Publications by authors named "Willem J B van Wamel"

The single most common microbe causing cardiovascular infections is (). produces coagulase that converts fibrinogen to fibrin, which is incorporated into biofilms. This process aids in adherence to intravascular structures, defense against the host immune system, and resistance to antimicrobial treatment.

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Burn wounds are a major burden, with high mortality rates due to infections. is a major causative agent of burn wound infections, which can be difficult to treat because of antibiotic resistance and biofilm formation. An alternative to antibiotics is the use of bacteriophages, viruses that infect and kill bacteria.

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Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) infections impose a considerable burden on health systems, yet there is remarkable variation in the global incidence and epidemiology of MRSA. The MACOTRA consortium aimed to identify bacterial markers of epidemic success of MRSA isolates in Europe using a representative MRSA collection originating from France, the Netherlands and the United Kingdom.

Methods: Operational definitions of success were defined in consortium meetings to compose a balanced strain collection of successful and sporadic MRSA isolates.

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Infections involving antibiotic resistant () represent a major challenge to successful treatment. Further, although bacteriophages (phages) could be an alternative to antibiotics, there exists a lack of correlation in phage susceptibility results between conventional in vitro and in vivo assays. This discrepancy may hinder the potential implementation of bacteriophage therapy.

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Bacterial survival on, and interactions with, human skin may explain the epidemiological success of MRSA strains. We evaluated the bacterial counts for 27 epidemic and 31 sporadic MRSA strains on 3D epidermal models based on N/TERT cells (NEMs) after 1, 2 and 8 days. In addition, the expression of antimicrobial peptides (hBD-2, RNase 7), inflammatory cytokines (IL-1, IL-6) and chemokine IL-8 by NEMs was assessed using immunoassays and the expression of 43 virulence factors was determined by a multiplex competitive Luminex assay.

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Methicillin-resistant Staphylococcus aureus (MRSA) clusters are considered epidemic or nonepidemic based on their ability to spread effectively. Successful transmission could be influenced by dehydration tolerance. Current methods for determination of dehydration tolerance lack accuracy.

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Bacteria encased in a biofilm poses significant challenges to successful treatment, since both the immune system and antibiotics are ineffective. Sonobactericide, which uses ultrasound and microbubbles, is a potential new strategy for increasing antimicrobial effectiveness or directly killing bacteria. Several studies suggest that sonobactericide can lead to bacterial dispersion or sonoporation (i.

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Biofilm-associated infections with Staphylococcus aureus are difficult to treat even after administration of antibiotics that according to the standard susceptibility assays are effective. Currently, the assays used in the clinical laboratories to determine the sensitivity of S. aureus towards antibiotics are not representing the behaviour of biofilm-associated S.

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Bacterial biofilms are a huge burden on our healthcare systems worldwide. The lack of specificity in diagnostic and treatment possibilities result in difficult-to-treat and persistent infections. The aim of this in vitro study was to investigate if microbubbles targeted specifically to bacteria in biofilms could be used both for diagnosis as well for sonobactericide treatment and demonstrate their theranostic potential for biofilm infection management.

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Saliva is a matrix which may act as a vector for pathogen transmission and may serve as a possible proxy for SARS-CoV-2 contagiousness. Therefore, the possibility of detection of intracellular SARS-CoV-2 in saliva by means of fluorescence in situ hybridization is tested, utilizing probes targeting the antisense or sense genomic RNA of SARS-CoV-2. This method was applied in a pilot study with saliva samples collected from healthy persons and those presenting with mild or moderate COVID-19 symptoms.

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Staphylococcus aureus biofilms are a major problem in modern healthcare due to their resistance to immune system defenses and antibiotic treatments. Certain analgesic agents are able to modulate S. aureus biofilm formation, but currently no evidence exists if paracetamol, often combined with antibiotic treatment, also has this effect.

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Pneumonia is an acute pulmonary infection associated with high mortality and an immense financial burden on healthcare systems. is an opportunistic pathogen capable of inducing pneumonia (SAP), with some lineages also showing multidrug resistance. Given the high level of antibiotic resistance, much research has been focused on targeting virulence factors, including toxins and biofilm-associated proteins, in an attempt to develop effective SAP therapeutics.

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In hospitals, Verona Integron-encoded Metallo-beta-lactamase (VIM)-positive Pseudomonas aeruginosa may colonize sink drains, and from there, be transmitted to patients. These hidden reservoirs are difficult to eradicate since P. aeruginosa forms biofilms that resist disinfection.

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and are related species which can cause predominantly acute and subacute infections, respectively. Differences in human adaptive immune responses to these two species are not well understood. Dendritic cells (DCs) have an important role in the control and regulation of anti-staphylococcal T cell responses.

