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Many Gram-negative pathogens produce a cytolethal distending toxin (CDT) with two cell-binding subunits (CdtA + CdtC) and a catalytic CdtB subunit. After adhesion to the plasma membrane of a target cell, CDT moves by retrograde transport to endoplasmic reticulum. CdtB then enters the nucleus where it generates DNA breaks that lead to cell cycle arrest and apoptosis or senescence. CdtA anchors the CDT holotoxin to the plasma membrane and is thought to remain on the cell surface after endocytosis of the CdtB/CdtC heterodimer. Here, we re-examined the potential endocytosis and intracellular transport of CdtA from the Haemophilus ducreyi CDT. We recorded the endocytosis of holotoxin-associated CdtA with a cell-based enzyme-linked immunoabsorbent assay (CELISA) and visualised its presence in the early endosomes by confocal microscopy 10 min after CDT binding to the cell surface. Western blot analysis documented the rapid degradation of internalised CdtA. Most of internalised CdtB and CdtC were degraded as well. The rapid rate of CDT internalisation and turnover, which could explain why CdtA endocytosis was not detected in previous studies, suggests only a minor pool of cell-associated CdtB reaches the nucleus. Our work demonstrates that CDT is internalised as an intact holotoxin and identifies the endosomes as the site of CdtA dissociation from CdtB/CdtC. TAKE AWAYS: During the endocytosis of CDT, CdtA is thought to remain at the cell surface. A cell-based ELISA documented the rapid endocytosis of CdtA. CdtA was visualised in the early endosomes by confocal microscopy. Intracellular CdtA was rapidly degraded, along with most of CdtB and CdtC.

Leshan Xiu,1 Chi Zhang,1 Yamei Li,1 Feng Wang,2 Junping Peng11NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, People’s Republic of China; 2Shenzhen Center for Chronic Disease Control, Shenzhen, People’s Republic of ChinaCorrespondence: Junping PengNHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 6 Rongjing Eastern Street, BDA,Beijing 100176, People’s Republic of ChinaTel/fax +86 106 787 8493Email pengjp@hotmail.comPurpose: Sexually transmitted infections (STIs), representing a major global health problem, are caused by different microbes, including bacteria, viruses, and protozoa. Unfortunately, infections of different sexually transmitted pathogens often present similar clinical symptoms, so it is almost impossible to distinguish them clinically. Therefore, the aim of the current study was to develop a sensitive, multitarget, and high-throughput method that can detect various agents responsible for STIs.Methods: We developed and tested a 23-plex PCR coupled with matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) assay (sexually transmitted infection-mass spectrometry, STI-MS) that simultaneously targets 11 different agents, including 8 most common clinical pathogens related to STIs (HSV-1, HSV-2, Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum, Trichomonas vaginalis, Mycoplasma genitalium, and Haemophilus ducreyi) and 3 controversial microorganisms as pathogens (Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum).Results: The results showed that the STI-MS approach can accurately detect the expected agents, without cross-reaction with other organisms. The limit of detection of each STI-MS assay was ranged from 1.739 to 10.009 copies/reaction, using probit analyses. The verification rate for each target organism of the STI-MS ranged from a minimum of 89.3% to a maximum of 100%, using conventional assays and ultrasensitive digital PCR to confirm the STI-MS-positive results. To further evaluate the clinical performance of this assay, 241 clinical specimens (124 urethral/cervical swabs and 117 urine) were tested in parallel using the STI-MS assay and monoplex real-time PCR for each agent. The overall validation parameters of STI-MS were extremely high including sensitivity (from 85.7% to 100%), specificity (from 92.3% to 100%), PPV (from 50% to 100%), and NPV (from 99.1% to 100%) for each target.Conclusion: STI-MS is a useful high-throughput screening tool for detecting mixed infections of STIs and has great potential for application in large-scale epidemiological programs for specific microorganisms of STI.Keywords: sexually transmitted infections, timely diagnosis, MALDI-TOF mass spectrometry, digital PCR, high-throughput

Cutaneous ulcers (CU) affect approximately 100,000 children in the tropics each year. While two-thirds of CU are caused by Treponema pallidum subspecies pertenue and Haemophilus ducreyi, the cause(s) of the remaining one-third is unknown., Exudative cutaneous ulcers (CU) in yaws-endemic areas are associated with Treponema pallidum subsp. pertenue (TP) and Haemophilus ducreyi (HD), but one-third of CU cases are idiopathic (IU). Using mass drug administration (MDA) of azithromycin, a yaws eradication campaign on Lihir Island in Papua New Guinea reduced but failed to eradicate yaws; IU rates remained constant throughout the campaign. To identify potential etiologies of IU, we obtained swabs of CU lesions (n = 279) and of the skin of asymptomatic controls (AC; n = 233) from the Lihir Island cohort and characterized their microbiomes using a metagenomics approach. CU bacterial communities were less diverse than those of the AC. Using real-time multiplex PCR with pathogen-specific primers, we separated CU specimens into HD-positive (HD+), TP+, HD+TP+, and IU groups. Each CU subgroup formed a distinct bacterial community, defined by the species detected and/or the relative abundances of species within each group. Streptococcus pyogenes was the most abundant organism in IU (22.65%) and was enriched in IU compared to other ulcer groups. Follow-up samples (n = 31) were obtained from nonhealed ulcers; the average relative abundance of S. pyogenes was 30.11% in not improved ulcers and 0.88% in improved ulcers, suggesting that S. pyogenes in the not improved ulcers may be azithromycin resistant. Catonella morbi was enriched in IU that lacked S. pyogenes. As some S. pyogenes and TP strains are macrolide resistant, penicillin may be the drug of choice for CU azithromycin treatment failures. Our study will aid in the design of diagnostic tests and selective therapies for CU.

Yaws is a skin debilitating disease caused by Treponema pallidum subspecies pertenue with most cases reported in children. World Health Organization (WHO) aims at total eradication of this disease through mass treatment of suspected cases followed by an intensive follow-up program. However, effective diagnosis is pivotal in the successful implementation of this control program. Recombinase polymerase amplification (RPA), an isothermal nucleic acid amplification technique offers a wider range of differentiation of pathogens including those isolated from chronic skin ulcers with similar characteristics such as Haemophilus ducreyi (H. ducreyi). We have developed a RPA assay for the simultaneous detection of Treponema pallidum (T. pallidum) and H. ducreyi (TPHD-RPA). The assay demonstrated no cross-reaction with other pathogens and enable detection of T. pallidum and H. ducreyi within 15 min at 42 &deg, C. The RPA assay was validated with 49 clinical samples from individuals confirmed to have yaws by serological tests. Comparing the developed assay with commercial multiplex real-time PCR, the assay demonstrated 94% and 95% sensitivity for T. pallidum and H. ducreyi, respectively and 100% specificity. This simple novel TPHD-RPA assay enables the rapid detection of both T. pallidum and H. ducreyi in yaws-like lesions. This test could support the yaws eradication efforts by ensuring reliable diagnosis, to enable monitoring of program success and planning of follow-up interventions at the community level.

