Publications by authors named "Barbara Spellerberg"

61 Publications

Group B streptococcal colonization in elderly women.

BMC Infect Dis 2021 May 3;21(1):408. Epub 2021 May 3.

Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3010, Bern, Switzerland.

Background: In non-pregnant adults, the incidence of invasive Group B Streptococcus (GBS) disease is continuously increasing. Elderly and immunocompromised persons are at increased risk of infection. GBS commonly colonizes the vaginal tract, though data on colonization in the elderly are scarce. It is unknown whether the prevalence of GBS colonization is increasing in parallel to the observed rise of invasive infection. We conducted a three-year (2017-2019) prospective observational cross-sectional study in two teaching hospitals in Switzerland to determine the rate of GBS vaginal colonization in women over 60 years and i) to compare the proportions of known risk factors associated with invasive GBS diseases in colonized versus non-colonized women and ii) to evaluate the presence of GBS clusters with specific phenotypic and genotypic patterns in this population.

Methods: GBS screening was performed by using vaginal swabs collected during routine examination from women willing to participate in the study and to complete a questionnaire for risk factors. Isolates were characterized for antibiotic resistance profile, serotype and sequence type (ST).

Results: The GBS positivity rate in the elderly was 17% (44/255 positive samples), and similar to the one previously reported in pregnant women (around 20%). We could not find any association between participants' characteristics, previously published risk factors and GBS colonization. All strains were susceptible to penicillin, 22% (8/36) were not susceptible to erythromycin, 14% (5/36) were not susceptible to clindamycin and 8% (3/36) showed inducible clindamycin resistance. Both M and L phenotypes were each detected in one isolate. The most prevalent serotypes were III (33%, 12/36) and V (31%, 11/36). ST1 and ST19 accounted for 11% of isolates each (4/36); ST175 for 8% (3/36); and ST23, ST249 and ST297 for 6% each (2/36). Significantly higher rates of resistance to macrolides and clindamycin were associated with the ST1 genetic background of ST1.

Conclusions: Our findings indicate a similar colonization rate for pregnant and elderly women.

Trial Registration: Current Controlled Trial ISRCTN15468519 ; 06/01/2017.
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http://dx.doi.org/10.1186/s12879-021-06102-xDOI Listing
May 2021

Microbial Photoinactivation by Visible Light Results in Limited Loss of Membrane Integrity.

Antibiotics (Basel) 2021 Mar 23;10(3). Epub 2021 Mar 23.

Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, 89081 Ulm, Germany.

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 and 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 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.
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http://dx.doi.org/10.3390/antibiotics10030341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8005082PMC
March 2021

Photoinactivation of Staphylococci with 405 nm Light in a Trachea Model with Saliva Substitute at 37 °C.

Healthcare (Basel) 2021 Mar 11;9(3). Epub 2021 Mar 11.

Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, 89081 Ulm, Germany.

The globally observed rise in bacterial resistance against antibiotics has increased the need for alternatives to antibiotic treatments. The most prominent and important pathogen bacteria are the ESKAPE pathogens, which include among others , and . These species cause ventilator-associated pneumonia (VAP), which accounts for 24% of all nosocomial infections. In this study we tested the efficacy of photoinactivation with 405 nm violet light under conditions comparable to an intubated patient with artificial saliva for bacterial suspension at 37 °C. A technical trachea model was developed to investigate the visible light photoinactivation of as a non-pathogen surrogate of the ESKAPE pathogen (MRSA). The violet light was coupled into the tube with a fiber optic setup. The performed tests proved, that photoinactivation at 37 °C is more effective with a reduction of almost 3 log levels (99.8%) compared to 25 °C with a reduction of 1.2 log levels. The substitution of phosphate buffered saline (PBS) by artificial saliva solution slightly increased the efficiency during the experimental course. The increased efficiency might be caused by a less favorable environment for bacteria due to for example the ionic composition.
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http://dx.doi.org/10.3390/healthcare9030310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7998829PMC
March 2021

Unbiased Identification of Angiogenin as an Endogenous Antimicrobial Protein With Activity Against Virulent .

Front Microbiol 2020 18;11:618278. Epub 2021 Jan 18.

Institute of Medical Microbiology and Hygiene, University Hospital Ulm, Ulm, Germany.

