Regulation of Biofilm Formation by σB is a Common Mechanism in Staphylococcus Epidermidis and is not Mediated by Transcriptional Regulation of sarA

2009 ◽  
Vol 32 (9) ◽  
pp. 584-591 ◽  
Author(s):  
Sebastian JÄger ◽  
Beate Jonas ◽  
Dorothea Pfanzelt ◽  
Matthias A. Horstkotte ◽  
Holger Rohde ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Film Formation ◽  
Transcriptional Analysis ◽  
Common Mechanism ◽  
Minor Role ◽  
Regulatory Pathway ◽  
Pathogenetic Factor ◽  
A Minor ◽  
The Impact

Biofilm formation is a major pathogenetic factor of Staphylococcus epidermidis. In S. epidermidis the alternative sigma factor σB was identified to regulate biofilm formation in S. epidermidis 1457. In S. aureus σB dependent regulation plays a minor role, whereas sarA (Staphylococcus accessory regulator) is an essential regulator. Therefore, we investigated the impact of σB on sarA transcription and biofilm formation in three independent S. epidermidis isolates. Mutants with dysfunctional σB displayed a strongly reduced biofilm formation, whereas in mutants with constitutive σB activity bio film formation was increased. Transcriptional analysis revealed that IcaA transcription was down-regulated in all σB negative mutants while icaR transcription was up-regulated. However, transcriptional differences varied between individual strains, indicating that additional σB-dependent regulators are involved in biofilm expression. Interestingly, despite the presence of a σB promoter beside two σA promoters no differences, or only minor ones, were observed in sarA transcription, indicating that σB-dependent sarA transcript has no influence on the phenotypic changes. The data observed in independent clinical S. epidermidis isolates suggests that, in contrast to S. aureus, regulation of biofilm formation by σB is a general feature in S. epidermidis. Additionally, we were able to demonstrate that the sarA- dependent regulation is not involved in this regulatory pathway.

scholarly journals mazEF Homologue Has a Minor Role in Staphylococcus epidermidis 1457 Virulence Potential

2022 ◽  
Vol 11 ◽  
Author(s):  
Vânia Gaio ◽  
Tânia Lima ◽  
Manuel Vilanova ◽  
Nuno Cerca ◽  
Angela França
Keyword(s):  
Immune System ◽  
Immune Cells ◽  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Minor Role ◽  
Host Immune System ◽  
Vbnc State ◽  
Virulence Potential ◽  
Previous Hypothesis ◽  
A Minor

Staphylococcus epidermidis biofilm cells are characterized by increased antimicrobial tolerance and improved ability to evade host immune system defenses. These features are, in part, due to the presence of viable but non-culturable (VBNC) cells. A previous study identified genes potentially involved in VBNC cells formation in S. epidermidis biofilms, among which SERP1682/1681 raised special interest due to their putative role as a toxin–antitoxin system of the mazEF family. Herein, we constructed an S. epidermidis mutant lacking the mazEF genes homologues and determined their role in (i) VBNC state induction during biofilm formation, (ii) antimicrobial susceptibility, (iii) survival in human blood and plasma, and (iv) activation of immune cells. Our results revealed that mazEF homologue did not affect the proportion of VBNC cells in S. epidermidis 1457, refuting the previous hypothesis that mazEF homologue could be linked with the emergence of VBNC cells in S. epidermidis biofilms. Additionally, mazEF homologue did not seem to influence key virulence factors on this strain, since its deletion did not significantly affect the mutant biofilm formation capacity, antimicrobial tolerance or the response by immune cells. Surprisingly, our data suggest that mazEF does not behave as a toxin–antitoxin system in S. epidermidis strain 1457, since no decrease in the viability and culturability of bacteria was found when only the mazF toxin homologue was being expressed.

scholarly journals Impact of Bacterial Biofilm Formation on In Vitro and In Vivo Activities of Antibiotics

1998 ◽  
Vol 42 (4) ◽  
pp. 895-898 ◽  
Author(s):  
Silvia Schwank ◽  
Zarko Rajacic ◽  
Werner Zimmerli ◽  
Jürg Blaser
Keyword(s):  
Animal Model ◽  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Bacterial Biofilm ◽  
Phenotypic Resistance ◽  
Vitro Model ◽  
The Impact ◽  
Isogenic Strains

