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Berlin Brandenburg

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  • 1
    Language: English
    In: The Journal of infectious diseases, 01 December 2016, Vol.214(11), pp.1615-1617
    Keywords: Cervicovaginal ; Gonorrhea ; Microbiome ; Sialidases ; Transmission ; Gonorrhea ; Neisseria Gonorrhoeae -- Immunology
    ISSN: 00221899
    E-ISSN: 1537-6613
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  • 2
    In: Annals of the New York Academy of Sciences, August 2011, Vol.12301(1), pp.E19-E28
    Description: The strict human pathogen has caused gonorrhea for thousands of years, and currently gonorrhea is the second most prevalent bacterial sexually transmitted infection worldwide. Given the ancient nature of and its unique obligate relationship with humankind over the millennia, its remarkable ability to adapt to the host immune system and cause repeated infections, and its propensity to develop resistance to all clinically useful antibiotics, the gonococcus is an ideal pathogen on which to study the evolution of bacterial pathogenesis, including antimicrobial resistance, over the long term and within the host during infection. Recently, the first gonococcus displaying high‐level resistance to ceftriaxone, identified in Japan, was characterized in detail. Ceftriaxone is the last remaining option for empirical first‐line treatment, and now seems to be evolving into a true “superbug.” In the near future, gonorrhea may become untreatable in certain circumstances. Herein, the history of antibiotics used for treatment of gonorrhea, the evolution of resistance emergence in , the linkage between resistance and biological fitness of , lessons learned, and future perspectives are reviewed and discussed.
    Keywords: Neisseria Gonorrhoeae ; Gonorrhea ; Antimicrobial Resistance ; Genetics ; Evolution
    ISSN: 0077-8923
    E-ISSN: 1749-6632
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  • 3
    Language: English
    In: PLoS ONE, 01 January 2013, Vol.8(2), p.e56097
    Description: The surface-exposed NadA adhesin produced by a subset of capsular serogroup B strains of Neisseria meningitidis is currently being considered as a vaccine candidate to prevent invasive disease caused by a hypervirulent lineage of meningococci. Levels of NadA are known to be controlled by both transcriptional regulatory factors and a component of human saliva, 4-hydroxyphenylacetic acid. Herein, we confirmed the capacity of a DNA-binding protein termed FarR to negatively control nadA expression. We also found that a known transcriptional regulator of farR in N. gonorrhoeae termed MtrR can have a negative regulatory impact on farR and nadA expression, especially when over-expressed. MtrR-mediated repression of nadA was found to be direct, and its binding to a target DNA sequence containing the nadA promoter influenced formation and/or stability of FarR::nadA complexes. The complexity of the multi-layered regulation of nadA uncovered during this investigation suggests that N. meningitidis modulates NadA adhesin protein levels for the purpose of interacting with host cells yet avoiding antibody directed against surface exposed epitopes.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 4
    Language: English
    In: 2014, Vol.9(1), p.e87688
    Description: Neisseria gonorrhoeae is a strict human pathogen that causes the sexually transmitted infection termed gonorrhea. The gonococcus can survive extracellularly and intracellularly, but in both environments the bacteria must acquire iron from host proteins for survival. However, upon infection the host uses a defensive response by limiting the bioavailability of iron by a number of mechanisms including the enhanced expression of hepcidin, the master iron-regulating hormone, which reduces iron uptake from the gut and retains iron in macrophages. The host also secretes the antibacterial protein NGAL, which sequesters bacterial siderophores and therefore inhibits bacterial growth. To learn whether intracellular gonococci can subvert this defensive response, we examined expression of host genes that encode proteins involved in modulating levels of intracellular iron. We found that N. gonorrhoeae can survive in association (tightly adherent and intracellular) with monocytes and macrophages and upregulates a panel of its iron-responsive genes in this environment. We also found that gonococcal infection of human monocytes or murine macrophages resulted in the upregulation of hepcidin, NGAL, and NRAMP1 as well as downregulation of the expression of the gene encoding the short chain 3-hydroxybutyrate dehydrogenase (BDH2); BDH2 catalyzes the production of the mammalian siderophore 2,5-DHBA involved in chelating and detoxifying iron. Based on these findings, we propose that N. gonorrhoeae can subvert the iron-limiting innate immune defenses to facilitate iron acquisition and intracellular survival.
