المؤلفون: Richard Bauer, Dorina Haider, Aline Grempels, Rebecca Roscher, Stefanie Mauerer, Barbara Spellerberg

المصدر: Frontiers in Microbiology, Vol 14 (2023)

مصطلحات موضوعية: Streptococcus anginosus, CRISPR-Cas, classification, phylogenetic analysis, CSN2 gene, Microbiology, QR1-502

الوصف: Streptococcus anginosus is a commensal Streptococcal species that is often associated with invasive bacterial infections. However, little is known about its molecular genetic background. Many Streptococcal species, including S. anginosus, harbor clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems. A CRISPR-Cas type II-A system as well as a type II-C system have been reported for this species. To characterize the CRISPR-Cas type II systems of S. anginosus in more detail, we conducted a phylogenetic analysis of Cas9 sequences from CRISPR-Cas type II systems with a special focus on streptococci and S. anginosus. In addition, a phylogenetic analysis of S. anginosus strains based on housekeeping genes included in MLST analysis, was performed. All analyzed Cas9 sequences of S. anginosus clustered with the Cas9 sequences of CRISPR type II-A systems, including the Cas9 sequences of S. anginosus strains reported to harbor a type II-C system. The Cas9 genes of the CRISPR-Cas type II-C systems of other bacterial species separated into a different cluster. Moreover, analyzing the CRISPR loci found in S. anginosus, two distinct csn2 genes could be detected, a short form showing high similarity to the canonical form of the csn2 gene present in S. pyogenes. The second CRISPR type II locus of S. anginosus contained a longer variant of csn2 with close similarities to a csn2 gene that has previously been described in Streptococcus thermophilus. Since CRISPR-Cas type II-C systems do not contain a csn2 gene, the S. anginosus strains reported to have a CRISPR-Cas type II-C system appear to carry a variation of CRISPR-Cas type II-A harboring a long variant of csn2.

وصف الملف: electronic resource

العلاقة: https://www.frontiersin.org/articles/10.3389/fmicb.2023.1188671/fullTest; https://doaj.org/toc/1664-302XTest

الوصول الحر: https://doaj.org/article/6ee6dc3208aa4a589d60620138dba11bTest

المؤلفون: Ondra Petr, Lukas Grassner, Freda M. Warner, Michaela Dedeciusová, Richard Voldřich, Philipp Geiger, Konstantin Brawanski, Sina Gsellmann, Laura C. Meiners, Richard Bauer, Sascha Freigang, Michael Mokry, Alexandra Resch, Thomas Kretschmer, Tobias Rossmann, Francisco Ruiz Navarro, Harald Stefanits, Andreas Gruber, Mathias Spendel, Christoph Schwartz, Christoph Griessenauer, Franz Marhold, Camillo Sherif, Jonathan P. Wais, Karl Rössler, Jakob J. Zagata, Martin Ortler, Wolfgang Pfisterer, Manfred Mühlbauer, Felipe A. Trivik-Barrientos, Johannes Burtscher, Lukáš Krška, Radim Lipina, Martin Kerekanič, Jiří Fiedler, Petr Kasík, Vladimír Přibáň, Michal Tichý, Vladimír Beneš, Petr Krůpa, Tomáš Česák, Robert Kroupa, Andrej Callo, Pavel Haninec, Daniel Pohlodek, David Krahulík, Alena Sejkorová, Martin Sameš, Josef Dvořák, Andriana Juričeková, Pavel Buchvald, Robert Tomáš, Jan Klener, Vilém Juráň, Martin Smrčka, Petr Linzer, Miroslav Kaiser, Dušan Hrabovský, Radim Jančálek, John L. K. Kramer, Claudius Thomé, David Netuka

المصدر: Scientific Reports, Vol 12, Iss 1, Pp 1-10 (2022)