Outbreaks of yaws-like ulcerative skin lesions in children are frequently reported in tropical and sub-tropical countries. The origin of these lesions might be primarily traumatic or infectious; in the latter case, Treponema pallidum subspecies pertenue, the yaws agent, and Haemophilus ducreyi, the agent of chancroid, are two of the pathogens commonly associated with the aetiology of skin ulcers. In this work, we investigated the presence of T. p. pertenue and H. ducreyi DNA in skin ulcers in children living in yaws-endemic regions in Cameroon. Skin lesion swabs were collected from children presenting with yaws-suspected skin lesions during three outbreaks, two of which occurred in 2017 and one in 2019. DNA extracted from the swabs was used to amplify three target genes: the human β2-microglobulin gene to confirm proper sample collection and DNA extraction, the polA gene, highly conserved among all subspecies of T. pallidum, and the hddA gene of H. ducreyi. A fourth target, the tprL gene was used to differentiate T. p. pertenue from the other agents of human treponematoses in polA-positive samples. A total of 112 samples were analysed in this study. One sample, negative for β2-microglobulin, was excluded from further analysis. T. p. pertenue was only detected in the samples collected during the first 2017 outbreak (12/74, 16.2%). In contrast, H. ducreyi DNA could be amplified from samples from all three outbreaks (outbreak 1: 27/74, 36.5%; outbreak 2: 17/24, 70.8%; outbreak 3: 11/13, 84.6%). Our results show that H. ducreyi was more frequently associated to skin lesions in the examined children than T. p. pertenue, but also that yaws is still present in Cameroon. These findings strongly advocate for a continuous effort to determine the aetiology of ulcerative skin lesions during these recurring outbreaks, and to inform the planned mass treatment campaigns to eliminate yaws in Cameroon., Author summary Yaws caused by Treponema pallidum pertenue is one of the most prevalent skin ulcer diseases among children in tropical and sub-tropical countries in Africa and the South-Pacific region. In Cameroon, outbreaks of yaws occur among populations living in remote areas where health infrastructure is lacking. The yaws diagnosis is frequently made clinically, even though rapid and simple serological assays were also introduced to confirm active yaws infection. Lately, studies using molecular amplification assays and performed in the South Pacific and Ghana reported that apart from T. p. pertenue, Haemophiluys ducreyi is also detected in children presenting with yaws-like lesions. This study was performed in the context of the surveillance of yaws in the East and South region of Cameroon. Molecular tools were used to detect and confirm the presence T. p. pertenue in samples suspected of yaws and collected during three outbreaks of ulcerative skin lesions among children in Cameroon. In addition, all samples were analysed for H. ducreyi. We found that H. ducreyi was present in samples from all three outbreaks, but T. p. pertenue was only detected among samples collected during the first outbreak. We concluded that yaws was present in Cameroun but that not all outbreaks of yaws-like skin lesions were attributable to T. p. pertenue infection.

Yaws, a neglected tropical disease caused by the bacterium Treponema pallidum subspecies pertenue, manifests as ulcerative skin lesions. Nucleic acid amplification tests, like loop-mediated isothermal amplification (LAMP), are versatile tools to distinguish yaws from infections that cause similar skin lesions, primarily Haemophilus ducreyi. We developed a novel molecular test to simultaneously detect T. pallidum and H. ducreyi based on mediator displacement LAMP. We validated the T. pallidum and H. ducreyi LAMP (TPHD-LAMP) by testing 293 clinical samples from patients with yaws-like lesions. Compared with quantitative PCR, the TPHD-LAMP demonstrated high sensitivity and specificity for T. pallidum (84.7% sensitivity, 95.7% specificity) and H. ducreyi (91.6% sensitivity, 84.8% specificity). This novel assay provided rapid molecular confirmation of T. pallidum and H. ducreyi DNA and might be suitable for use at the point of care. TPHD-LAMP could support yaws eradication by improving access to molecular diagnostic tests at the district hospital level.

BACKGROUND In many countries, sexually transmitted infections (STIs) are treated syndromically. Thus, patients diagnosed as having genital ulcer disease (GUD) in Zimbabwe receive a combination of antimicrobials to treat syphilis, chancroid, lymphogranuloma venereum (LGV), and genital herpes. Periodic studies are necessary to assess the current etiology of GUD and assure the appropriateness of current treatment guidelines. MATERIALS AND METHODS We selected 6 geographically diverse clinics in Zimbabwe serving high numbers of STI cases to enroll men and women with STI syndromes, including GUD. Sexually transmitted infection history and risk behavioral data were collected by questionnaire and uploaded to a Web-based database. Ulcer specimens were obtained for testing using a validated multiplex polymerase chain reaction (M-PCR) assay for Treponema pallidum (TP; primary syphilis), Haemophilus ducreyi (chancroid), LGV-associated strains of Chlamydia trachomatis, and herpes simplex virus (HSV) types 1 and 2. Blood samples were collected for testing with HIV, treponemal, and nontreponemal serologic assays. RESULTS Among 200 GUD patients, 77 (38.5%) were positive for HSV, 32 (16%) were positive for TP, and 2 (1%) were positive for LGV-associated strains of C trachomatis. No H ducreyi infections were detected. No organism was found in 98 (49.5%) of participants. The overall HIV positivity rate was 52.2% for all GUD patients, with higher rates among women compared with men (59.8% vs 45.2%, P < 0.05) and among patients with HSV (68.6% vs 41.8%, P < 0.0001). Among patients with GUD, 54 (27.3%) had gonorrhea and/or chlamydia infection. However, in this latter group, 66.7% of women and 70.0% of men did not have abnormal vaginal or urethral discharge on examination. CONCLUSIONS Herpes simplex virus is the most common cause of GUD in our survey, followed by T. pallidum. No cases of chancroid were detected. The association of HIV infections with HSV suggests high risk for cotransmission; however, some HSV ulcerations may be due to HSV reactivation among immunocompromised patients. The overall prevalence of gonorrhea and chlamydia was high among patients with GUD and most of them did not meet the criteria for concomitant syndromic management covering these infections.