Tuberculosis is a highly prevalent infectious disease with more than 1.5 million fatalities each year. Antibiotic treatment is available, but intolerable side effects and an increasing rate of drug-resistant strains of () may hamper successful outcomes. Antimicrobial peptides (AMPs) offer an alternative strategy for treatment of infectious diseases in which conventional antibiotic treatment fails. Human serum is a rich resource for endogenous AMPs. Therefore, we screened a library generated from hemofiltrate for activity against . Taking this unbiased approach, we identified Angiogenin as the single compound in an active fraction. The antimicrobial activity of endogenous Angiogenin against extracellular could be reproduced by synthetic Angiogenin. Using computational analysis, we identified the hypothetical active site and optimized the lytic activity by amino acid exchanges. The resulting peptide-Angie1-limited the growth of extra- and intracellular and the fast-growing pathogens , , and . Toward our long-term goal of evaluating Angie1 for therapeutic efficacy , we demonstrate that the peptide can be efficiently delivered into human macrophages liposomes and is not toxic for zebrafish embryos. Taken together, we define Angiogenin as a novel endogenous AMP and derive the small, bioactive fragment Angie1, which is ready to be tested for therapeutic activity in animal models of tuberculosis and infections with fast-growing bacterial pathogens.
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http://dx.doi.org/10.3389/fmicb.2020.618278DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7848861PMC
January 2021

Inactivation Effect of Violet and Blue Light on ESKAPE Pathogens and Closely Related Non-pathogenic Bacterial Species - A Promising Tool Against Antibiotic-Sensitive and Antibiotic-Resistant Microorganisms.

Front Microbiol 2020 13;11:612367. Epub 2021 Jan 13.

Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany.

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 , and 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.
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http://dx.doi.org/10.3389/fmicb.2020.612367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7838345PMC
January 2021

Deciphering Streptococcal Biofilms.

Microorganisms 2020 Nov 21;8(11). Epub 2020 Nov 21.

Institute of Medical Microbiology and Hygiene, University Hospital Ulm, 89073 Ulm, Germany.

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.
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http://dx.doi.org/10.3390/microorganisms8111835DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7700319PMC
November 2020

New Antibacterial Peptides from the Freshwater Mollusk (Pilsbry, 1927).

Biomolecules 2020 10 23;10(11). Epub 2020 Oct 23.

Center for Protein Studies, Faculty of Biology, University of Havana, 25 street, 10400 Havana, Cuba.

Antimicrobial peptides (AMPs) are biomolecules with antimicrobial activity against a broad group of pathogens. In the past few decades, AMPs have represented an important alternative for the treatment of infectious diseases. Their isolation from natural sources has been widely investigated. In this sense, mollusks are promising organisms for the identification of AMPs given that their immune system mainly relies on innate response. In this report, we characterized the peptide fraction of the Cuban freshwater snail (Pilsbry, 1927) and identified 37 different peptides by nanoLC-ESI-MS-MS technology. From these peptide sequences, using bioinformatic prediction tools, we discovered two potential antimicrobial peptides named Pom-1 (KCAGSIAWAIGSGLFGGAKLIKIKKYIAELGGLQ) and Pom-2 (KEIERAGQRIRDAIISAAPAVETLAQAQKIIKGG). Database search revealed that Pom-1 is a fragment of Closticin 574 previously isolated from the bacteria and Pom-2 is a fragment of cecropin D-like peptide first isolated from hemolymph. These sequences were chemically synthesized and evaluated against different human pathogens. Interestingly, structural predictions of both peptides in the presence of micelles showed models that comprise two alpha helices joined by a short loop. The CD spectra analysis of Pom-1 and Pom-2 in water showed for both structures a high random coil content, a certain content of α-helix and a low β-sheet content. Like other described AMPs displaying a disordered structure in water, the peptides may adopt a helical conformation in presence of bacterial membranes. In antimicrobial assays, Pom-1 demonstrated high activity against the Gram-negative bacteria and moderate activity against and . Neither of the two peptides showed antifungal action. Pom-1 moderately inhibits Zika Virus infection but slightly enhances HIV-1 infectivion in vitro. The evaluation of cell toxicity on primary human macrophages did not show toxicity on THP-1 cells, although slight overall toxicity was observed in high concentrations of Pom-1. We assume that both peptides may play a key role in innate defense of and represent promising antimicrobial candidates for humans.
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http://dx.doi.org/10.3390/biom10111473DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7690686PMC
October 2020

Respiratory ß-2-Microglobulin exerts pH dependent antimicrobial activity.

Virulence 2020 12;11(1):1402-1414

Institute of Medical Microbiology and Hygiene, University Hospital , Ulm, Germany.

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 and and to facilitate phagocytosis of . Using commercially available B2M we confirmed a dose-dependent inhibition of and . 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 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.
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http://dx.doi.org/10.1080/21505594.2020.1831367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7588194PMC
December 2020

Photoinactivation results of Enterococcus moraviensis with blue and violet light suggest the involvement of an unconsidered photosensitizer.