ABSTRACT The impact of bacterial adherence on antibiotic activity was analyzed with two isogenic strains of Staphylococcus epidermidis that differ in the features of their in vitro biofilm formation. The eradication of bacteria adhering to glass beads by amikacin, levofloxacin, rifampin, or teicoplanin was studied in an animal model and in a pharmacokinetically matched in vitro model. The features of S. epidermidis RP62A that allowed it to grow on surfaces in multiple layers promoted phenotypic resistance to antibiotic treatment, whereas strain M7 failed to accumulate, despite initial adherence on surfaces and growth in suspension similar to those for RP62A. Biofilms of S. epidermidis M7 were better eradicated than those of strain RP62A in vitro (46 versus 31%;P < 0.05) as well as in the animal model (39 versus 9%; P < 0.01).

scholarly journals Extracellular Pneumococcal Serine Proteases Affect Nasopharyngeal Colonization

2021 ◽  
Vol 10 ◽  
Author(s):  
Murtadha Q. Ali ◽  
Thomas P. Kohler ◽  
Gerhard Burchhardt ◽  
Andreas Wüst ◽  
Nadin Henck ◽  
...  
Keyword(s):  
Serine Proteases ◽  
Bacterial Load ◽  
Acute Infection ◽  
Minor Role ◽  
Extracellular Proteases ◽  
Nasopharyngeal Colonization ◽  
Invasive Diseases ◽  
Pneumococcal Colonization ◽  
A Minor ◽  
The Impact

Streptococcus pneumoniae has evolved versatile strategies to colonize the nasopharynx of humans. Colonization is facilitated by direct interactions with host cell receptors or via binding to components of the extracellular matrix. In addition, pneumococci hijack host-derived extracellular proteases such as the serine protease plasmin(ogen) for ECM and mucus degradation as well as colonization. S. pneumoniae expresses strain-dependent up to four serine proteases. In this study, we assessed the role of secreted or cell-bound serine proteases HtrA, PrtA, SFP, and CbpG, in adherence assays and in a mouse colonization model. We hypothesized that the redundancy of serine proteases compensates for the deficiency of a single enzyme. Therefore, double and triple mutants were generated in serotype 19F strain EF3030 and serotype 4 strain TIGR4. Strain EF3030 produces only three serine proteases and lacks the SFP encoding gene. In adherence studies using Detroit-562 epithelial cells, we demonstrated that both TIGR4Δcps and 19F mutants without serine proteases or expressing only CbpG, HtrA, or PrtA have a reduced ability to adhere to Detroit-562 cells. Consistent with these results, we show that the mutants of strain 19F, which preferentially colonizes mice, abrogate nasopharyngeal colonization in CD-1 mice after intranasal infection. The bacterial load in the nasopharynx was monitored for 14 days. Importantly, mutants showed significantly lower bacterial numbers in the nasopharynx two days after infection. Similarly, we detected a significantly reduced pneumococcal colonization on days 3, 7, and 14 post-inoculations. To assess the impact of pneumococcal serine proteases on acute infection, we infected mice intranasally with bioluminescent and invasive TIGR4 or isogenic triple mutants expressing only CbpG, HtrA, PrtA, or SFP. We imaged the acute lung infection in real-time and determined the survival of the mice. The TIGR4lux mutant expressing only PrtA showed a significant attenuation and was less virulent in the acute pneumonia model. In conclusion, our results showed that pneumococcal serine proteases contributed significantly to pneumococcal colonization but played only a minor role in pneumonia and invasive diseases. Because colonization is a prerequisite for invasive diseases and transmission, these enzymes could be promising candidates for the development of antimicrobials to reduce pneumococcal transmission.

scholarly journals Low incidence of Schmallenberg virus infection in natural cases of abortion in domestic ruminants in Hungary

2020 ◽  
Vol 68 (1) ◽  
pp. 105-111
Author(s):  
Levente Szeredi ◽  
Ádám Dán ◽  
Péter Malik ◽  
Szilárd Jánosi ◽  
Ákos Hornyák
Keyword(s):  
Tissue Sample ◽  
Schmallenberg Virus ◽  
Minor Role ◽  
Chain Reaction ◽  
Domestic Ruminants ◽  
Polymerase Chain ◽  
Low Incidence ◽  
A Minor ◽  
The Impact