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Ultrasound has been developed as both a diagnostic tool and a potent promoter of beneficial bio-effects for the treatment of chronic bacterial infections. Bacterial infections, especially those involving biofilm on implants, indwelling catheters and heart valves, affect millions of people each year, and many deaths occur as a consequence. Exposure of microbubbles or droplets to ultrasound can directly affect bacteria and enhance the efficacy of antibiotics or other therapeutics, which we have termed sonobactericide.

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extracellular DNA (eDNA) plays a crucial role in the structural stability of biofilms during bacterial colonization; on the contrary, host immune responses can be induced by bacterial eDNA. Previously, we observed production of thermonuclease during the early stages of biofilm formation in a mammalian cell culture medium. Using a fluorescence resonance energy transfer (FRET)-based assay, we detected thermonuclease activity of biofilms grown in Iscove's modified Dulbecco's medium (IMDM) earlier than that of widely studied biofilms grown in tryptic soy broth (TSB).

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Immune modulators are known to be produced by matured biofilms and during different stages of planktonic growth of Little is known about immune modulator production during the early stages of biofilm formation, thus raising the following question: how does protect itself from the innate immune responses at these stages? Therefore, we determined the production of the following immune modulators: chemotaxis inhibitory protein of staphylococci (CHIPS); staphylococcal complement inhibitor (SCIN); formyl peptide receptor-like 1 inhibitor; gamma-hemolysin component B; leukocidins D, E, and S; staphylococcal superantigen-like proteins 1, 3, 5, and 9; and staphylococcal enterotoxin A. Production was determined during biofilm formation in Iscove's modified Dulbecco's medium at different time points using a competitive Luminex assay and mass spectrometry. Both methods demonstrated the production of the immune modulators SCIN and CHIPS during the early stages of biofilm formation.

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Article Synopsis
  • The study investigates the use of rhesus macaques as a model for examining the colonization and eradication of S. aureus, comparing it to existing human models which pose safety concerns.
  • Animals were screened for nasal S. aureus carriage, with 20 selected for a decolonization experiment using mupirocin alone or a combination treatment over 5 days.
  • Results showed that 11 of the 20 animals successfully became culture-negative for S. aureus, and upon subsequent inoculation, a short-term presence of the strain was noted in some, suggesting the macaque model could be effective for further research into S. aureus treatments.
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Article Synopsis
  • The study focuses on the fibronectin-binding protein A (FnBPA), which is vital for bacterial adherence to human tissues and plays a role in disease severity.
  • Researchers identified five different isotypes of FnBPA A domain in clinical samples from patients with bacteremia and measured their immune response via IgG levels.
  • Despite observing some IgG production against FnBPA, significant increases were noted in only 14% of patients, highlighting gaps in understanding how sequence diversity in this protein affects human antibody responses during infections.
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Infective endocarditis (IE) is associated with high morbidity and mortality rates. The predominant bacteria causing IE is Staphylococcus aureus (S. aureus), which can bind to existing thrombi on heart valves and generate vegetations (biofilms).

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are strong inducers of neutrophil extracellular traps (NETs), a defense mechanism of neutrophils against pathogens. Our aim was to explore the role of Protein A in -induced NETosis. We determined the Protein A production of four different strains and found a direct relationship between the degree of NETosis induction and Protein A production: strains producing higher concentrations of Protein A evoke significantly more NETs.

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Article Synopsis
  • The study investigates the relationship between genetic variations of S. aureus bacteria and two forms of anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis: PR3-positive granulomatosis with polyangiitis (GPA) and MPO-positive AAV.
  • Results suggest that while both patient groups mainly carry S. aureus types common in the general population, there are distinct genetic differences in isolates associated with MPO-ANCA.
  • The findings point to specific genetic traits of S. aureus, such as pore-forming toxins, that may influence disease progression and immune responses in patients, and challenge previous beliefs about the role of superantigens.
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Surface-exposed proteins of pathogenic bacteria play a critical role during infections . The vast majority of these molecules are able to trigger strong immune responses. Measuring the humoral immune response against pathogenic bacteria through less-time consuming tests is necessary to reduce the window time for the diagnosis of diseases that may be associated with high morbidity and mortality rates.

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The spread of multidrug-resistant Staphylococcus aureus strains, including methicillin-resistant S. aureus (MRSA), has shortened the useful life of anti-staphylococcal drugs enormously. Two approaches can be followed to address this problem: screening various sources for new leads for antibiotics or finding ways to disable the resistance mechanisms to existing antibiotics.

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Background: Multiple inducers of in vitro Neutrophil Extracellular Trap (NET) formation (NETosis) have been described. Since there is much variation in study design and results, our aim was to create a systematic review of NETosis inducers and perform a standardized in vitro study of NETosis inducers important in (cardiac) wound healing.

Methods: In vitro NETosis was studied by incubating neutrophils with PMA, living and dead bacteria (S.

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