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  • 1
    Online Resource
    Online Resource
    Localization of Haemophilus ducreyi at the Pustular Stage of Disease in the Human Model of Infection
    American Society for Microbiology ; 2000
    In:  Infection and Immunity Vol. 68, No. 4 ( 2000-04), p. 2309-2314
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 68, No. 4 ( 2000-04), p. 2309-2314
    Abstract: To localize Haemophilus ducreyi in vivo, human subjects were experimentally infected with H. ducreyi until they developed a painful pustule or for 14 days. Lesions were biopsied, and biopsy samples were fixed in 4% paraformaldehyde, and cryosectioned. Sections were stained with polyclonal anti- H. ducreyi antiserum or H. ducreyi -specific monoclonal antibodies (MAbs) and fluorescently tagged secondary antibodies and examined by confocal microscopy. We identified H. ducreyi in 16 of 18 pustules but did not detect bacteria in the one papule examined. H. ducreyi was observed as individual cells and in clumps or chains. Staining with MAbs 2D8, 5C9, 3B9, 2C7, and 9D12 demonstrated that H. ducreyi expresses the major pilus subunit, FtpA, the 28-kDa outer membrane protein Hlp, the 18-kDa outer membrane protein PAL, and the major outer membrane protein (MOMP) or OmpA2 in vivo. By dual staining with polyclonal anti- H. ducreyi antiserum and MAbs that recognize human skin components, we observed bacteria within the neutrophilic infiltrates of all positively staining pustules and in the dermis of 10 of 16 pustules. We were unable to detect bacteria associated with keratinocytes in the samples examined. The data suggest that H. ducreyi is found primarily in association with neutrophils and in the dermis at the pustular stage of disease in the human model of infection.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.68.4.2309-2314.2000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2000
    detail.hit.zdb_id: 1483247-1
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  • 2
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    Online Resource
    Binding of Haemophilus ducreyi to Extracellular Matrix Proteins
    American Society for Microbiology ; 1999
    In:  Infection and Immunity Vol. 67, No. 5 ( 1999-05), p. 2649-2652
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 67, No. 5 ( 1999-05), p. 2649-2652
    Abstract: We developed an enzyme-linked immunosorbent assay-based assay to assess Haemophilus ducreyi binding to extracellular matrix (ECM) proteins. H. ducreyi 35000HP bound to fibronectin, laminin, and type I and III collagen but not to type IV, V, or VI collagen or elastin. Isogenic strains with mutations in ftpA or losB bound as well as the parent, suggesting that neither pili nor full-length lipooligosaccharide is required for H. ducreyi to bind to ECM proteins.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.67.5.2649-2652.1999
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
    detail.hit.zdb_id: 1483247-1
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  • 3
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    Online Resource
    Differences in Host Susceptibility to Disease Progression in the Human Challenge Model of Haemophilus ducreyi Infection
    American Society for Microbiology ; 2003
    In:  Infection and Immunity Vol. 71, No. 11 ( 2003-11), p. 6658-6663
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 71, No. 11 ( 2003-11), p. 6658-6663
    Abstract: With human volunteers inoculated at two sites with Haemophilus ducreyi , outcomes for a subject were not independent. In a reinfection trial, 2 of 11 previous pustule formers and 6 of 10 previous resolvers resolved all sites of infection. There was no correlation between serum bactericidal or phagocytic activity and outcome in the trial. These data indicate that different hosts are differentially susceptible to disease progression versus resolution in the model.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.71.11.6658-6663.2003
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2003
    detail.hit.zdb_id: 1483247-1
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  • 4
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    Online Resource
    Deletion of mtrC in Haemophilus ducreyi Increases Sensitivity to Human Antimicrobial Peptides and Activates the CpxRA Regulon
    American Society for Microbiology ; 2011
    In:  Infection and Immunity Vol. 79, No. 6 ( 2011-06), p. 2324-2334
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 79, No. 6 ( 2011-06), p. 2324-2334
    Abstract: Haemophilus ducreyi resists killing by antimicrobial peptides encountered during human infection, including cathelicidin LL-37, α-defensins, and β-defensins. In this study, we examined the role of the proton motive force-dependent multiple transferable resistance (MTR) transporter in antimicrobial peptide resistance in H. ducreyi . We found a proton motive force-dependent effect on H. ducreyi 's resistance to LL-37 and β-defensin HBD-3, but not α-defensin HNP-2. Deletion of the membrane fusion protein MtrC rendered H. ducreyi more sensitive to LL-37 and human β-defensins but had relatively little effect on α-defensin resistance. The mtrC mutant 35000HP mtrC exhibited phenotypic changes in outer membrane protein profiles, colony morphology, and serum sensitivity, which were restored to wild type by trans -complementation with mtrC . Similar phenotypes were reported in a cpxA mutant; activation of the two-component CpxRA regulator was confirmed by showing transcriptional effects on CpxRA-regulated genes in 35000HP mtrC . A cpxR mutant had wild-type levels of antimicrobial peptide resistance; a cpxA mutation had little effect on defensin resistance but led to increased sensitivity to LL-37. 35000HP mtrC was more sensitive than the cpxA mutant to LL-37, indicating that MTR contributed to LL-37 resistance independent of the CpxRA regulon. The CpxRA regulon did not affect proton motive force-dependent antimicrobial peptide resistance; however, 35000HP mtrC had lost proton motive force-dependent peptide resistance, suggesting that the MTR transporter promotes proton motive force-dependent resistance to LL-37 and human β-defensins. This is the first report of a β-defensin resistance mechanism in H. ducreyi and shows that LL-37 resistance in H. ducreyi is multifactorial.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.01316-10