    Keywords: Research Article ; Biology ; Medicine
    E-ISSN: 1932-6203
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  • 5
    In: Infection and Immunity, 2010, Vol. 78(7), p.3187
    Description: Polyamines are biogenic polycationic molecules involved in key cellular functions. Extracellular polyamines found in bodily fluids or laboratory media can be imported by bacteria or bind to negatively charged bacterial surface structures, where they can impair binding of antimicrobials. We hypothesized that the presence of polyamines in fluids that bathe urogenital mucosal surfaces could alter the susceptibility of the sexually transmitted strict human pathogen Neisseria gonorrhoeae to mediators of the innate host defense. Herein we report that polyamines can significantly increase gonococcal resistance to two structurally diverse cationic antimicrobial peptides (polymyxin B and LL-37) but not to antibiotics that exert activity in the cytosol or periplasm (e.g., ciprofloxacin, spectinomycin, or penicillin). The capacity of polyamines to increase gonococcal resistance to cationic antimicrobial peptides was dose dependent, correlated with the degree of cationicity, independent of a polyamine transport system involving the polyamine permeases PotH and PotI, and was reversible. In addition, we found that polyamines increase gonococcal resistance to complement-mediated killing by normal human serum. We propose that polyamines in genital mucosal fluids may enhance gonococcal survival during infection by reducing bacterial susceptibility to host-derived antimicrobials that function in innate host defense.
    Keywords: Antimicrobial Cationic Peptides -- Antagonists & Inhibitors ; Biogenic Polyamines -- Pharmacology ; Gonorrhea -- Immunology ; Immunity, Innate -- Drug Effects ; Neisseria Gonorrhoeae -- Drug Effects;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 6
    In: Antimicrobial Agents and Chemotherapy, 2010, Vol. 54(1), p.506
    Description: Neisseria meningitidis can produce a TolC-like protein needed for secretion of FrpC but not efflux of antimicrobials. We now report that expression of the meningococcal tolC gene in a TolC-deficient strain of Escherichia coli can restore properties of alpha-hemolysis and antimicrobial resistance known to involve efflux pumps.
    Keywords: Medicine ; Biology ; Pharmacy, Therapeutics, & Pharmacology;
    ISSN: 0066-4804
    ISSN: 00664804
    E-ISSN: 10986596
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  • 7
    Language: English
    In: PLOS ONE, 8/23/2018, Vol.13(8), p.e0202437
    Description: All Neisseria gonorrhoeae strains whose DNA sequences have been determined possess filamentous phage sequences representing their full genomes. The presence of filamentous phage DNA sequences in all sequenced N. gonorrhoeae strains suggest that purified phage particles might be used as a gonococcal vaccine. To test this hypothesis, we purified filamentous Ngo[PHI]fil phages and immunized rabbits subcutaneously. The elicited sera contained large quantities of anti-phage IgG and IgA antibodies that bound to the surface of N. gonorrhoeae cells, as shown by ELISA and flow cytometry. The elicited sera bound to the structural Ngo[PHI]6fil proteins present in phage particles and to N. gonorrhoeae cells. The sera did not react with gonococcal outer membrane proteins. The sera also had bactericidal activity and blocked adhesion of gonococci to tissue culture cells. These data demonstrate that Ngo[PHI]fil phage particles can induce antibodies with anti-gonococcal activity and may be a candidate for vaccine development.