مصطلحات موضوعية: Medicine, Science

الوصف: Abstract Reflecting the first wave COVID-19 pandemic in Central Europe (i.e. March 16th–April 15th, 2020) the neurosurgical community witnessed a general diminution in the incidence of emergency neurosurgical cases, which was impelled by a reduced number of traumatic brain injuries (TBI), spine conditions, and chronic subdural hematomas (CSDH). This appeared to be associated with restrictions imposed on mobility within countries but also to possible delayed patient introduction and interdisciplinary medical counseling. In response to one year of COVID-19 experience, also mapping the third wave of COVID-19 in 2021 (i.e. March 16 to April 15, 2021), we aimed to reevaluate the current prevalence and outcomes for emergency non-elective neurosurgical cases in COVID-19-negative patients across Austria and the Czech Republic. The primary analysis was focused on incidence and 30-day mortality in emergency neurosurgical cases compared to four preceding years (2017–2020). A total of 5077 neurosurgical emergency cases were reviewed. The year 2021 compared to the years 2017–2019 was not significantly related to any increased odds of 30 day mortality in Austria or in the Czech Republic. Recently, there was a significant propensity toward increased incidence rates of emergency non-elective neurosurgical cases during the third COVID-19 pandemic wave in Austria, driven by their lower incidence during the first COVID-19 wave in 2020. Selected neurosurgical conditions commonly associated with traumatic etiologies including TBI, and CSDH roughly reverted to similar incidence rates from the previous non-COVID-19 years. Further resisting the major deleterious effects of the continuing COVID-19 pandemic, it is edifying to notice that the neurosurgical community´s demeanor to the recent third pandemic culmination keeps the very high standards of non-elective neurosurgical care alongside with low periprocedural morbidity. This also reflects the current state of health care quality in the Czech Republic and Austria.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2045-2322Test

الوصول الحر: https://doaj.org/article/54be7be993724df5a54c38503c56a3ccTest

المؤلفون: Verena Vogel, Richard Bauer, Stefanie Mauerer, Nicole Schiffelholz, Christian Haupt, Gerd M. Seibold, Marcus Fändrich, Paul Walther, Barbara Spellerberg

المصدر: Scientific Reports, Vol 11, Iss 1, Pp 1-16 (2021)

مصطلحات موضوعية: Medicine, Science

الوصف: Abstract As a conserved defense mechanism, many bacteria produce antimicrobial peptides, called bacteriocins, which provide a colonization advantage in a multispecies environment. Here the first bacteriocin of Streptococcus anginosus, designated Angicin, is described. S. anginosus is commonly described as a commensal, however it also possesses a high pathogenic potential. Therefore, understanding factors contributing to its host colonization and persistence are important. A radial diffusion assay was used to identify S. anginosus BSU 1211 as a potent bacteriocin producer. By genetic mutagenesis the background of bacteriocin production and the bacteriocin gene itself were identified. Synthetic Angicin shows high activity against closely related streptococci, listeria and vancomycin resistant enterococci. It has a fast mechanism of action and causes a membrane disruption in target cells. Angicin, present in cell free supernatant, is insensitive to changes in temperature from − 70 to 90 °C and pH values from 2 to 10, suggesting that it represents an interesting compound for potential applications in food preservation or clinical settings.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2045-2322Test

الوصول الحر: https://doaj.org/article/b730360628344a0f985b95b04ae34d00Test

المؤلفون: Richard Bauer, Katharina Hoenes, Tobias Meurle, Martin Hessling, Barbara Spellerberg

المصدر: Scientific Reports, Vol 11, Iss 1, Pp 1-11 (2021)

مصطلحات موضوعية: Medicine, Science

الوصف: Abstract Bacteria belonging to the group of ESKAPE pathogens are responsible for the majority of nosocomial infections. Due to the increase of antibiotic resistance, alternative treatment strategies are of high clinical relevance. In this context visible light as disinfection technique represents an interesting option as microbial pathogens can be inactivated without adjuvants. However cytotoxic effects of visible light on host cells have also been reported. We compared the cytotoxicity of violet and blue light irradiation on monocytic THP-1 and alveolar epithelium A549 cells with the inactivation effect on ESKAPE pathogens. THP-1 cells displayed a higher susceptibility to irradiation than A549 cells with first cytotoxic effects occurring at 300 J cm−2 (405 nm) and 400 J cm−2 (450 nm) in comparison to 300 J cm−2 and 1000 J cm−2, respectively. We could define conditions in which a significant reduction of colony forming units for all ESKAPE pathogens, except Enterococcus faecium, was achieved at 405 nm while avoiding cytotoxicity. Irradiation at 450 nm demonstrated a more variable effect which was species and medium dependent. In summary a significant reduction of viable bacteria could be achieved at subtoxic irradiation doses, supporting a potential use of visible light as an antimicrobial agent in clinical settings.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2045-2322Test