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2011
    detail.hit.zdb_id: 1483247-1
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  • 5
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    Online Resource
    Haemophilus ducreyi Associates with Phagocytes, Collagen, and Fibrin and Remains Extracellular throughout Infection of Human Volunteers
    American Society for Microbiology ; 2001
    In:  Infection and Immunity Vol. 69, No. 4 ( 2001-04), p. 2549-2557
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 69, No. 4 ( 2001-04), p. 2549-2557
    Abstract: In a previous study, Haemophilus ducreyi was found in the pustule and dermis of samples obtained at the clinical end point in the human model of infection. To understand the kinetics of localization, we examined infected sites at 0, 24, and 48 h after inoculation and at the clinical end point. Immediately after inoculation, bacteria were found predominantly in the dermis but also in the epidermis. Few bacteria were detectable at 24 h; however, by 48 h, bacteria were readily seen in the pustule and dermis. H. ducreyi was associated with polymorphonuclear leukocytes and macrophages in the pustule and at its base, but was not associated with T cells, Langerhans' cells, or fibroblasts. H. ducreyi colocalized with collagen and fibrin but not laminin or fibronectin. Association with phagocytes, collagen, and fibrin was seen as early as 48 h and persisted at the pustular stage of disease. Optical sectioning by confocal microscopy and transmission electron microscopy both failed to demonstrate intracellular H. ducreyi . These data identify collagen and fibrin as potentially important targets of adherence in vivo and strongly suggest that H. ducreyi remains extracellular throughout infection and survives by resisting phagocytic killing in vivo.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.69.4.2549-2557.2001
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2001
    detail.hit.zdb_id: 1483247-1
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  • 6
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    Online Resource
    Haemophilus ducreyi SapA Contributes to Cathelicidin Resistance and Virulence in Humans
    American Society for Microbiology ; 2010
    In:  Infection and Immunity Vol. 78, No. 3 ( 2010-03), p. 1176-1184
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 78, No. 3 ( 2010-03), p. 1176-1184
    Abstract: Haemophilus ducreyi is an extracellular pathogen of human epithelial surfaces that resists human antimicrobial peptides (APs). The organism's genome contains homologs of genes s ensitive to a ntimicrobial p eptides ( sap operon) in nontypeable Haemophilus influenzae . In this study, we characterized the sap -containing loci of H. ducreyi 35000HP and demonstrated that sapA is expressed in broth cultures and H. ducreyi -infected tissue; sapA is also conserved among both class I and class II H. ducreyi strains. We constructed a nonpolar sapA mutant of H. ducreyi 35000HP, designated 35000HP sapA , and compared the percent survival of wild-type 35000HP and 35000HP sapA exposed to several human APs, including α-defensins, β-defensins, and the cathelicidin LL-37. Unlike an H. influenzae sapA mutant, strain 35000HP sapA was not more susceptible to defensins than strain 35000HP was. However, we observed a significant decrease in the survival of strain 35000HP sapA after exposure to LL-37, which was complemented by introducing sapA in trans . Thus, the Sap transporter plays a role in resistance of H. ducreyi to LL-37. We next compared mutant strain 35000HP sapA with strain 35000HP for their ability to cause disease in human volunteers. Although both strains caused papules to form at similar rates, the pustule formation rate at sites inoculated with 35000HP sapA was significantly lower than that of sites inoculated with 35000HP (33.3% versus 66.7%; P = 0.007). Together, these data establish that SapA acts as a virulence factor and as one mechanism for H. ducreyi to resist killing by antimicrobial peptides. To our knowledge, this is the first demonstration that an antimicrobial peptide resistance mechanism contributes to bacterial virulence in humans.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.01014-09
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2010
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  • 7
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    Online Resource
    Expression of Peptidoglycan-Associated Lipoprotein Is Required for Virulence in the Human Model of Haemophilus ducreyi Infection
    American Society for Microbiology ; 2000
    In:  Infection and Immunity Vol. 68, No. 11 ( 2000-11), p. 6441-6448
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 68, No. 11 ( 2000-11), p. 6441-6448