Biochem Biophys Res Commun 2020 12 29;533(4):813-817. Epub 2020 Sep 29.

Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, 89081, Germany.

Microorganisms can be photoinactivated with 405 and 450 nm irradiation, due to endogenous photosensitizers, which absorb light of these wavelengths and generate reactive oxygen species that destroy the cells from within. The photosensitizers assumed to be responsible are porphyrins in the spectral region around 405 nm and flavins at about 450 nm. The aim of this study was to investigate this hypothesis on enterococci, considering that they do not contain porphyrins. In photoinactivation experiments with Enterococcus moraviensis, 405 nm and 450 nm irradiation both led to a reduction of the bacterial concentration by several orders of magnitude with 405 nm irradiation being much more efficient. The measurement and analysis of the fluorescence spectra revealed no signs of porphyrins whereas flavins seemed to be rapidly converted to lumichrome by 405 nm radiation. Therefore, probably none of the usual suspects, porphyrins and flavins, was responsible for the photoinactivation of Enterococcus moraviensis during 405 nm irradiation. Fluorescence experiments revealed the spectra of lumichrome and NADH, which are both known photosensitizers. Presumably, one of them or both were actually involved here. As NADH and flavins (and therefore their photodegradation product lumichrome) are abundant in all microorganisms, they are probably also involved in 405 nm photoinactivation processes of other species.
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http://dx.doi.org/10.1016/j.bbrc.2020.09.091DOI Listing
December 2020

Enhancement of Contact Lens Disinfection by Combining Disinfectant with Visible Light Irradiation.

Int J Environ Res Public Health 2020 09 3;17(17). Epub 2020 Sep 3.

Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, 89081 Ulm, Germany.

Multiple use contact lenses have to be disinfected overnight to reduce the risk of infections. However, several studies demonstrated that not only microorganisms are affected by the disinfectants, but also ocular epithelial cells, which come into contact via residuals at reinsertion of the lens. Visible light has been demonstrated to achieve an inactivation effect on several bacterial and fungal species. Combinations with other disinfection methods often showed better results compared to separately applied methods. We therefore investigated contact lens disinfection solutions combined with 405 nm irradiation, with the intention to reduce the disinfectant concentration of ReNu Multiplus, OptiFree Express or AOSept while maintaining adequate disinfection results due to combination benefits. Pseudomonads, staphylococci and were studied with disk diffusion assay, colony forming unit (cfu) determination and growth delay. A log reduction of 4.49 was achieved for in 2 h for 40% ReNu Multiplus combined with an irradiation intensity of 20 mW/cm at 405 nm. For AOSept the combination effect was so strong that 5% of AOSept in combination with light exhibited the same result as 100% AOSept alone. Combination of disinfectants with visible violet light is therefore considered a promising approach, as a reduction of potentially toxic ingredients can be achieved.
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http://dx.doi.org/10.3390/ijerph17176422DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7504152PMC
September 2020

A Placenta Derived C-Terminal Fragment of β-Hemoglobin With Combined Antibacterial and Antiviral Activity.

Front Microbiol 2020 6;11:508. Epub 2020 Apr 6.

Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany.

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 IC 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 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.
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http://dx.doi.org/10.3389/fmicb.2020.00508DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7153485PMC
April 2020

Heterogeneity of Streptococcus anginosus ß-hemolysis in relation to CRISPR/Cas.

Mol Oral Microbiol 2020 04 6;35(2):56-65. Epub 2020 Feb 6.

Institute of Medical Microbiology and Hospital Hygiene, University of Ulm, Ulm, Germany.

Streptococcus anginosus is a commensal of the oral mucosa that can cause severe invasive infections. A considerable proportion of Streptococcus anginosus strains are ß-hemolytic due to the presence of an SLS-like gene cluster. However, the majority of strains do not display ß-hemolysis. To investigate ß-hemolysin heterogeneity in S. anginosus, we determined the presence of sag genes and correlated it with the presence of CRISPR/Cas genes in a collection of ß-hemolytic and non-ß-hemolytic strains. All of the ß-hemolytic strains carried the sag gene cluster. In contrast to other streptococci, clinical S. anginosus strains that do not display ß-hemolysis do not harbor sag genes. Phylogenetic analysis of the ß-hemolytic strains revealed that they belong to two previously defined clusters within S. anginosus. Correlation with CRISPR/Cas genes showed a significant difference for the presence of CRISPR/Cas in ß-hemolytic versus non-ß-hemolytic isolates. The presence of the CRISPR/Cas type IIA or type IIC locus is associated with the absence of sag genes; in 65% of the non-ß-hemolytic strains a CRISPR/Cas locus was found, while only 24% of ß-hemolytic strains carry CRISPR/Cas genes. Further analysis of the spacer content of the CRISPR systems revealed the presence of multiple self-targeting sequences directed against S. anginosus genes. These results support the hypothesis that horizontal gene transfer is involved in the acquisition of ß-hemolysin genes and that CRISPR/Cas may limit DNA uptake in S. anginosus.
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http://dx.doi.org/10.1111/omi.12278DOI Listing
April 2020