AbstractAn epizootic caused by a new orthobunyavirus called Schmallenberg virus (SBV) was recognised in European ruminants in 2011 and 2012. The re-emergence of the infection was reported in several countries in the subsequent years. Although the main clinical sign of SBV infection is abortion, the impact of SBV in natural cases of abortion in domestic ruminants had not been systematically examined before this study. The aim of the study was to investigate the role of SBV infection and to compare it to the importance of other causes of abortion by examining 537 natural cases of abortion that had occurred between 2011 and 2017 in Hungary. The cause of abortion was determined in 165 (31%) cases. An infectious cause was proved in 88 (16%) cases. SBV infection was found only in a total of four cases (0.8%) using real-time polymerase chain reaction. Three of them proved to be inapparent SBV infection, and one case was attributed to SBV-induced abortion by detecting non-purulent encephalitis and SBV nucleoprotein by immunohistochemistry in a brain tissue sample. According to the results, SBV played a minor role in natural cases of domestic ruminant abortion in Hungary during the 7-year period following the first SBV outbreak in 2011.

scholarly journals Hope, Disillusion and Coincidence in Migratory Decisions by Senegalese Migrants in Brazil

2021 ◽  
Vol 9 (1) ◽  
pp. 268-277
Author(s):  
Philipp Roman Jung
Keyword(s):  
Minor Role ◽  
Positive Outcomes ◽  
Essential Characteristic ◽  
New Destinations ◽  
Onward Migration ◽  
Decisions To Leave ◽  
Restricted Mobility ◽  
A Minor ◽  
The Impact ◽  
Do So

Uncertainty is an essential characteristic of our lives. However, by moving from one country to another, from a familiar context to an unfamiliar one, uncertainty becomes a key element of migrants’ decisions. In times of restricted mobility regimes, migrants often do not know if they will be able to reach the desired destination. Even if they manage to do so, it is still uncertain if they will be able to fulfil their aspirations. However, uncertainty also leaves room for hope. Departing from the conceptualisation of hope as the simultaneity of both potentiality and uncertainty and from the concept of circumstantial migration, this article analyses (1) retrospectively the decision of Senegalese migrants to move to Brazil and (2) the intentions of onward migration. Based on empirical data collected through ethnographic fieldwork in four Brazilian cities, this article shows how migration as a form of social hope is redirected to new destinations and that this redirection is a consequence of circumstances and coincidences, which enable or prevent movement. Potential positive outcomes of migration outweighed negative ones, which play a minor role and hardly affect decisions to leave Senegal. However, decisions to emigrate are often based on incomplete information and ill-informed expectations regarding the circumstances at the destination and can lead to feelings of disillusion. The impact of uncertainties shows a more differentiated picture in the context of onward migration intentions. While some migrants are willing to take big risks in onward migration, others try to minimize uncertainties.

scholarly journals Health and culture: National and individual drivers of preference for professional medical help

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
I Leijen ◽  
H van Herk
Keyword(s):  
Personal Values ◽  
International Health ◽  
Health Care Research ◽  
Minor Role ◽  
Healthcare Use ◽  
Country Level ◽  
Country Culture ◽  
Self Transcendence ◽  
A Minor ◽  
The Impact