    Abstract: Haemophilus ducreyi expresses a peptidoglycan-associated lipoprotein (PAL) that exhibits extensive homology to Haemophilus influenzae protein 6. We constructed an isogenic PAL mutant (35000HP-SMS4) by the use of a suicide vector that contains lacZ as a counterselectable marker. H. ducreyi 35000HP-SMS4 and its parent, 35000HP, had similar growth rates in broth and similar lipooligosaccharide profiles. 35000HP-SMS4 formed smaller, more transparent colonies than 35000HP and, unlike its parent, was hypersensitive to antibiotics. Complementation of the mutant in trans restored the parental phenotypes. To test whether expression of PAL is required for virulence, nine human volunteers were experimentally infected. Each subject was inoculated with two doses (41 to 89 CFU) of live 35000HP and one dose of heat-killed bacteria on one arm and with three doses (ranging from 28 to 800 CFU) of live 35000HP-SMS4 on the other arm. Papules developed at similar rates at sites inoculated with the mutant or parent but were significantly smaller at mutant-inoculated sites than at parent-inoculated sites. The pustule formation rate was 72% (95% confidence interval [CI], 46.5 to 90.3%) at 18 parent sites and 11% (95% CI, 2.4 to 29.2%) at 27 mutant sites ( P 〈 0.0001). The rates of recovery of H. ducreyi from surface cultures were 8% ( n = 130; 95% CI, 4.3 to 14.6%) for parent-inoculated sites and 0% ( n = 120; 95% CI, 0.0 to 2.5%) for mutant-inoculated sites ( P 〈 0.001). H. ducreyi was recovered from six of seven biopsied parent-inoculated sites and from one of three biopsied mutant-inoculated sites. Confocal microscopy confirmed that the bacteria present in a mutant inoculation site pustule lacked a PAL-specific epitope. Although biosafety regulations precluded our testing the complemented mutant in humans, these results suggest that expression of PAL facilitates the ability of H. ducreyi to progress to the pustular stage of disease.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.68.11.6441-6448.2000
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2000
    detail.hit.zdb_id: 1483247-1
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  • 8
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    Online Resource
    Haemophilus ducreyi Infection Induces Activation of the NLRP3 Inflammasome in Nonpolarized but Not in Polarized Human Macrophages
    American Society for Microbiology ; 2013
    In:  Infection and Immunity Vol. 81, No. 8 ( 2013-08), p. 2997-3008
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 81, No. 8 ( 2013-08), p. 2997-3008
    Abstract: Recognition of microbial infection by certain intracellular pattern recognition receptors leads to the formation of a multiprotein complex termed the inflammasome. Inflammasome assembly activates caspase-1 and leads to cleavage and secretion of the proinflammatory cytokines interleukin-1 beta (IL-1β) and IL-18, which help control many bacterial pathogens. However, excessive inflammation mediated by inflammasome activation can also contribute to immunopathology. Here, we investigated whether Haemophilus ducreyi , a Gram-negative bacterium that causes the genital ulcer disease chancroid, activates inflammasomes in experimentally infected human skin and in monocyte-derived macrophages (MDM). Although H. ducreyi is predominantly extracellular during human infection, several inflammasome-related components were transcriptionally upregulated in H. ducreyi -infected skin. Infection of MDM with live, but not heat-killed, H. ducreyi induced caspase-1- and caspase-5-dependent processing and secretion of IL-1β. Blockage of H. ducreyi uptake by cytochalasin D significantly reduced the amount of secreted IL-1β. Knocking down the expression of the inflammasome components NLRP3 and ASC abolished IL-1β production. Consistent with NLRP3-dependent inflammasome activation, blocking ATP signaling, K + efflux, cathepsin B activity, and lysosomal acidification all inhibited IL-1β secretion. However, inhibition of the production and function of reactive oxygen species did not decrease IL-1β production. Polarization of macrophages to classically activated M1 or alternatively activated M2 cells abrogated IL-1β secretion elicited by H. ducreyi . Our study data indicate that H. ducreyi induces NLRP3 inflammasome activation via multiple mechanisms and suggest that the heterogeneity of macrophages within human lesions may modulate inflammasome activation during human infection.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.00354-13
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2013
    detail.hit.zdb_id: 1483247-1
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  • 9
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    Online Resource
    Haemophilus ducreyi Is Resistant to Human Antimicrobial Peptides
    American Society for Microbiology ; 2007
    In:  Antimicrobial Agents and Chemotherapy Vol. 51, No. 9 ( 2007-09), p. 3391-3393
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 51, No. 9 ( 2007-09), p. 3391-3393
    Abstract: We examined the susceptibility of Haemophilus ducreyi to antimicrobial peptides likely to be encountered in vivo during human infection. H. ducreyi was significantly more resistant than Escherichia coli to the bactericidal effects of all peptides tested. Class I and II H. ducreyi strains exhibited similar levels of resistance to antimicrobial peptides.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00473-07
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2007
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 10
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    Online Resource
    Immunopathogenesis of Haemophilus ducreyi Infection (Chancroid)
    American Society for Microbiology ; 2002
    In:  Infection and Immunity Vol. 70, No. 4 ( 2002-04), p. 1667-1676
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 70, No. 4 ( 2002-04), p. 1667-1676
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.70.4.1667-1676.2002
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2002
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