoria da Visão Baseada em Recursos (VBR), um campo de estudo da área de Estratégia. Para tanto, realizou-se um levantamento bibliográfico nos últimos anos na área de Estratégia e que contribuições a área de DS pode trazer neste contexto. Especificamente, é apresentada a arquitetura estratégica proposta por Warren (2002) que se utiliza dos dois conceitos para possibilitar análise das dependências entre os recursos e seus impactos dinâmicos no desempenho organizacional. Como resultado, pôde-se perceber que alguns aspectos não abordados pela VBR podem receber contribuições importantes provenientes da DS, como a oportunidade de construir modelos estratégicos que possibilitem a simulação, permitindo a análise da interdependência entre os recursos tangíveis e intangíveis, considerando não apenas o desempenho da empresa em um ponto no tempo, mas sua trajetória temporal e dinâmica. Pretende-se a partir deste trabalho, estender os estudos para aplicações dos seus resultados na área de ensino de estratégia, através de simuladores educacionais construídos com base nas duas áreas

VISIÓN BASADA EN LOS RECURSOS DINÁMICOS: ESTUDIO DE LAS CONTRIBUCIONES DEL ÁREA DE DINÁMICA DE SISTEMAS (DS) PARA LA TEORÍA DE LA VISIÓN BASADA EN LOS RECURSOS (VBR)

O presente trabalho objetiva avaliar as contribuições conceituais da área de Dinâmica de Sistemas (DS) para a Teoria da Visão Baseada em Recursos (VBR), um campo de estudo da área de Estratégia. Para tanto, realizou-se um levantamento bibliográfico nos últimos anos na área de Estratégia e que contribuições a área de DS pode trazer neste contexto. Especificamente, é apresentada a arquitetura estratégica proposta por Warren (2002) que se utiliza dos dois conceitos para possibilitar análise das dependências entre os recursos e seus impactos dinâmicos no desempenho organizacional. Como resultado, pôde-se perceber que alguns aspectos não abordados pela VBR podem receber contribuições importantes provenientes da DS, como a oportunidade de construir modelos estratégicos que possibilitem a simulação, permitindo a análise da interdependência entre os recursos tangíveis e intangíveis, considerando não apenas o desempenho da empresa em um ponto no tempo, mas sua trajetória temporal e dinâmica. Pretende-se a partir deste trabalho, estender os estudos para aplicações dos seus resultados na área de ensino de estratégia, através de simuladores educacionais construídos com base nas duas áreas.This work aims to evaluate the conceptual contributions from the area of System Dynamics (SD) to the Resource Based-View (RBV) Theory, a field of study in the Strategy area. With that aim in mind, a literature review of the Strategy field in the latest years was carried out and the contributions that SD can offer in this context were analyzed. Specifically, the strategic architecture proposed by Warren (2002) is presented: it employs the two concepts to make the analysis of dependencies between resources and their dynamic impacts on organizational performance possible. As a result, it was observed that some aspects that are not addressed by the RBV theory can receive important contributions from SD, such as the opportunity to build strategic models that permit simulation, making the analysis of the interdependence between tangible and intangible resources possible, considering not only the performance of the company at a point in time, but its temporal trajectory and dynamics. This work, therefore, proposes to  extend the studies on the applications of its results in the Strategy teaching area, through the use of educational simulators which are based on those twoEl presente trabajo tiene como objetivo evaluar las contribuciones conceptuales del área de Dinámica de Sistemas (DS) para la Teoría de la Visión Basada en los Recursos (VBR), un campo de estudio del área de Estrategia. Para ello, se realizó un levantamiento bibliográfico de los últimos años en el área de Estrategia y que contribuciones el área de DS puede traer en este contexto. Específicamente, se presenta la arquitectura estratégica propuesta por Warren (2002) que utiliza los dos conceptos para posibilitar el análisis de las dependencias entre los recursos y sus impactos dinámicos en el desempeño organizacional. Como resultado, se puede percibir que algunos aspectos no abordados por la VBR pueden recibir contribuciones importantes provenientes de la DS, como la oportunidad de construir modelos estratégicos que posibiliten la simulación, permitiendo el análisis de la interdependencia entre los recursos tangibles e intangibles, considerando no apenas el desempeño de la empresa en un punto en el tiempo, sino su trayectoria temporal y dinámica. A partir de este trabajo, se pretende extender los estudios para aplicaciones de sus resultados en el área de la enseñanza de estrategia, a través de simuladores educacionales construidos con base en las dos áreas

Cuidado e saúde em pacientes estomizados

Objetivo: Descrever os aspectos epidemiológicos, as complicações e as hospitalizações relacionadas à estomia. Métodos: Trata-se de um estudo transversal, descritivo e quantitativo das variáveis: sexo, idade, faixa etária, raça/cor, tempo de estomia, tipo de estomia, etiologia, complicações e internações hospitalares associadas à colostomia de 123 pacientes atendidos no ambulatório de enfermagem para pacientes estomizados de um hospital escola em Goiânia, Goiás, Brasil. Após a disposição dos dados em tabelas, utilizou-se o software Epi Info 7 para a descrição dos resultados, a análise de prevalências e a associação de variáveis. Resultados: 51,2% (n=63) dos pacientes eram do sexo masculino e houve predominância do tipo de colostomia terminal (n=68;57,6%), enquanto 24,5% (n=29) era do tipo em alça e 17% (n=20) do tipo dupla boca. Quanto à etiologia da estomia, 40,5% (n=49) ocorreu por neoplasia, 17,3% (n=21) por doença inflamatória intestinal e 9% (n=11) por trauma. O desenvolvimento de complicações esteve presente em 38 (30,89%) pacientes, sendo a dermatite periestomal a principal delas, e 9 (7%) pacientes necessitaram de internação hospitalar relacionada à estomia. Conclusão: Observa-se que os pacientes investigados apresentam predominância do sexo masculino, média de idade de 61,5 anos, raça/cor parda, de colostomia terminal e etiologia neoplásica, sendo a maioria dos pacientes portadores de colostomia há cerca de 5 anos