The surface-enhanced Raman scattering (SERS) has been widely tested for its usefulness in microbiological studies, providing many information-rich spectra which are a kind of 'whole-organism fingerprint' and enabling identification of bacterial species. Here we show, previously not considered, the comprehensive SERS-chemometric analysis of five bacterial pathogens, namely Neisseria gonorrhoeae, Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum, and Haemophilus ducreyi, all being responsible for sexually transmitted diseases (STDs). In the designed biosensor, the direct, intrinsic format of the spectroscopic analysis was adopted for the SERS-based screening of gonorrhea and chlamydiosis due to vibrational analysis of men's urethra swabs. Our experiments demonstrated that the applied method enables identification the individual species of the Neisseria genus with high accuracy. In order to differentiate the sexually transmitted pathogens and to classify the clinical samples of male urethra swabs, three multivariate methods were used. In the external validation the created models correctly classified the men's urethra swabs with prediction accuracy reaching 89% for SIMCA and 100% for PLS-DA. As a result, the developed protocol enables: (i) simple and non-invasive analysis of clinical samples (the collection of urethra swabs specimens could be carried out at different points of care, such as doctor's office); (ii) fast analysis (15 min); (iii) culture-free identification; (iv) sensitive and reliable SERS-based diagnosis of STD. The simplicity of the developed detection procedure, supported by high sensitivity, reproducibility, and specificity, open a new path in the improvement of the point-of-care applications.

Haemophilus ducreyi causes chancroid and is a major cause of cutaneous ulcers in children. Due to environmental reservoirs, both class I and class II H. ducreyi strains persist in cutaneous ulcer regions of endemicity following mass drug administration of azithromycin, suggesting the need for a vaccine. The hemoglobin receptor (HgbA) is a leading vaccine candidate, but its efficacy in animal models is class specific. Controlled human infection models can be used to evaluate vaccines, but only a class I strain (35000HP) has been characterized in this model. As a prelude to evaluating HgbA vaccines in the human model, we tested here whether a derivative of 35000HP containing a class II hgbA allele (FX548) is as virulent as 35000HP in humans. In eight volunteers infected at three sites with each strain, the papule formation rate was 95.8% for 35000HP versus 62.5% for FX548 (P = 0.021). Excluding doses of FX548 that were ≥2-fold higher than those of 35000HP, the pustule formation rate was 25% for 35000HP versus 11.7% for FX548 (P = 0.0053). By Western blot analysis, FX548 and 35000HP expressed equivalent amounts of HgbA in whole-cell lysates and outer membranes. The growth of FX548 and 35000HP was similar in media containing hemoglobin or hemin. By whole-genome sequencing and single-nucleotide polymorphism analysis, FX548 contained no mutations in open reading frames other than hgbA. We conclude that by an unknown mechanism, FX548 is partially attenuated in humans and is not a suitable strain for HgbA vaccine efficacy trials in the model.

Dual RNA sequencing (RNA-seq) offers the promise of determining an interactome at a transcriptional level between a bacterium and the host but has yet to be done on any bacterial infection in human tissue. We performed dual RNA-seq and metabolomics analyses on wounded and infected sites following experimental infection of the arm with H. ducreyi. Our results suggest that H. ducreyi survives in an abscess by utilizing l-ascorbate as an alternative carbon source, possibly taking advantage of host ascorbic acid recycling, and that H. ducreyi also adapts by upregulating genes involved in anaerobic metabolism and inorganic ion and nutrient transport. To our knowledge, this is the first description of an interaction network between a bacterium and the human host at a site of infection., A major gap in understanding infectious diseases is the lack of information about molecular interaction networks between pathogens and the human host. Haemophilus ducreyi causes the genital ulcer disease chancroid in adults and is a leading cause of cutaneous ulcers in children in the tropics. We developed a model in which human volunteers are infected on the upper arm with H. ducreyi until they develop pustules. To define the H. ducreyi and human interactome, we determined bacterial and host transcriptomic and host metabolomic changes in pustules. We found that in vivo H. ducreyi transcripts were distinct from those in the inocula, as were host transcripts in pustule and wounded control sites. Many of the upregulated H. ducreyi genes were found to be involved in ascorbic acid and anaerobic metabolism and inorganic ion/nutrient transport. The top 20 significantly expressed human pathways showed that all were involved in immune responses. We generated a bipartite network for interactions between host and bacterial gene transcription; multiple positively correlated networks contained H. ducreyi genes involved in anaerobic metabolism and host genes involved with the immune response. Metabolomic studies showed that pustule and wounded samples had different metabolite compositions; the top ion pathway involved ascorbate and aldarate metabolism, which correlated with the H. ducreyi transcriptional response and upregulation of host genes involved in ascorbic acid recycling. These data show that an interactome exists between H. ducreyi and the human host and suggest that H. ducreyi exploits the metabolic niche created by the host immune response.

Infections are at their lowest level worldwide, but nongenital cutaneous infections have increased., The global epidemiology of Haemophilus ducreyi infections is poorly documented because of difficulties in confirming microbiological diagnoses. We evaluated published data on the proportion of genital and nongenital skin ulcers caused by H. ducreyi before and after introduction of syndromic management for genital ulcer disease (GUD). Before 2000, the proportion of GUD caused by H. ducreyi ranged from 0.0% to 69.0% (35 studies in 25 countries). After 2000, the proportion ranged from 0.0% to 15.0% (14 studies in 13 countries). In contrast, H. ducreyi has been recently identified as a causative agent of skin ulcers in children in the tropical regions; proportions ranged from 9.0% to 60.0% (6 studies in 4 countries). We conclude that, although there has been a sustained reduction in the proportion of GUD caused by H. ducreyi, this bacterium is increasingly recognized as a major cause of nongenital cutaneous ulcers.

Background In South Africa, treatment of genital ulcer disease (GUD) occurs in the context of syndromic management. GUD aetiological studies have been conducted in Johannesburg since 2007. We report on GUD pathogen prevalence, sero-prevalence of STI co-infections and aetiological trends among GUD patients presenting to a community-based primary healthcare facility in Johannesburg over a 9-year period. Methods and findings GUD surveys were conducted from January to April each year. Consecutive genital ulcers were sampled from consenting adults. Swab-extracted DNA was tested by multiplex real-time PCR assays for herpes simplex virus (HSV), Treponema pallidum (TP), Haemophilus ducreyi (HD) and Chlamydia trachomatis (CT). HSV-positive DNA extracts were further subtyped into HSV-1 and HSV-2 using a commercial PCR assay; CT-positive extracts were tested with an in-house PCR assay specific for serovars L1-L3 (lymphogranuloma venereum). Sera were tested for HIV, HSV-2, and syphilis co-infections. Giemsa-stained ulcer smears were screened for Klebsiella granulomatis by microscopy. Data were analysed with STATATM version 14. Of 771 GUD specimens, 503 (65.2%) had a detectable pathogen: HSV 468 (60.7%); TP 30 (3.9%); CT L1-3 7 (0.9%); HD 4 (0.5%). No aetiological agents were detected in 270 (34.8%) ulcer specimens. Seroprevalence rates were as follows: HIV 61.7%; HSV-2 80.2% and syphilis 5.8%. There was a strong association between GUD pathogen detection and HIV seropositivity (p < 0.001); 68% of cases caused by HSV were co-infected with HIV. There was a significant decline in the relative prevalence of ulcer-derived HSV over time, predominantly from 2013–2015 (p-value for trend = 0.023); and a trend towards a decrease in the HIV seropositivity rate (p-value for trend = 0.209). Conclusions HSV remains the leading cause of pathogen-detectable GUD in South Africa. The prevalence of HIV co-infection among GUD patients is high, underlining the importance of linkage to universal HIV testing and treatment in primary healthcare settings.