Abstract Background Preferences for professional medical healthcare in case of non-acute medical situations influence a major amount of healthcare use, and vary strongly across countries. Personal values and country culture have been shown to be important predictors of human preferences in many areas. We therefore investigated the impact of both individual and country-level characteristics across Europe on individual healthcare preferences related to non-acute medical conditions. Methods Data from 17,710 individuals from 16 European countries were analysed using a multi-level approach, simultaneously including individual- and country level predictors. Results Healthcare preferences were explained by both human values (Conservation γ = 0.097, p &lt; .01, Self Enhancement γ = 0.038, p &lt; .05) and trust in the doctor (γ 0.054, p &lt; .01). Socio-demographics played a minor role. Societal tightness-looseness (TL) strongly predicted healthcare use preferences on the country level (γ 0.109, p &lt; .05). Also TL enhanced the relation between conservation and preference (γ 0.024, p &lt;.05), and decreased the relation between self-enhancement and preference (γ -0.021, p &lt;.01). Conclusions Our results suggest that healthcare behavior is related to people's motivations and the extent to which the society they live in is more tight or loose. Stronger conservation values increase preference for professional medical care, while self-transcendence- and openness-to-change values decrease preference. Societal tightness is positively related to preference on the country level. Furthermore, in tight societies the effect of conservation is enhanced and the effect of self enhancement is suppressed, related to an additional higher preference for professional medical help. Our results may help key actors within the health system to predict and channel healthcare choice behavior across and within nations. Key messages Culture plays an important role in developing a preference for medical help, on both individual as well as country level. Personal values the as well as cultural tightness looseness are fruitful tools for the analysis of national and international health care research.

Do Prosody and Embodiment Influence the Perceived Naturalness of Conversational Agents’ Speech?

2021 ◽  
Vol 18 (4) ◽  
pp. 1-15
Author(s):  
Jonathan Ehret ◽  
Andrea Bönsch ◽  
Lukas Aspöck ◽  
Christine T. Röhr ◽  
Stefan Baumann ◽  
...  
Keyword(s):  
Masking Effect ◽  
Minor Role ◽  
Virtual Agents ◽  
Conversational Agents ◽  
Virtual Agent ◽  
Online Study ◽  
Human Voice ◽  
The One ◽  
A Minor ◽  
The Impact

For conversational agents’ speech, either all possible sentences have to be prerecorded by voice actors or the required utterances can be synthesized. While synthesizing speech is more flexible and economic in production, it also potentially reduces the perceived naturalness of the agents among others due to mistakes at various linguistic levels. In our article, we are interested in the impact of adequate and inadequate prosody, here particularly in terms of accent placement, on the perceived naturalness and aliveness of the agents. We compare (1) inadequate prosody, as generated by off-the-shelf text-to-speech (TTS) engines with synthetic output; (2) the same inadequate prosody imitated by trained human speakers; and (3) adequate prosody produced by those speakers. The speech was presented either as audio-only or by embodied, anthropomorphic agents, to investigate the potential masking effect by a simultaneous visual representation of those virtual agents. To this end, we conducted an online study with 40 participants listening to four different dialogues each presented in the three Speech levels and the two Embodiment levels. Results confirmed that adequate prosody in human speech is perceived as more natural (and the agents are perceived as more alive) than inadequate prosody in both human (2) and synthetic speech (1). Thus, it is not sufficient to just use a human voice for an agents’ speech to be perceived as natural—it is decisive whether the prosodic realisation is adequate or not. Furthermore, and surprisingly, we found no masking effect by speaker embodiment, since neither a human voice with inadequate prosody nor a synthetic voice was judged as more natural, when a virtual agent was visible compared to the audio-only condition. On the contrary, the human voice was even judged as less “alive” when accompanied by a virtual agent. In sum, our results emphasize, on the one hand, the importance of adequate prosody for perceived naturalness, especially in terms of accents being placed on important words in the phrase, while showing, on the other hand, that the embodiment of virtual agents plays a minor role in the naturalness ratings of voices.

Investigating L1 lay assessments of L2 French pronunciation

2018 ◽  
Vol 4 (1) ◽  
pp. 103-128 ◽  
Author(s):  
Kerry Lappin-Fortin
Keyword(s):  
Qualitative Data ◽  
Native Speaker ◽  
Minor Role ◽  
Strong Correlations ◽  
Rate Of Speech ◽  
A Minor ◽  
The Impact ◽  
English Canadian ◽  
Larger Sample

Abstract This study examined how 10 English Canadian students reading a 122-word passage in French were assessed by a diverse group of 40 native speaker lay listeners in France, thus addressing a lacuna in current pronunciation research. Both stimulus factors and listener effects were investigated. Quantitative and qualitative data revealed strong correlations between perceptions of accentedness and comprehensibility, and between lay ratings and those made by two experts. Results highlighted the impact phonemic errors and rate of speech have on rater judgments, while linkings (liaisons) and other prosodic elements seemed to play a minor role. Recommendations are made for a follow-up study using a larger sample.