Design of a Helical-Stabilized, Cyclic, and Nontoxic Analogue of the Peptide Cm-p5 with Improved Antifungal Activity.

ACS Omega 2019 Nov 5;4(21):19081-19095. Epub 2019 Nov 5.

Center for Protein Studies, Faculty of Biology, University of Havana, 25 and I, 10400 La Habana, Cuba.

Following the information obtained by a rational design study, a cyclic and helical-stabilized analogue of the peptide Cm-p5 was synthetized. The cyclic monomer showed an increased activity in vitro against and , compared to Cm-p5. Initially, 14 mutants of Cm-p5 were synthesized following a rational design to improve the antifungal activity and pharmacological properties. Antimicrobial testing showed that the activity was lost in each of these 14 analogues, suggesting, as a main conclusion, that a Glu-His salt bridge could stabilize Cm-p5 helical conformation during the interaction with the plasma membrane. A derivative, obtained by substitution of Glu and His for Cys, was synthesized and oxidized with the generation of a cyclic monomer with improved antifungal activity. In addition, two dimers were generated during the oxidation procedure, a parallel and antiparallel one. The dimers showed a helical secondary structure in water, whereas the cyclic monomer only showed this conformation in SDS. Molecular dynamic simulations confirmed the helical stabilizations for all of them, therefore indicating the possible essential role of the Glu-His salt bridge. In addition, the antiparallel dimer showed a moderate activity against and a significant activity against . Neither the cyclic monomer nor the dimers were toxic against macrophages or THP-1 human cells. Due to its increased capacity for fungal control compared to fluconazole, its low cytotoxicity, together with a stabilized α-helix and disulfide bridges, that may advance its metabolic stability, and in vivo activity, the new cyclic Cm-p5 monomer represents a potential systemic antifungal therapeutic candidate.
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http://dx.doi.org/10.1021/acsomega.9b02201DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6868880PMC
November 2019

Photoinactivation Sensitivity of Staphylococcus carnosus to Visible-light Irradiation as a Function of Wavelength.

Photochem Photobiol 2020 01 22;96(1):156-169. Epub 2019 Oct 22.

Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany.

Inactivation properties of visible light are of increasing interest due to multiple possible fields of application concerning antibacterial treatment. For violet wavelengths, the generation of reactive oxygen species by porphyrins is accepted as underlying mechanism. However, there is still little knowledge about photosensitizers at blue wavelengths. While flavins were named as possible candidates, there is still no experimental evidence. This study investigates the photoinactivation sensitivity of Staphylococcus carnosus to selected wavelengths between 390 and 500 nm in 10- to 25-nm intervals. Absorption and fluorescence measurements in bacterial lysates confirmed inactivation findings. By means of a mathematical calculation in MATLAB , a fit of different photosensitizer absorption spectra to the measured action spectrum was determined to gain knowledge about the extent to which specific photosensitizers are involved. The most effective wavelength for S. carnosus at 415 nm could be explained by the involvement of zinc protoporphyrin IX. Between 450 and 470 nm, inactivation results indicated a broad plateau, statistically distinguishable from 440 and 480 nm. This observation points to flavins as responsible photosensitizers, which furthermore seem to be involved at violet wavelengths. A spectral scan of sensitivities might generally be an advantageous approach for examining irradiation impact.
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http://dx.doi.org/10.1111/php.13168DOI Listing
January 2020

[Invasive Eyelid Infections by β-Hemolytic Streptococci of Serogroup A].

Klin Monbl Augenheilkd 2020 Feb 11;237(2):180-184. Epub 2019 Sep 11.

Klinik für Augenheilkunde, Universitätsklinikum Ulm.

Background: Invasive soft tissue infections by are rapidly progressive and potentially life-threatening infectious diseases. These can also affect the eyelid. Aggressive virulence factors and the synthesis of exotoxins can lead to complications, such as periorbital necrotizing fasciitis (PONF) and streptococcal toxic shock syndrome (STSS). The clinical picture is characterized by four patients with invasive eyelid infections.