One of the most common groups of infections is sexually transmitted diseases (STDs), and they have posed a significant medical and public health problem worldwide. Over 1 million new cases are documented each day. With a heavy burden of disease in the population, significant resources have been applied to the detection and treatment of STDs. More manual and traditional methods have been replaced with cutting-edge molecular tests for detecting these organisms. Non-amplification (e.g., nucleic acid hybridization), signal amplification (e.g., Digene Hybrid Capture), and target amplification (e.g., PCR and transcription-mediated amplification) nucleic acid techniques have been applied to STD diagnostics which has greatly improved throughput, sensitivity, specificity, and turnaround time for laboratory diagnosis. This has improved the way we treat the patient and how we address public health disease control and prevention. This chapter reviews the molecular diagnostic techniques for detection of bacterial (Treponema pallidum, Haemophilus ducreyi, Chlamydia trachomatis, Neisseria gonorrhea, Mycoplasma and Ureaplasma), Trichomonas vaginalis, and Herpes simplex virus STD infections.

Haemophilus ducreyi is the causative agent of the sexually transmitted genital ulcer disease chancroid. Strains of H. ducreyi are grouped in two classes (I and II) based on genotypic and phenotypic differences, including those found in DsrA, an outer membrane protein belonging to the family of multifunctional trimeric autotransporter adhesins. DsrA is a key serum resistance factor of H. ducreyi that prevents binding of natural IgM at the bacterial surface and functions as an adhesin to fibronectin, fibrinogen, vitronectin, and human keratinocytes. Monoclonal antibodies (MAbs) were developed to recombinant DsrA (DsrA(I)) from prototypical class I strain 35000HP to define targets for vaccine and/or therapeutics. Two anti-DsrAI MAbs bound monomers and multimers of DsrA from genital and non-genital/cutaneous H. ducreyi strains in a Western blot and reacted to the surface of the genital strains; however, these MAbs did not recognize denatured or native DsrA from class II strains. In a modified extracellular matrix protein binding assay using viable H. ducreyi, one of the MAbs partially inhibited binding of fibronectin, fibrinogen, and vitronectin to class I H. ducreyi strain 35000HP, suggesting a role for anti-DsrA antibodies in preventing binding of H. ducreyi to extracellular matrix proteins. Standard ELISA and surface plasmon resonance using a peptide library representing full-length, mature DsrAI revealed the smallest nominal epitope bound by one of the MAbs to be MEQNTHNINKLS. Taken together, our findings suggest that this epitope is a potential target for an H. ducreyi vaccine.

Adherence of pathogens to cellular targets is required to initiate most infections. Defining strategies that interfere with adhesion is therefore important for the development of preventative measures against infectious diseases. As an adhesin to host extracellular matrix proteins and human keratinocytes, the trimeric autotransporter adhesin DsrA, a proven virulence factor of the Gram-negative bacterium Haemophilus ducreyi, is a potential target for vaccine development. A recombinant form of the N-terminal passenger domain of DsrA from H. ducreyi class I strain 35000HP, termed rNT-DsrAI, was tested as a vaccine immunogen in the experimental swine model of H. ducreyi infection. Viable homologous H. ducreyi was not recovered from any animal receiving four doses of rNT-DsrAI administered with Freund's adjuvant at two-week intervals. Control pigs receiving adjuvant only were all infected. All animals receiving the rNT-DsrAI vaccine developed antibody endpoint titers between 3.5 and 5 logs. All rNT-DsrAI antisera bound the surface of the two H. ducreyi strains used to challenge immunized pigs. Purified anti-rNT-DsrAI IgG partially blocked binding of fibrinogen at the surface of viable H. ducreyi. Overall, immunization with the passenger domain of the trimeric autotransporter adhesin DsrA accelerated clearance of H. ducreyi in experimental lesions, possibly by interfering with fibrinogen binding.

Chancroid, caused by Haemophilus ducreyi, has declined in importance as a sexually transmitted pathogen in most countries where it was previously endemic. The global prevalence of chancroid is unknown as most countries lack the required laboratory diagnostic capacity and surveillance systems to determine this. H. ducreyi has recently emerged as a cause of chronic skin ulceration in some South Pacific islands. Although no antimicrobial susceptibility data for H. ducreyi have been published for two decades, it is still assumed that the infection will respond successfully to treatment with recommended cephalosporin, macrolide or fluoroquinolone-based regimens. HIV-1-infected patients require careful follow-up due to reports of treatment failure with single dose regimens. Buboes may need additional treatment with either aspiration or excision and drainage.

We report the first case of chancroid seen at our clinic in 14 years. It was diagnosed by nuclear acid amplification test in a male patient returning from Madagascar. Although the disease is considered on the verge of disappearance even in tropical countries, its real potential for reemergence – due to new strains of Haemophilus ducreyi, underreporting and a lack of widespread use of molecular testing – could be underestimated.

Haemophilus ducreyi causes chancroid and has recently been shown to be a significant cause of cutaneous lesions in tropical or subtropical regions where yaws is endemic. Here, we report the draft genome assemblies for 11 cutaneous strains of Haemophilus ducreyi , isolated from children in Vanuatu and Ghana.

Haemophilus ducreyi has recently emerged as a leading cause of cutaneous ulcers in the yaws-endemic areas of Papua New Guinea and other South Pacific islands. Here, we report the draft genome sequence of the H. ducreyi strain AUSPNG1, isolated from a cutaneous ulcer of a child from Papua New Guinea.