scholarly journals Biofilm Formation by Staphylococcus epidermidis Depends on Functional RsbU, an Activator of thesigB Operon: Differential Activation Mechanisms Due to Ethanol and Salt Stress

2001 ◽  
Vol 183 (8) ◽  
pp. 2624-2633 ◽  
Author(s):  
Johannes K.-M. Knobloch ◽  
Katrin Bartscht ◽  
Axel Sabottke ◽  
Holger Rohde ◽  
Heinz-Hubert Feucht ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Fragment Length Polymorphism ◽  
Insertion Site ◽  
Alternative Sigma Factor ◽  
Polysaccharide Intercellular Adhesin ◽  
Wild Type ◽  
Activation Mechanisms ◽  
Pathogenetic Factor ◽  
Negative Phenotype

ABSTRACT Staphylococcus epidermidis is a common pathogen in medical device-associated infections. Its major pathogenetic factor is the ability to form adherent biofilms. The polysaccharide intercellular adhesin (PIA), which is synthesized by the products of theicaADBC gene cluster, is essential for biofilm accumulation. In the present study, we characterized the gene locus inactivated by Tn917 insertions of two isogenic,icaADBC-independent, biofilm-negative mutants, M15 and M19, of the biofilm-producing bacterium S. epidermidis 1457. The insertion site was the same in both of the mutants and was located in the first gene, rsbU, of an operon highly homologous to thesigB operons of Staphylococcus aureus andBacillus subtilis. Supplementation of Trypticase soy broth with NaCl (TSBNaCl) or ethanol (TSBEtOH), both of which are known activators of sigB, led to increased biofilm formation and PIA synthesis by S. epidermidis 1457. Insertion of Tn917 into rsbU, a positive regulator of alternative sigma factor ςB, led to a biofilm-negative phenotype and almost undetectable PIA production. Interestingly, in TSBEtOH, the mutants were enabled to form a biofilm again with phenotypes similar to those of the wild type. In TSBNaCl, the mutants still displayed a biofilm-negative phenotype. No difference in primary attachment between the mutants and the wild type was observed. Similar phenotypic changes were observed after transfer of the Tn917 insertion of mutant M15 to the independent and biofilm-producing strain S. epidermidis8400. In 11 clinical S. epidermidis strains, a restriction fragment length polymorphism of the sigB operon was detected which was independent of the presence of theicaADBC locus and a biofilm-positive phenotype. Obviously, different mechanisms are operative in the regulation of PIA expression in stationary phase and under stress induced by salt or ethanol.

A Harmonic Balance Technique for Multistage Turbomachinery Applications

2014 ◽  
Author(s):  
Christian Frey ◽  
Graham Ashcroft ◽  
Hans-Peter Kersken ◽  
Christian Voigt
Keyword(s):  
Harmonic Balance ◽  
Simulation Method ◽  
Minor Role ◽  
Frequency Domain Method ◽  
Nonlinear Frequency ◽  
Flow Solver ◽  
Fundamental Frequencies ◽  
Interaction Terms ◽  
A Minor ◽  
The Impact

This article describes a nonlinear frequency domain method for the simulation of unsteady blade row interaction problems across several blade rows in turbomachinery. The capability to efficiently simulate such interactions is crucial for the improvement of the prediction of blade vibrations, tonal noise, and the impact of unsteadiness on aerodynamic performance. The simulation technique presented here is based on the harmonic balance approach and has been integrated into an existing flow solver. A nontrivial issue in the application of harmonic balance methods to turbomachinery flows is the fact that various fundamental frequencies may occur simultaneously in one relative system, each one being due to the interaction of two blade rows. It is shown that, considering the disturbances corresponding to different fundamental frequencies as mutually uncoupled, one can develop an unsteady simulation method which from a practial view point turns out to be highly attractive. On the one hand, it is possible to take into account arbitrarily many nonlinear interaction terms. On the other, the computational efficiency can be increased considerably once it is known that the nonlinear coupling between certain subsets of the harmonics plays only a minor role. To validate the method and demonstrate its accuracy and efficiency a multistage compressor configuration is simulated using both the method described in this article and a conventional time-domain solver.

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