Materials And Methods: Photographic documentation, radiological imaging, laboratory and smear diagnostics and intravenous antibiotic therapy were performed on all patients according to the recommendations of the German Robert Koch Institute and the local infectiology board.

Results: In all patients, was culturally detected in a direct swab. The antibiogram showed sensitivity to the common intravenous antibiotics. The time interval between symptom onset and presentation at the clinic was between two days and one week. All patients had high systemic inflammatory parameters on admission: Pat. 1: CRP 259 mg/l, leukocytes 20.1 giga/l; Pat. 2: CRP 375 mg/l, leukocytes 15.6 giga/l; Pat. 3: CRP 378 mg/l, leukocytes 38.7 giga/l; Pat. 4: CRP 483 mg/l, leukocytes 1.7 giga/l; normal values: CRP < 5 mg/l, leucocytes 4.4 - 11.3 giga/l. In Pat. 2 and 3, a periorbital necrotizing fasciitis was diagnosed due to rapidly progressing necrosis in the area of cutis and subcutis and systemic toxicity. Pat. 3 and 4 met the diagnostic criteria of STSS. Pat. 2, 3 and 4 had to be relocated to an intermediate or intensive care unit with sepsis, despite immediate intravenous antibiotic therapy. Patient 3 underwent surgical debridement during the stay in the intensive care unit. Thanks to interdisciplinary management (ophthalmology, infectiology, ear, nose and throat medicine, internal medicine and intensive care medicine), all patients were finally discharged from our inpatient treatment in a significantly improved general condition.

Conclusion: Invasive streptococcal infections represent a challenge in the daily routine of an ophthalmologist. Interdisciplinary management and immediate onset of high-dose intravenous antibiotic therapy are crucial for successful treatment.
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http://dx.doi.org/10.1055/a-0972-9835DOI Listing
February 2020

Potential self-disinfection capacity of touch screen displays.

J Biophotonics 2019 10 15;12(10):e201900118. Epub 2019 Jul 15.

Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany.

Touch screen displays are potential pathogen reservoirs and involved in the spread of hospital acquired infections. They emit visible light that is known for a weak but proven antimicrobial photoinactivation effect, so the question is whether displays have the potential to disinfect themselves. To test the antimicrobial capacity of touch screen displays, Staphylococcus carnosus are distributed on Samsung tablets and illuminated for up to 36 hours. The average number of colony forming units decreases with time with white light being the most efficient followed by blue, green and red light. Increasing the illumination intensity by a mirror leads to a faster bacterial decrease up to a 90% reduction in 15 hours. A 99.99% reduction of staphylococci should be possible by turning on the display over the weekend.
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http://dx.doi.org/10.1002/jbio.201900118DOI Listing
October 2019

Capsular Type, Sequence Type and Microbial Resistance Factors Impact on DNase Activity of Strains from Human and Bovine Origin.

Eur J Microbiol Immunol (Bp) 2018 Dec 11;8(4):149-154. Epub 2018 Dec 11.

Department of Infectious Diseases, National Institute of Health, Lisbon.

Extracellular deoxyribonucleases (DNases) contribute to the spread of pathogenic bacteria through the evasion from host innate immunity. Our main objective was to evaluate the production of extracellular DNases by human and bovine clinical strains and perform a correlation of genetic lineages and DNase activity with capsular type, genetic determinants, clinical origin (colonization and infection), and host (human or bovine). DNase activity was evaluated by qualitative and quantitative assays for a collection of 406 human ( = 285) and bovine ( = 121) strains. All (121/121) bovine were isolated from mastitis and revealed to be DNase (+), indicating a putative pathogenic role in this clinical scenario. From the human strains, 86% (245/285) showed DNase activity, among which all strains belonging to capsular types, namely, Ia, Ib, III-2, and IV. All CC17 strains ( = 58) and 56/96 (58.3%) of the CC19 displayed DNase activity. DNase (-) strains belonged to the CC19 group. However, the subcharacterization of CC19 strains through multiple-locus variable number tandem repeat analysis (MLVA), antibiotic resistance, mobile elements, and surface proteins did not provide any distinction among DNase producers and non-producers. The production of DNases by all human CC17 strains, about two-fifths of human CC19, and all bovine strains, suggest an important contribution of DNases to hypervirulence.
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http://dx.doi.org/10.1556/1886.2018.00026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6348702PMC
December 2018

Regulation of the β-hemolysin gene cluster of Streptococcus anginosus by CcpA.

Sci Rep 2018 06 13;8(1):9028. Epub 2018 Jun 13.

Institute of Medical Microbiology and Hospital Hygiene, University of Ulm, Ulm, Germany.