Chancroid, a sexually transmitted genital ulcer disease caused by the Gram-negative bacterium Haemophilus ducreyi, facilitates the acquisition and transmission of HIV. An effective vaccine against chancroid has not been developed. In this preliminary study, the gene encoding the H. ducreyi outer membrane hemoglobin receptor HgbA was cloned into the plasmid pTETnir15. The recombinant construct was introduced into the attenuated Salmonella typhimurium SL3261 strain and stable expression was induced in vitro under anaerobic conditions. The vaccine strain was delivered into the temperature-dependent rabbit model of chancroid by intragastric immunization as a single dose, or as three doses administered at two-weekly intervals. No specific antibody to HgbA was elicited after either dose schedule. Although the plasmid vector survived in vivo passage for up to 15 days following single oral challenge, HgbA expression was restricted to plasmid isolates recovered one day after immunization. Rabbits inoculated with the 3-dose booster regimen achieved no protective immunity from homologous challenge. These results emphasize that refinements in plasmid design to enhance a durable heterologous protein expression are necessary for the development of a live oral vaccine against chancroid.

This chapter outlines the need for, and application of, molecular tests for Haemophilus ducreyi, Treponema pallidum, and Mycoplasma genitalium, three sexually transmitted diseases (STDs) pathogens for which commercial molecular tests are not currently available. H. ducreyi and T. pallidum are the causative agents of chancroid and syphilis, respectively, which along with herpes simplex virus (HSV) are responsible for the majority of genital ulcer disease (GUD) cases worldwide. The first PCR assays specific for M. genitalium were simultaneously developed in two laboratories and provided a means of detecting M. genitalium in patient specimens. The authors await further application of these quantitative PCR assays to assess other aspects of M. genitalium infection such as the association of M. genitalium burden in cervical, urine, and vaginal specimens and their association with signs and symptoms of infection at these sites. Unlike most PCRs, TMA assays target rRNA, which is present in multiple copies per cell, thus potentially increasing both the analytical and the clinical sensitivity of M. genitalium detection. Similarly, PCR and TMA assays for M. genitalium have allowed studies defining the association of this emerging pathogen with reproductive tract disease in both men and women. Undoubtedly other, previously uncultivated organisms colonizing the reproductive tract will be detected in the future. Their identification and the subsequent development of specific PCR assays and treatment regimens will expand one's knowledge of reproductive tract pathogens.

Haemophilus ducreyi , the etiological agent of chancroid, has a strict requirement for heme, which it acquires from its only natural host, humans. Previously, we showed that a vaccine preparation containing the native hemoglobin receptor HgbA purified from H. ducreyi class I strain 35000HP (nHgbA I ) and administered with Freund's adjuvant provided complete protection against a homologous challenge. In the current study, we investigated whether nHgbA I dispensed with monophosphoryl lipid A (MPL), an adjuvant approved for use in humans, offered protection against a challenge with H. ducreyi strain 35000HP expressing either class I or class II HgbA (35000HP hgbA I and 35000HP hgbA II , respectively). Pigs immunized with the nHgbA I /MPL vaccine were protected against a challenge from homologous H. ducreyi strain 35000HP hgbA I but not heterologous strain 35000HP hgbA II , as evidenced by the isolation of only strain 35000HP hgbA II from nHgbA I -immunized pigs. Furthermore, histological analysis of the lesions showed striking differences between mock-immunized and nHgbA I -immunized animals challenged with strains 35000HP hgbA I but not those challenged with strain 35000HP hgbA II . Mock-immunized pigs were not protected from a challenge by either strain. The enzyme-linked immunosorbent assay (ELISA) activity of the nHgbA I /MPL antiserum was lower than the activity of antiserum from animals immunized with the nHgbA I /Freund's vaccine; however, anti-nHgbA I from both studies bound whole cells of 35000HP hgbA I better than 35000HP hgbA II and partially blocked hemoglobin binding to nHgbA I . In conclusion, despite eliciting lower antibody ELISA activity than the nHgbA I /Freund's, the nHgbA I /MPL vaccine provided protection against a challenge with homologous but not heterologous H. ducreyi , suggesting that a bivalent HgbA vaccine may be needed.

A sexually transmitted disease (STD) is a common infection caused by various pathogens. Many other bacteria and viruses are associated with STDs. Infection of bacterial STD agents is sometimes not accompanied by symptoms. If an infected person who has no symptoms is not tested, infection control of an STD agent will fail and the infection may then be transmitted to a new person through sexual contact. Therefore, development of proper detection methods is important in control of STDs. In this study, we developed a microarray to detect infection of bacterial STD agents. We designed specific primers and probes for each STD pathogen and then hybridized with specific target amplified DNA. In conclusion, a DNA microarray-based detection method is ideal for detection of STDs because it offers simultaneous multi-targeting as well as fast and high-throughput detection.

Chancroid is a sexually transmitted infection (STI) caused by the Gram-negative bacterium Haemophilus ducreyi . The control of chancroid is difficult and the only current available treatment is antibiotic therapy; however, antibiotic resistance has been reported in endemic areas. Owing to recent outbreaks of STIs worldwide, it is important to keep searching for new treatment strategies and preventive measures. Here, we applied reverse vaccinology and subtractive genomic approaches for the in silico prediction of potential vaccine and drug targets against 28 strains of H. ducreyi . We identified 847 non-host homologous proteins, being 332 exposed/secreted/membrane and 515 cytoplasmic proteins. We also checked their essentiality, functionality and virulence. Altogether, we predicted 13 candidate vaccine targets and three drug targets, where two vaccines (A01_1275, ABC transporter substrate-binding protein; and A01_0690, Probable transmembrane protein) and three drug targets (A01_0698, Purine nucleoside phosphorylase; A01_0702, Transcription termination factor; and A01_0677, Fructose-bisphosphate aldolase class II) are harboured by pathogenicity islands. Finally, we applied a molecular docking approach to analyse each drug target and selected ZINC77257029, ZINC43552589 and ZINC67912117 as promising molecules with favourable interactions with the target active site residues. Altogether, the targets identified here may be used in future strategies to control chancroid worldwide.

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.

Chancroid is an extremely infectious sexually transmitted disease (STD) caused by the bacterium Haemophilus ducreyi, prevalent in Africa, United States and in some parts of South Asia. Chancroid has been recognized as a cofactor for human immunodeficiency virus (HIV) transmission. So, there is a requirement to develop an efficient drug to combat chancroid, which can also diminish the HIV prevalence in those populations where chancroid is a prime source for HIV infection. The availability of the complete proteome information of H. ducreyi help enabled in silico analysis for identification of potential vaccine candidates and drug targets. Our study revealed 1226 proteins in H. ducreyi to be nonhomologous with human proteome. Screening these proteins using the Database of Essential Genes (DEG) resulted in the identification of 451 essential proteins. Analysis of the identified essential proteins, using the KEGG Automated Annotation Server (KAAS), revealed 40 proteins of H. ducreyi as potential drug targets as they are involved in pathogen specific metabolic pathways. Subcellular localization prediction of these 451 essential proteins revealed that 11 proteins lie on the outer membrane of the pathogen which could be potential vaccine candidates. Functional family prediction for the 50 putative uncharacterized essential proteins of H. ducreyi by SVM-Prot web server revealed that out of 50, 3 proteins as transmembrane proteins, which may be potential drug targets. Identification of potential inhibitors against these targets through virtual screening may consequence in detection of novel lead compounds effective against H. ducreyi to combat chancroid.