الوصول الحر: https://doaj.org/article/89986a72bb2d4e47837038b730de334fTest

المؤلفون: Armin Holch, Richard Bauer, Lia-Raluca Olari, Armando A. Rodriguez, Ludger Ständker, Nico Preising, Merve Karacan, Sebastian Wiese, Paul Walther, Yasser B. Ruiz-Blanco, Elsa Sanchez-Garcia, Christian Schumann, Jan Münch, Barbara Spellerberg

المصدر: Virulence, Vol 11, Iss 1, Pp 1402-1414 (2020)

مصطلحات موضوعية: ß2-microglobulin, antimicrobial peptides, innate immunity, ph, amyloid, Infectious and parasitic diseases, RC109-216

الوصف: The respiratory tract is a major entry site for microbial pathogens. To combat bacterial infections, the immune system has various defense mechanisms at its disposal, including antimicrobial peptides (AMPs). To search for novel AMPs from the respiratory tract, a peptide library from human broncho-alveolar-lavage (BAL) fluid was screened for antimicrobial activity by radial diffusion assays allowing the efficient detection of antibacterial activity within a small sample size. After repeated testing-cycles and subsequent purification, we identified ß-2-microglobulin (B2M) in antibacterially active fractions. B2M belongs to the MHC-1 receptor complex present at the surface of nucleated cells. It is known to inhibit the growth of Listeria monocytogenes and Escherichia coli and to facilitate phagocytosis of Staphylococcus aureus. Using commercially available B2M we confirmed a dose-dependent inhibition of Pseudomonas aeruginosa and L. monocytogenes. To characterize AMP activity within the B2M sequence, peptide fragments of the molecule were tested for antimicrobial activity. Activity could be localized to the C-terminal part of B2M. Investigating pH dependency of the antimicrobial activity of B2M demonstrated an increased activity at pH values of 5.5 and below, a hallmark of infection and inflammation. Sytox green uptake into bacterial cells following the exposure to B2M was determined and revealed a pH-dependent loss of bacterial membrane integrity. TEM analysis showed areas of disrupted bacterial membranes in L. monocytogenes incubated with B2M and high amounts of lysed bacterial cells. In conclusion, B2M as part of a ubiquitous cell surface complex may represent a potent antimicrobial agent by interfering with bacterial membrane integrity.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2150-5594Test; https://doaj.org/toc/2150-5608Test

الوصول الحر: https://doaj.org/article/f10bbf2e1585497dbe0729aeccdbea55Test

المؤلفون: Katharina Hoenes, Richard Bauer, Tobias Meurle, Barbara Spellerberg, Martin Hessling

المصدر: Frontiers in Microbiology, Vol 11 (2021)

مصطلحات موضوعية: visible light irradiation, photoinactivation, antimicrobial blue light, ESKAPE pathogens, non-pathogen, 405 nm, Microbiology, QR1-502

الوصف: Due to the globally observed increase in antibiotic resistance of bacterial pathogens and the simultaneous decline in new antibiotic developments, the need for alternative inactivation approaches is growing. This is especially true for the treatment of infections with the problematic ESKAPE pathogens, which include Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species, and often exhibit multiple antibiotic resistances. Irradiation with visible light from the violet and blue spectral range is an inactivation approach that does not require any additional supplements. Multiple bacterial and fungal species were demonstrated to be sensitive to this disinfection technique. In the present study, pathogenic ESKAPE organisms and non-pathogenic relatives are irradiated with visible blue and violet light with wavelengths of 450 and 405 nm, respectively. The irradiation experiments are performed at 37°C to test a potential application for medical treatment. For all investigated microorganisms and both wavelengths, a decrease in colony forming units is observed with increasing irradiation dose, although there are differences between the examined bacterial species. A pronounced difference can be observed between Acinetobacter, which prove to be particularly light sensitive, and enterococci, which need higher irradiation doses for inactivation. Differences between pathogenic and non-pathogenic bacteria of one genus are comparatively small, with the tendency of non-pathogenic representatives being less susceptible. Visible light irradiation is therefore a promising approach to inactivate ESKAPE pathogens with future fields of application in prevention and therapy.