Streptococcus anginosus is increasingly recognized as an opportunistic pathogen. However, our knowledge about virulence determinants in this species is scarce. One exception is the streptolysin-S (SLS) homologue responsible for the β-hemolytic phenotype of the S. anginosus type strain. In S. anginosus the expression of the hemolysin is reduced in the presence of high glucose concentrations. To investigate the genetic mechanism of the hemolysin repression we created an isogenic ccpA deletion strain. In contrast to the wild type strain, this mutant exhibits hemolytic activity in presence of up to 25 mM glucose supplementation, a phenotype that could be reverted by ccpA complementation. To further demonstrate that CcpA directly regulates the hemolysin expression, we performed an in silico analysis of the promoter of the SLS gene cluster and we verified the binding of CcpA to the promoter by electrophoretic mobility shift assays. This allowed us to define the CcpA binding site in the SLS promoter region of S. anginosus. In conclusion, we report for the first time the characterization of a potential virulence regulator in S. anginosus.
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http://dx.doi.org/10.1038/s41598-018-27334-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5998137PMC
June 2018

Group B Streptococcal Colonization, Molecular Characteristics, and Epidemiology.

Front Microbiol 2018 14;9:437. Epub 2018 Mar 14.

Institute of Medical Microbiology and Hygiene, University of Ulm, Ulm, Germany.

or group B streptococcus (GBS) is a leading cause of serious neonatal infections. GBS is an opportunistic commensal constituting a part of the intestinal and vaginal physiologic flora and maternal colonization is the principal route of GBS transmission. GBS is a pathobiont that converts from the asymptomatic mucosal carriage state to a major bacterial pathogen causing severe invasive infections. At present, as many as 10 serotypes (Ia, Ib, and II-IX) are recognized. The aim of the current review is to shed new light on the latest epidemiological data and clonal distribution of GBS in addition to discussing the most important colonization determinants at a molecular level. The distribution and predominance of certain serotypes is susceptible to variations and can change over time. With the availability of multilocus sequence typing scheme (MLST) data, it became clear that GBS strains of certain clonal complexes possess a higher potential to cause invasive disease, while other harbor mainly colonizing strains. Colonization and persistence in different host niches is dependent on the adherence capacity of GBS to host cells and tissues. Bacterial biofilms represent well-known virulence factors with a vital role in persistence and chronic infections. In addition, GBS colonization, persistence, translocation, and invasion of host barriers are largely dependent on their adherence abilities to host cells and extracellular matrix proteins (ECM). Major adhesins mediating GBS interaction with host cells include the fibrinogen-binding proteins (Fbs), the laminin-binding protein (Lmb), the group B streptococcal C5a peptidase (ScpB), the streptococcal fibronectin binding protein A (SfbA), the GBS immunogenic bacterial adhesin (BibA), and the hypervirulent adhesin (HvgA). These adhesins facilitate persistent and intimate contacts between the bacterial cell and the host, while global virulence regulators play a major role in the transition to invasive infections. This review combines for first time epidemiological data with data on adherence and colonization for GBS. Investigating the epidemiology along with understanding the determinants of mucosal colonization and the development of invasive disease at a molecular level is therefore important for the development of strategies to prevent invasive GBS disease worldwide.
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http://dx.doi.org/10.3389/fmicb.2018.00437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5861770PMC
March 2018

Molecular dynamics simulation of metal free structure of Lmb, a laminin-binding adhesin of Streptococcus agalactiae: metal removal and its structural implications.

J Biomol Struct Dyn 2019 Feb 23;37(3):714-725. Epub 2018 Feb 23.

a Centre of Advanced Study in Crystallography and Biophysics , University of Madras, Guindy Campus , Chennai , India.

Metal-binding receptors are one of the extracellular components of ATP-binding cassette transporters that are essential for regulation of metal homeostasis in bacteria. Laminin-binding adhesin (Lmb) of Streptococcus agalactiae falls under this class of solute binding proteins. It binds to zinc with a high affinity. Crystal structure of Lmb solved previously by our group reveals that the zinc is tetrahedrally coordinated by three histidines and a glutamate at the interdomain cleft. Lmb contains a long disordered loop close to the metal-binding site whose precise function is unknown. Several experimental attempts to produce apo-Lmb failed and this prompted us to carry out in silico studies to analyse the structural importance of the metal in Lmb. Here, we present the results of the molecular dynamics (MD) simulation studies of native, apo-(metal removed) and the long loop truncated Lmb models along with a homologous protein, TroA from Treponema pallidum that was taken up for validating the MD results of Lmb. Absence of a metal results in significant structural changes in Lmb, particularly at the metal-binding pocket and with the long loop, although the overall fold is retained. This study thus revealed that the Lmb can exist in different conformational states with subtle differences in the overall fold based on the presence or absence of the metal. This could be functionally important for a putative metal uptake and release and also for the adhesive function of Lmb in recognizing laminin, which contains a high number of zinc finger motifs.
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http://dx.doi.org/10.1080/07391102.2018.1438923DOI Listing
February 2019

Acid Stress Response Mechanisms of Group B Streptococci.