Haemophilus ducreyi is a gram-negative coccobacillus and the causative agent of the sexually transmitted genital ulcer disease (GUD) chancroid (1, 8). Globally, chancroid is a significant sexually transmitted disease, with more than 6 million cases reported in 1997 (60). In the United States, several outbreaks were reported between 1980 and 2000 (24, 36, 51), but since then the number of cases has greatly diminished, and today the soft chancres characteristic of H. ducreyi infection occur only in isolated cases that are typically associated with the sex trade industry (57). Chancroid is endemic in some developing countries in Africa, Asia, and South America, where it accounts for almost half of all GUD cases, although these numbers could be higher as H. ducreyi cases remain poorly documented (55, 57). GUD is a recognized cofactor for human immunodeficiency virus acquisition and transmission (25, 37), and a better understanding of H. ducreyi pathogenesis is necessary to allow a rational approach to the identification of vaccine candidates that could be used to prevent chancroid. H. ducreyi is a strict human pathogen, and it is likely that during the different stages of ulcer production (i.e., progression of a papule into a pustule followed by frank ulceration [1, 8, 50]), this pathogen controls gene expression to enhance its growth and to evade the host immune system. Information about regulatory networks that might control the expression of H. ducreyi virulence factors is very limited at present. Although nucleotide sequence analysis of the H. ducreyi 35000HP genome (GenBank accession no. NC002940) revealed the presence of several genes encoding predicted proteins with homology to known bacterial regulators, to date, only the fur gene (12), the groE operon (44), and the dnaK-dnaJ operon (43) have been studied in any detail. The LspA1, LspA2, and LspB proteins constitute a two-partner secretion system in H. ducreyi (65). Expression of either LspA1 or LspA2 has been shown to be necessary for H. ducreyi to inhibit phagocytosis by immune cells in vitro (61). LspA1 and LspA2 have 86% identity (64), and their respective open reading frames (ORFs) are located very distant from each other in the H. ducreyi chromosome. These proteins are also required for full virulence of this pathogen in both the human (30) and the temperature-dependent rabbit (63) models of experimental H. ducreyi infection. Previous studies in our laboratory indicated that wild-type H. ducreyi apparently expressed more LspA1 than LspA2 and that a lspA1 mutant expressed increased amounts of LspA2 (63). Taken together, these results suggested that these two proteins might be under the control of different, unidentified regulatory factors. In the present study, we report that inactivation of the gene encoding the response regulator CpxR resulted in increased expression of both LspB and LspA2, suggesting that the H. ducreyi lspB-lspA2 operon is under the control of the CpxRA two-component regulatory system (18, 46, 47) homolog present in H. ducreyi.

Summary Multiple pathogenic Gram-negative bacteria produce cytolethal-distending toxins (CDTs). CDT is typically composed of three subunits: the catalytic subunit CdtB has DNase I-like activity, whereas CdtA and CdtC are binding proteins for delivering CdtB into target cells. Translocation of CdtB to the nucleus induces genotoxic effects on host DNA, triggering DNA repair cascades that lead to cell cycle arrest and eventual cell death. Several lines of evidence indicate that this toxin contributes to the pathogenicity of CDT-producing bacteria in vivo. Helicobacter hepaticus and Campylobacter jejuni CDTs are essential for persistent infection of the gastrointestinal tract and increase the severity of mucosal inflammation or liver disease in susceptible mouse strains. Haemophilus ducreyi CDT may contribute to the pathogenesis of chancroid in rabbits. Recently, H. hepaticus CDT has been shown to play a crucial role in promoting the progression of infectious hepatitis to pre-malignant, dysplastic lesions via activation of a pro-inflammatory NF-κB pathway and increased proliferation of hepatocytes, providing the first evidence that CDT has carcinogenic potential in vivo. Thus, both in vitro and in vivo data indicate that CDT is a bacterial virulence factor.

Haemophilus ducreyi causes the genital ulcer disease (GUD) chancroid. Chancroid remains prevalent in developing countries, where HIV infection is endemic [1], and facilitates HIV acquisition and transmission [1, 2]. HIV RNA level, or viral load (VL), in the urogenital compartment or its surrogate, plasma VL, is the major predictor of the sexual transmission of HIV [3]. VL is highest during acute HIV infection, during the late stages of AIDS, and during coinfections with other sexually transmitted pathogens [3]. Chancroid is estimated to increase the risk of HIV acquisition by 25-fold [4]. Simulation models estimate that ~80%–90% of the HIV infections that occurred during the first decade of the pandemic in sub-Saharan Africa were mostly attributable to ulcerative sexually transmitted diseases [4, 5]. Men with HIV infection, nongonococcal urethritis (NGU), and GUD in a country in which chancroid is endemic have increased semen VLs versus men with NGU but no GUD, and semen VLs are reduced with appropriate antibiotic therapy for NGU and GUD [6]. However, no prospective studies have examined the effect of chancroid on VL. To study the biology of H. ducreyi, we developed a model in which bacteria are delivered to the skin of the upper arms of healthy adult volunteers by puncture wound [7]. Experimental infection closely mimics the initial stages and histopathology of natural chancroid [7–12]. In the human infection model, H. ducreyi colocalizes with polymorphonuclear neutrophils (PMNs), macrophages, and fibrin [13]; remains extracellular; and evades phagocytosis [14]. These relationships are maintained in natural ulcers [15]. Although atypical presentations of chancroid in HIV-infected persons were initially reported [16, 17], subsequent studies have shown little difference in the clinical course and response to antibiotics between HIV-infected and HIV-seronegativepersons [18–20]. The histopathology of chancroid in HIV-infected and HIV-seronegative persons is similar [11, 21]. We reasoned that experimental infection of HIV-infected volunteers would be safe because the organism is extracellular and impaired T cell–mediated immunity should not have a major effect on the course of experimental infection. Here, we studied interactions between H. ducreyi and HIV by experimentally infecting HIV-infected volunteers with H. ducreyi. We hypothesized that the clinical course and lesional infiltrate in HIV-infected persons would be similar to that seen in HIV-seronegative persons. Because experimental infection in HIV-seronegative persons does not cause systemic immune responses [8], we hypothesized that experimental infection would not lead to sustained increases in HIV replication or the lowering of CD4+ cell counts in the systemic compartment. We also hypothesized that experimental infection would recruit latently infected CD45RO+CD4+ cells and macrophages to the skin, activate these cells, and cause them to produce virus locally in treatment-naive subjects but not in subjects receiving highly active antiretroviral therapy (HAART). This is the first study to prospectively examine the effect of chancroid on HIV replication and CD4+ cell count, albeit in an experimental setting.