Secondary infections in a cohort of patients with COVID-19 admitted to an intensive care unit: impact of gram-negative bacterial resistance

Some studies have shown that secondary infections during the COVID-19 pandemic may have contributed to the high mortality. Our objective was to identify the frequency, types and etiology of bacterial infections in patients with COVID-19 admitted to an intensive care unit (ICU) and to evaluate the results of ICU stay, duration of mechanical ventilation (MV) and in-hospital mortality. It was a single-center study with a retrospective cohort of patients admitted consecutively to the ICU for more than 48 h between March and May 2020. Comparisons of groups with and without ICU- acquired infection were performed. A total of 191 patients with laboratory-confirmed COVID-19 were included and 57 patients had 97 secondary infectious events. The most frequent agents were Acinetobacter baumannii (28.9%), Pseudomonas aeruginosa (22.7%) and Klebsiella pneumoniae (14.4%); multi-drug resistance was present in 96% of A. baumannii and in 57% of K. pneumoniae. The most prevalent infection was ventilator-associated pneumonia in 57.9% of patients with bacterial infections, or 17.3% of all COVID-19 patients admitted to the ICU, followed by tracheobronchitis (26.3%). Patients with secondary infections had a longer ICU stay (40.0 vs. 17 days; p < 0.001), as well as a longer duration of MV (24.0 vs 9.0 days; p= 0.003). There were 68 (35.6%) deaths overall, of which 27 (39.7%) patients had bacterial infections. Among the 123 survivors, 30 (24.4%) had a secondary infections (OR 2.041; 95% CI 1.080 - 3.859). A high incidence of secondary infections, mainly caused by gram-negative bacteria has been observed. Secondary infections were associated with longer ICU stay, MV use and higher mortality

VISIÓN BASADA EN LOS RECURSOS DINÁMICOS: ESTUDIO DE LAS CONTRIBUCIONES DEL ÁREA DE DINÁMICA DE SISTEMAS (DS) PARA LA TEORÍA DE LA VISIÓN BASADA EN LOS RECURSOS (VBR)

O presente trabalho objetiva avaliar as contribuições conceituais da área de Dinâmica de Sistemas (DS) para a Teoria da Visão Baseada em Recursos (VBR), um campo de estudo da área de Estratégia. Para tanto, realizou-se um levantamento bibliográfico nos últimos anos na área de Estratégia e que contribuições a área de DS pode trazer neste contexto. Especificamente, é apresentada a arquitetura estratégica proposta por Warren (2002) que se utiliza dos dois conceitos para possibilitar análise das dependências entre os recursos e seus impactos dinâmicos no desempenho organizacional. Como resultado, pôde-se perceber que alguns aspectos não abordados pela VBR podem receber contribuições importantes provenientes da DS, como a oportunidade de construir modelos estratégicos que possibilitem a simulação, permitindo a análise da interdependência entre os recursos tangíveis e intangíveis, considerando não apenas o desempenho da empresa em um ponto no tempo, mas sua trajetória temporal e dinâmica. Pretende-se a partir deste trabalho, estender os estudos para aplicações dos seus resultados na área de ensino de estratégia, através de simuladores educacionais construídos com base nas duas áreas.This work aims to evaluate the conceptual contributions from the area of System Dynamics (SD) to the Resource Based-View (RBV) Theory, a field of study in the Strategy area. With that aim in mind, a literature review of the Strategy field in the latest years was carried out and the contributions that SD can offer in this context were analyzed. Specifically, the strategic architecture proposed by Warren (2002) is presented: it employs the two concepts to make the analysis of dependencies between resources and their dynamic impacts on organizational performance possible. As a result, it was observed that some aspects that are not addressed by the RBV theory can receive important contributions from SD, such as the opportunity to build strategic models that permit simulation, making the analysis of the interdependence between tangible and intangible resources possible, considering not only the performance of the company at a point in time, but its temporal trajectory and dynamics. This work, therefore, proposes to  extend the studies on the applications of its results in the Strategy teaching area, through the use of educational simulators which are based on those twoEl presente trabajo tiene como objetivo evaluar las contribuciones conceptuales del área de Dinámica de Sistemas (DS) para la Teoría de la Visión Basada en los Recursos (VBR), un campo de estudio del área de Estrategia. Para ello, se realizó un levantamiento bibliográfico de los últimos años en el área de Estrategia y que contribuciones el área de DS puede traer en este contexto. Específicamente, se presenta la arquitectura estratégica propuesta por Warren (2002) que utiliza los dos conceptos para posibilitar el análisis de las dependencias entre los recursos y sus impactos dinámicos en el desempeño organizacional. Como resultado, se puede percibir que algunos aspectos no abordados por la VBR pueden recibir contribuciones importantes provenientes de la DS, como la oportunidad de construir modelos estratégicos que posibiliten la simulación, permitiendo el análisis de la interdependencia entre los recursos tangibles e intangibles, considerando no apenas el desempeño de la empresa en un punto en el tiempo, sino su trayectoria temporal y dinámica. A partir de este trabajo, se pretende extender los estudios para aplicaciones de sus resultados en el área de la enseñanza de estrategia, a través de simuladores educacionales construidos con base en las dos áreas