Front Cell Infect Microbiol 2017 7;7:395. Epub 2017 Sep 7.

Institute of Medical Microbiology and Hygiene, University of UlmUlm, Germany.

Group B streptococcus (GBS) is a leading cause of neonatal mortality and morbidity in the United States and Europe. It is part of the vaginal microbiota in up to 30% of pregnant women and can be passed on to the newborn through perinatal transmission. GBS has the ability to survive in multiple different host niches. The pathophysiology of this bacterium reveals an outstanding ability to withstand varying pH fluctuations of the surrounding environments inside the human host. GBS host pathogen interations include colonization of the acidic vaginal mucosa, invasion of the neutral human blood or amniotic fluid, breaching of the blood brain barrier as well as survival within the acidic phagolysosomal compartment of macrophages. However, investigations on GBS responses to acid stress are limited. Technologies, such as whole genome sequencing, genome-wide transcription and proteome mapping facilitate large scale identification of genes and proteins. Mechanisms enabling GBS to cope with acid stress have mainly been studied through these techniques and are summarized in the current review.
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http://dx.doi.org/10.3389/fcimb.2017.00395DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5594096PMC
May 2018

Reliable Detection of Group B Streptococcus in the Clinical Laboratory.

J Clin Microbiol 2017 09 28;55(9):2590-2598. Epub 2017 Jun 28.

Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Ulm, Ulm, Germany.

Group B streptococcus (GBS) is a leading cause of invasive neonatal infections and a significant pathogen in immunocompromised adults. Screening to detect GBS colonization in pregnant women determines the need for antibiotic prophylaxis in that pregnancy. Efficient determination of the GBS colonization status of pregnant women is crucial. Methods that maximize the probability of GBS recovery are needed. The availability of technologies such as matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), molecular techniques, and chromogenic culture media, including Granada-type media, have changed the scenario for GBS detection and identification. This review presents and evaluates novel diagnostic tools, as well as classic identification techniques, for GBS species determination.
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http://dx.doi.org/10.1128/JCM.00582-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648696PMC
September 2017

Clinical strains of Streptococcus agalactiae carry two different variants of pathogenicity island XII.

Folia Microbiol (Praha) 2017 Sep 18;62(5):393-399. Epub 2017 Mar 18.

Institute of Experimental Medicine, Pavlova Street, 12, 197376, Saint-Petersburg, Russia.

Streptococcus agalactiae or Group B streptococci (GBS) are a common cause of serious diseases of newborns and adults. GBS pathogenicity largely depends on genes located on the accessory genome including several pathogenicity islands (PAI). The present paper is focused on the structure and molecular epidemiological analysis of one of the GBS pathogenicity islands-the pathogenicity island PAI XII (Glaser et al. Mol Microbiol 45(6):1499-1513, 2002). This PAI was found to be composed of three different mobile genetic elements: a composite transposon (PAI-C), a genomic islet (PAI-B), and a pathogenicity island associated with gene sspB1 (PAI-A). PAI-A in GBS has a homolog--PAI-A1 with similar, but a different genetic constellation. PCR-based analysis of GBS collections from different countries revealed that a strains lineage with PAI-A is less common than PAI-A1 and was determined to be present only among the strains obtained from Russia. Our results suggest that PAI-A and PAI-A1 have the same progenitor, which evolved independently and appeared in the GBS genome as separate genetic events. Results of this study reflect specific geographical distribution of the GBS strains with the mobile genetic element under study.
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http://dx.doi.org/10.1007/s12223-017-0509-8DOI Listing
September 2017

Group B Streptococcal Toxic Shock Syndrome and covR/S Mutations Revisited.

Emerg Infect Dis 2017 01;23(1):150-152

Gene mutations in the virulence regulator CovR/S of group A Streptococcus play a substantial role in the pathogenesis of streptococcal toxic shock syndrome. We screened 25 group B Streptococcus (GBS) isolates obtained from patients with streptococcal toxic shock syndrome and found only 1 GBS clone harboring this kind of mutation.
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http://dx.doi.org/10.3201/eid2301.161063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5176209PMC
January 2017

Making Fluorescent Streptococci and Enterococci for Live Imaging.