وصف الملف: electronic resource

العلاقة: https://www.frontiersin.org/articles/10.3389/fmicb.2020.612367/fullTest; https://doaj.org/toc/1664-302XTest

الوصول الحر: https://doaj.org/article/d9c6271158374ef7b433d57732af135eTest

المؤلفون: Rüdiger Groß, Richard Bauer, Franziska Krüger, Elke Rücker-Braun, Lia-Raluca Olari, Ludger Ständker, Nico Preising, Armando A. Rodríguez, Carina Conzelmann, Fabian Gerbl, Daniel Sauter, Frank Kirchhoff, Benjamin Hagemann, Jasmina Gačanin, Tanja Weil, Yasser B. Ruiz-Blanco, Elsa Sanchez-Garcia, Wolf-Georg Forssmann, Annette Mankertz, Sabine Santibanez, Steffen Stenger, Paul Walther, Sebastian Wiese, Barbara Spellerberg, Jan Münch

المصدر: Frontiers in Microbiology, Vol 11 (2020)

مصطلحات موضوعية: placenta, AMP, hemoglobin fragment, proteolytic generation, antiviral, Microbiology, QR1-502

الوصف: The placenta acts as physical and immunological barrier against the transmission of viruses and bacteria from mother to fetus. However, the specific mechanisms by which the placenta protects the developing fetus from viral and bacterial pathogens are poorly understood. To identify placental peptides and small proteins protecting from viral and bacterial infections, we generated a peptide library from 10 kg placenta by chromatographic means. Screening the resulting 250 fractions against Herpes-Simplex-Virus 2 (HSV-2), which is rarely transmitted through the placenta, in a cell-based system identified two adjacent fractions with significant antiviral activity. Further rounds of chromatographic purification and anti-HSV-2 testing allowed to purify the bioactive peptide. Mass spectrometry revealed the presence of a 36-mer derived from the C-terminal region of the hemoglobin β subunit. The purified and corresponding chemically synthesized peptide, termed HBB(112–147), inhibited HSV-2 infection in a dose-dependent manner, with a mean IC50 in the median μg/ml range. Full-length hemoglobin tetramer had no antiviral activity. HBB(112–147) did not impair infectivity by direct targeting of the virions but prevented HSV-2 infection at the cell entry level. The peptide was inactive against Human Immunodeficiency Virus Type 1, Rubella and Zika virus infection, suggesting a specific anti-HSV-2 mechanism. Notably, HBB(112–147) has previously been identified as broad-spectrum antibacterial agent. It is abundant in placenta, reaching concentrations between 280 and 740 μg/ml, that are well sufficient to inhibit HSV-2 and prototype Gram-positive and -negative bacteria. We here additionally show, that HBB(112–147) also acts potently against Pseudomonas aeruginosa strains (including a multi-drug resistant strain) in a dose dependent manner, while full-length hemoglobin is inactive. Interestingly, the antibacterial activity of HBB(112–147) was increased under acidic conditions, a hallmark of infection and inflammatory conditions. Indeed, we found that HBB(112–147) is released from the hemoglobin precursor by Cathepsin D and Napsin A, acidic proteases highly expressed in placental and other tissues. We propose that upon viral or bacterial infection, the abundant hemoglobin precursor is proteolytically processed to release HBB(112–147), a broadly active antimicrobial innate immune defense peptide.

وصف الملف: electronic resource

العلاقة: https://www.frontiersin.org/article/10.3389/fmicb.2020.00508/fullTest; https://doaj.org/toc/1664-302XTest

الوصول الحر: https://doaj.org/article/ff9fddcb41054720a145b4fda2f63a19Test

المؤلفون: Katharina Hoenes, Richard Bauer, Barbara Spellerberg, Martin Hessling

المصدر: Antibiotics, Vol 10, Iss 3, p 341 (2021)

مصطلحات موضوعية: photoinactivation, antimicrobial blue light (aBL), reactive oxygen species (ROS), membrane damage, membrane permeabilization, 405 nm, Therapeutics. Pharmacology, RM1-950

الوصف: Interest in visible light irradiation as a microbial inactivation method has widely increased due to multiple possible applications. Resistance development is considered unlikely, because of the multi-target mechanism, based on the induction of reactive oxygen species by wavelength specific photosensitizers. However, the affected targets are still not completely identified. We investigated membrane integrity with the fluorescence staining kit LIVE/DEAD® BacLight™ on a Gram positive and a Gram negative bacterial species, irradiating Staphylococcus carnosus and Pseudomonas fluorescens with 405 nm and 450 nm. To exclude the generation of viable but nonculturable (VBNC) bacterial cells, we applied an ATP test, measuring the loss of vitality. Pronounced uptake of propidium iodide was only observed in Pseudomonas fluorescens at 405 nm. Transmission electron micrographs revealed no obvious differences between irradiated samples and controls, especially no indication of an increased bacterial cell lysis could be observed. Based on our results and previous literature, we suggest that visible light photoinactivation does not lead to rapid bacterial cell lysis or disruption. However, functional loss of membrane integrity due to depolarization or inactivation of membrane proteins may occur. Decomposition of the bacterial envelope following cell death might be responsible for observations of intracellular component leakage.