The influence of the skin microbiota on host susceptibility to infectious agents is largely unexplored. The skin harbors diverse bacterial species that may promote or antagonize the growth of an invading pathogen. We developed a human infection model for Haemophilus ducreyi in which human volunteers are inoculated on the upper arm. After inoculation, papules form and either spontaneously resolve or progress to pustules. To examine the role of the skin microbiota in the outcome of H. ducreyi infection, we analyzed the microbiomes of four dose-matched pairs of “resolvers” and “pustule formers” whose inoculation sites were swabbed at multiple time points. Bacteria present on the skin were identified by amplification and pyrosequencing of 16S rRNA genes. Nonmetric multidimensional scaling (NMDS) using Bray-Curtis dissimilarity between the preinfection microbiomes of infected sites showed that sites from the same volunteer clustered together and that pustule formers segregated from resolvers (P = 0.001, permutational multivariate analysis of variance [PERMANOVA]), suggesting that the preinfection microbiomes were associated with outcome. NMDS using Bray-Curtis dissimilarity of the endpoint samples showed that the pustule sites clustered together and were significantly different than the resolved sites (P = 0.001, PERMANOVA), suggesting that the microbiomes at the endpoint differed between the two groups. In addition to H. ducreyi, pustule-forming sites had a greater abundance of Proteobacteria, Bacteroidetes, Micrococcus, Corynebacterium, Paracoccus, and Staphylococcus species, whereas resolved sites had higher levels of Actinobacteria and Propionibacterium species. These results suggest that at baseline, resolvers and pustule formers have distinct skin bacterial communities which change in response to infection and the resultant immune response., IMPORTANCE Human skin is home to a diverse community of microorganisms, collectively known as the skin microbiome. Some resident bacteria are thought to protect the skin from infection by outcompeting pathogens for resources or by priming the immune system’s response to invaders. However, the influence of the skin microbiome on the susceptibility to or protection from infection has not been prospectively evaluated in humans. We characterized the skin microbiome before, during, and after experimental inoculation of the arm with Haemophilus ducreyi in matched volunteers who subsequently resolved the infection or formed abscesses. Our results suggest that the preinfection microbiomes of pustule formers and resolvers have distinct community structures which change in response to the progression of H. ducreyi infection to abscess formation.

Sexually transmitted infections (STIs) comprise more than 30 different bacterial, viral, protozoal, and yeast infections acquired during sexual intercourse and therefore directly afflicting the genital tracts or gaining systemic access across the genital mucosae. Effective vaccines have been developed against only two viral STIs (hepatitis B and human papillomavirus). For most STIs, the nature of the immune responses induced and the parameters of immunity against them are poorly understood. However, progress has been made in comprehending responses especially against Neisseria gonorrhoeae, Chlamydia trachomatis, Haemophilus ducreyi, and Candida albicans. An emerging aspect is that these well-adapted human pathogens exploit the unique characteristics of immunity in the reproductive tracts, eliciting responses favorable to their own survival and suppressing those that would be detrimental to them. Elucidation of the mechanisms whereby STI pathogens manipulate the host's immune responses will lead to novel approaches for therapy and vaccine development.

Background. Genital ulcer disease (GUD) is commonly caused by pathogens for which suitable therapies exist, but clinical and laboratory diagnoses may be problematic. This collaborative project was undertaken to address the need for a rapid, economical, and sensitive approach to the detection and diagnosis of GUD using noninvasive techniques to sample genital ulcers. Methods. The genital ulcer disease multiplex polymerase chain reaction (GUMP) was developed as an inhouse nucleic acid amplification technique targeting serious causes of GUD, namely, herpes simplex viruses (HSVs), Haemophilus ducreyi, Treponema pallidum, and Klebsiella species. In addition, the GUMP assay included an endogenous internal control. Amplification products from GUMP were detected by enzyme linked amplicon hybridization assay (ELAHA). Results. GUMP-ELAHA was sensitive and specific in detecting a target microbe in 34.3% of specimens, including 1 detection of HSV-1, three detections of HSV-2, and 18 detections of T. pallidum .N oH. ducreyi has been detected in Australia since 1998, and none was detected here. No Calymmatobacterium (Klebsiella) granulomatis was detected in the study, but there were 3 detections during ongoing diagnostic use of GUMP-ELAHA in 2004 and 2005. The presence of C. granulomatis was confirmed by restriction enzyme digestion and nucleotide sequencing of the 16S rRNA gene for phylogenetic analysis. Conclusions. GUMP-ELAHA permitted comprehensive detection of common and rare causes of GUD and incorporated noninvasive sampling techniques. Data obtained by using GUMP-ELAHA will aid specific treatment of GUD and better define the prevalence of each microbe among at-risk populations with a view to the eradication of chancroid and donovanosis in Australia. Genital ulcer disease (GUD) is commonly caused by pathogens against which suitable therapies exist but for which clinical and laboratory diagnoses may be problematic. The 3 most common etiological agents of genital lesions are the herpes simplex viruses (HSVs), Treponema pallidum subspecies pallidum (a gram-negative

Chancroid, formerly a major cause of the genital ulcer disease syndrome, remains an important cofactor in both the transmission and acquisition of HIV-1 infection. Those countries with the greatest burden of HIV also have some of the highest prevalence rates of chancroid worldwide. The diagnosis of chancroid, caused by the fastidious bacterium Haemophilus ducreyi, is both expensive and difficult in many resource-poor areas. These areas of the world use syndromic management to treat genital ulcers and such an approach has proven effective in reducing rates of bacterial genital ulcer diseases. There are currently inexpensive and effective single-dose therapies available to treat chancroid. Single-dose regimens, given at first presentation, improve compliance and reduce the risk of sexually transmitted infections. Bacterial resistance to several antimicrobial agents has increased over the years and remains a continued threat to effective antimicrobial therapy. Follow-up of cases, and partner notification and treatment is carried out to limit reinfection and onward transmission of chancroid. Patients with coexistent HIV may be particularly at risk of failing single-dose therapy and should therefore be reviewed wherever possible.