Methods Mol Biol 2017 ;1535:141-159

Institute of Medical Microbiology and Hygiene, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany.

Since the discovery of the green fluorescent protein (GFP) from the jellyfish Aequorea victoria, outstanding fluorescent labeling tools with numerous applications in vastly different areas of life sciences have been developed. To optimize GFP for diverse life science applications, a large variety of GFP derivatives with different environmental characteristics have been generated by mutagenesis. The enhanced green fluorescent protein (EGFP) is a well-known GFP derivative with highly increased fluorescence intensity compared to the GFP wild-type molecule. Further optimization strategies include numerous GFP derivatives with blue- and yellow-shifted fluorescence and increased pH-stability. The methods reported herein describe in detail the construction of customized fluorescent GFP reporter plasmids where the fluorescence gene is expressed under the control of a certain bacterial promoter of interest. Special attention is given to the GFP derivatives EGFP and Sirius. We explain how to generate EGFP/Sirius expressing streptococci and how to employ recombinantly labeled streptococci in different downstream fluorescent applications.
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http://dx.doi.org/10.1007/978-1-4939-6673-8_9DOI Listing
January 2018

A streptococcal NRAMP homologue is crucial for the survival of Streptococcus agalactiae under low pH conditions.

Mol Microbiol 2016 05 29;100(4):589-606. Epub 2016 Feb 29.

Institute of Medical Microbiology and Hygiene, University of Ulm, Ulm, Germany.

Streptococcus agalactiae or Group B Streptococcus (GBS) is a commensal bacterium of the human gastrointestinal and urogenital tracts as well as a leading cause of neonatal sepsis, pneumonia and meningitis. Maternal vaginal carriage is the main source for GBS transmission and thus the most important risk factor for neonatal disease. Several studies in eukaryotes identified a group of proteins natural resistance-associated macrophage protein (NRAMP) that function as divalent cation transporters for Fe(2+) and Mn(2+) and confer on macrophages the ability to control replication of bacterial pathogens. Genome sequencing predicted potential NRAMP homologues in several prokaryotes. Here we describe for the first time, a pH-regulated NRAMP Mn(2+) /Fe(2+) transporter in GBS, designated MntH, which confers resistance to reactive oxygen species (ROS) and is crucial for bacterial growth and survival under low pH conditions. Our investigation implicates MntH as an important colonization determinant for GBS in the maternal vagina as it helps bacteria to adapt to the harsh acidic environment, facilitates bacterial adherence, contributes to the coexistence with the vaginal microbiota and plays a role in GBS intracellular survival inside macrophages.
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http://dx.doi.org/10.1111/mmi.13335DOI Listing
May 2016

Chromosomally and Extrachromosomally Mediated High-Level Gentamicin Resistance in Streptococcus agalactiae.

Antimicrob Agents Chemother 2016 Jan 4;60(3):1702-7. Epub 2016 Jan 4.

Institute of Medical Microbiology and Hygiene, University of Ulm, Ulm, Germany

Streptococcus agalactiae (group B Streptococcus [GBS]) is a leading cause of sepsis in neonates. The rate of invasive GBS disease in nonpregnant adults also continues to climb. Aminoglycosides alone have little or no effect on GBS, but synergistic killing with penicillin has been shown in vitro. High-level gentamicin resistance (HLGR) in GBS isolates, however, leads to the loss of a synergistic effect. We therefore performed a multicenter study to determine the frequency of HLGR GBS isolates and to elucidate the molecular mechanisms leading to gentamicin resistance. From eight centers in four countries, 1,128 invasive and colonizing GBS isolates were pooled and investigated for the presence of HLGR. We identified two strains that displayed HLGR (BSU1203 and BSU452), both of which carried the aacA-aphD gene, typically conferring HLGR. However, only one strain (BSU1203) also carried the previously described chromosomal gentamicin resistance transposon designated Tn3706. For the other strain (BSU452), plasmid purification and subsequent DNA sequencing resulted in the detection of plasmid pIP501 carrying a remnant of a Tn3 family transposon. Its ability to confer HLGR was proven by transfer into an Enterococcus faecalis isolate. Conversely, loss of HLGR was documented after curing both GBS BSU452 and the transformed E. faecalis strain from the plasmid. This is the first report showing plasmid-mediated HLGR in GBS. Thus, in our clinical GBS isolates, HLGR is mediated both chromosomally and extrachromosomally.
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http://dx.doi.org/10.1128/AAC.01933-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4775929PMC
January 2016