وصف الملف: electronic resource

العلاقة: https://www.mdpi.com/2079-6382/10/3/341Test; https://doaj.org/toc/2079-6382Test

الوصول الحر: https://doaj.org/article/c89a2e68f68d449c95faeccfec3b7117Test

المؤلفون: Fern Van Sant, Sayed M Hassan, Drury Reavill, Rita McManamon, Elizabeth W Howerth, Mauricio Seguel, Richard Bauer, Kathy M Loftis, Christopher R Gregory, Paula G Ciembor, Branson W Ritchie

المصدر: PLoS ONE, Vol 14, Iss 3, p e0213248 (2019)

مصطلحات موضوعية: Medicine, Science

الوصف: During 2018, four free-ranging conures, from a naturalized flock in San Francisco, presented with a characteristic set of neurologic signs that had been reported in other individuals from this flock. The cause of morbidity or mortality in historic cases has not been identified. From these four subjects, fresh feces were collected during their initial days of hospitalization and submitted to the University of Georgia Infectious Diseases Laboratory and Center for Applied Isotope Studies for bromethalin and desmethyl-bromethalin quantitation. Using High Performance Liquid Chromatography, the laboratory detected bromethalin, a non-anticoagulant, single-dose rodenticide, in fecal samples from three subjects; half of these samples were also positive for desmethyl-bromethalin, bromethalin's active metabolite. In three subjects that died, the UGA laboratory screened brain and liver samples and found bromethalin in all samples; desmethyl-bromethalin was detected in all but one brain sample, which was below the detection limit. Our findings suggest the conures are more resistant to bromethalin than are other species in which bromethalin has been studied, and/or that the conures may be ingesting the toxin at a sublethal dose. More data is needed to better assess the long-term effects of bromethalin on animals exposed at the subacute/chronic levels, and also to better understand the compartmentalization of bromethalin and desmethyl-bromethalin in a wider variety of species.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1932-6203Test

الوصول الحر: https://doaj.org/article/3289a5bf1b314b65a10ae5c4281841adTest

المؤلفون: Puja Yadav, Shalini Verma, Richard Bauer, Monika Kumari, Meenakshi Dua, Atul Kumar Johri, Vikas Yadav, Barbara Spellerberg

المصدر: Microorganisms, Vol 8, Iss 11, p 1835 (2020)

مصطلحات موضوعية: streptococci, opportunistic pathogen, planktonic, biofilm, antibiotic therapy, quorum sensing (QS), Biology (General), QH301-705.5

الوصف: Streptococci are a diverse group of bacteria, which are mostly commensals but also cause a considerable proportion of life-threatening infections. They colonize many different host niches such as the oral cavity, the respiratory, gastrointestinal, and urogenital tract. While these host compartments impose different environmental conditions, many streptococci form biofilms on mucosal membranes facilitating their prolonged survival. In response to environmental conditions or stimuli, bacteria experience profound physiologic and metabolic changes during biofilm formation. While investigating bacterial cells under planktonic and biofilm conditions, various genes have been identified that are important for the initial step of biofilm formation. Expression patterns of these genes during the transition from planktonic to biofilm growth suggest a highly regulated and complex process. Biofilms as a bacterial survival strategy allow evasion of host immunity and protection against antibiotic therapy. However, the exact mechanisms by which biofilm-associated bacteria cause disease are poorly understood. Therefore, advanced molecular techniques are employed to identify gene(s) or protein(s) as targets for the development of antibiofilm therapeutic approaches. We review our current understanding of biofilm formation in different streptococci and how biofilm production may alter virulence-associated characteristics of these species. In addition, we have summarized the role of surface proteins especially pili proteins in biofilm formation. This review will provide an overview of strategies which may be exploited for developing novel approaches against biofilm-related streptococcal infections.

وصف الملف: electronic resource

العلاقة: https://www.mdpi.com/2076-2607/8/11/1835Test; https://doaj.org/toc/2076-2607Test

الوصول الحر: https://doaj.org/article/08aa2d1d750e4521918206dddad8e9faTest