    Keywords: Bacteriophages – Research ; Gene Expression – Research ; Neisseria Gonorrhoeae – Genetic Aspects ; Neisseria Gonorrhoeae – Research;
    ISSN: PLOS ONE
    E-ISSN: 1932-6203
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  • 8
    Language: English
    In: Antimicrobial agents and chemotherapy, June 2014, Vol.58(6), pp.3556-9
    Description: The contribution of drug efflux pumps in clinical isolates of Neisseria gonorrhoeae that express extensively drug-resistant or multidrug-resistant phenotypes has heretofore not been examined. Accordingly, we assessed the effect on antimicrobial resistance of loss of the three gonococcal efflux pumps associated with a known capacity to export antimicrobials (MtrC-MtrD-MtrE, MacA-MacB, and NorM) in such clinical isolates. We report that the MIC of several antimicrobials, including seven previously and currently recommended for treatment was significantly impacted.
    Keywords: Anti-Bacterial Agents -- Pharmacology ; Genes, Mdr -- Physiology ; Gonorrhea -- Microbiology ; Membrane Transport Proteins -- Genetics ; Neisseria Gonorrhoeae -- Genetics
    ISSN: 00664804
    E-ISSN: 1098-6596
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  • 9
    Language: English
    In: BBA - Biomembranes, October 2011, Vol.1808(10), pp.2544-2550
    Description: Signal sequence non-optimal codons have been shown to be important for the folding and efficient export of maltose binding protein (MBP), a SecB dependent protein. In this study, we analysed the importance of signal sequence non-optimal codons of TolB, a signal recognition particle (SRP) dependent exported protein. The protein production levels of wild type TolB (TolB-wt) and a mutant allele of TolB in which all signal sequence non-optimal codons were changed to a synonymous optimal codon (TolB-opt), revealed that TolB-opt production was 12-fold lower than TolB-wt. This difference could not be explained by changes in mRNA levels, or plasmid copy number, which was the same in both strains. A directed evolution genetic screen was used to select for mutants in the TolB-opt signal sequence that resulted in higher levels of TolB production. Analysis of the 46 independent TolB mutants that reverted to wild type levels of expression revealed that at least four signal sequence non-optimal codons were required. These results suggest that non-optimal codons may be required for the folding and efficient export of all proteins exported via the Sec system, regardless of whether they are dependent on SecB or SRP for delivery to the inner membrane. ► Signal sequence rare codons are required for export of SRP-dependent proteins. ► Selection experiment demonstrates that 〉 3 rare-codons required for efficient export. ► Study confirms that rare codons are required for both SRP and SecB dependent export.
    Keywords: Protein Export ; Codon Usage ; Evolution ; Signal Recognition Particle ; Chemistry
    ISSN: 0005-2736
    E-ISSN: 1879-2642
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  • 10
    Language: English
    In: BBA - Biomembranes, November 2015, Vol.1848(11), pp.3101-3111
    Description: Antimicrobial peptides (AMPs) are at the front-line of host defense during infection and play critical roles both in reducing the microbial load early during infection and in linking innate to adaptive immunity. However, successful pathogens have developed mechanisms to resist AMPs. Although considerable progress has been made in elucidating AMP-resistance mechanisms of pathogenic bacteria in vitro, less is known regarding the in vivo significance of such resistance. Nevertheless, progress has been made in this area, largely by using murine models and, in two instances, human models of infection. Herein, we review progress on the use of in vivo infection models in AMP research and discuss the AMP resistance mechanisms that have been established by in vivo studies to contribute to microbial infection. We posit that in vivo infection models are essential tools for investigators to understand the significance to pathogenesis of genetic changes that impact levels of bacterial susceptibility to AMPs. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.
    Keywords: Antimicrobial Peptides ; Cell Envelope Modifications ; In Vivo Models ; Pathogenesis ; Resistance Mechanisms ; Transporters ; Chemistry
    ISSN: 0005-2736
    E-ISSN: 1879-2642
    E-ISSN: 18782434
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