To determine the aetiology of genital ulcer disease (GUD) and its association with HIV infection in the mining community of Carletonville, South Africa, from two cross sectional surveys of consecutive men presenting with genital lesions during October 1993 to January 1994 and July to November 1998.A multiplex polymerase chain reaction (M-PCR) assay combined with amplicon detection was used to identify DNA specific sequences of Treponema pallidum, herpes simplex virus (HSV), and Haemophilus ducreyi. A real time PCR assay was used to differentiate between HSV-1 and HSV-2.M-PCR detected T pallidum, HSV, and H ducreyi in 10.3%, 17.2%, and 69.4% of 232 GUD patients during 1993-4 and in 12.4%, 36.0%, and 50.5% of 186 GUD patients in 1998. The proportion of patients with more than one agent increased significantly from 7.3% (17/232) in 1993-4 to 16.7% (31/186) in 1998 (p0.01). HSV-2 was detected in a higher proportion of ulcer specimens from HIV infected patients than in specimens from HIV uninfected patients during both time periods (1993-4: 26.2% v 6.7%, p0.001; 1998: 42.1% v 29.6%, p0.09).Based on two cross sectional surveys, 4 years apart, chancroid remained the leading cause of GUD in men who presented at the STD clinic with genital ulcers in the mining community of Carletonville, South Africa. The relative prevalence of primary syphilis has remained low. However, HSV-2 has emerged as a more significant cause of GUD and the proportion of GUD patients infected with more than one agent also increased significantly. HSV-2 DNA was detected in a significantly higher proportion of ulcer specimens from HIV positive patients than from HIV negative patients. No association was found between HIV infection status and the relative prevalence of chancroid or syphilis.

Background: The etiological agent is usually not established in cases of genital ulcer disease (GUD) in Tanzania, since diagnosis and treatment of this disease are based mainly on clinical rather than micro-biologic parameters. GUD increases the risk of infection with HIV. However, the association between specific GUD infections and HIV infection has not been fully investigated. Goal: The goal was to determine the etiology of GUD and the prevalence of HIV infection in patients with GUD in urban areas of Tanzania. Study Design: A total of 102 clinical specimens were collected from 52 and 50 patients with GUD in Dar es Salaam and Mbeya, respectively, and from 93 patients with genital discharge in a cross-sectional study. Two polymerase chain reaction (PCR) assays were used to identify either a single target DNA or all three DNAs of the major causes of GUD: Haemophilus ducreyi, Treponema pallidum, and herpes simplex virus type 2 (HSV-2). The sera from all patients were tested for antibodies to HIV and T pallidum. Results: In Dar es Salaam, DNA from HSV-2, H ducreyi, and T pallidum was detected in 63%, 13%, and 2%, respectively, of the 52 genital ulcer specimens. The corresponding figures in Mbeya were 34%, 10%, and 0% of 50 specimens. Overall, 9% of the 102 patients with GUD were infected with both HSV-2 and H ducreyi, and 39/102 genital ulcer specimens (38%) were negative for the DNA of all three pathogens. The HIV infection rates among GUD patients were 46% and 52% in Dar es Salaam and Mbeya, respectively; among the non-GUD patients, the corresponding rates were 35% and 45%, respectively. The HIV infection rate in Dar es Salaam was significantly higher among women (11/14; 78%) than among men (13/38; 34%) (P = 0.004). Among the HIV-seropositive GUD patients, 71% and 46% (P < 0.003) were coinfected with HSV-2 in Dar es Salaam and Mbeya, respectively. Furthermore, women with HSV-2 in Dar es Salaam were significantly more likely to be HIV-infected than men (60% versus 39%; P ≤ 0.006). T pallidum antibodies were detected in 27 (26%) of the 102 GUD patients and 16 (17%) of the 93 non-GUD patients. Conclusion: HSV-2 was the most commonly identified agent in the genital ulcer specimens in two urban STD clinics in Tanzania. The prevalence of HIV was high among the STD patients. HSV-2 was detected at significantly higher rates among HIV-seropositive than HIV-seronegative patients with GUD in both Dar es Salaam and Mbeya.

Chancroid, caused by the gram-negative bacterium Haemophilus ducreyi (for reviews, see references 2, 47, and 60), is one of the sexually transmitted genital ulcer diseases. Although outbreaks are more prevalent in developing countries, sporadic outbreaks have occurred in the United States. Up to 50% of patients visiting sexually transmitted disease clinics in sub-Saharan Africa may have chancroid (12, 23). Additionally, it is an independent risk factor for the heterosexual transmission of human immunodeficiency virus (HIV) (34; F. A. Plummer, M. A. Wainberg, P. Plourde, P. Jessamine, L. J. DCosta, I. A. Wamola, and A. R. Ronald, Letter, J. Infect. Dis. 161:810-811, 1990); therefore, the interest in chancroid has recently intensified. In the last 10 years, several laboratories have begun to define the molecular biology of this pathogen. The study of virulence factors, the body's immune response to infection, and potential vaccines for H. ducreyi have all made significant contributions to the understanding of this bacterium (3-10, 13-16, 22, 24, 26-28, 32, 33, 36, 38, 39, 46, 50, 53, 54, 59, 61, 64). With the genome sequence completed, the process of annotation will, undoubtedly, further accelerate progress on this strictly human pathogen (www.microbial-pathogenesis.org). At present, there are several laboratory methods for the diagnosis of chancroid, including Gram stain, culture, and PCR. Various rates of sensitivity have been reported for the Gram stain, all approximating 50% (51, 57). The presence of other organisms in the polymicrobial chancroid ulcer reduces the specificity of the Gram stain, as these bacteria may be confused with H. ducreyi morphologically, especially by inexperienced personnel. Thus, the Gram stain has little clinical utility in the diagnosis of chancroid. Before the advent of reliable PCR methods, culture was the widely accepted standard of laboratory diagnosis (43, 57). H. ducreyi is a fastidious bacterium that has an absolute requirement for heme because it lacks a heme biosynthetic pathway (60); therefore, use of a special medium is required. Many strains require the addition of fetal bovine serum for growth. Furthermore, H. ducreyi requires a CO2 or microaerophilic atmosphere, and its optimal growth temperature (33°C) is lower than those of most human pathogens, mandating an additional dedicated incubator if it is to be routinely cultured. On primary isolation, small colonies of H. ducreyi usually appear after 2 to 3 days of incubation. Because ulcers are often secondarily contaminated with other more rapidly growing bacteria, cultures can be lost due to contamination (41). Culture is relatively insensitive, with the sensitivity ranging between 56 and 84% (25). The use of more than one primary isolation medium improves isolation rates, but not substantially (25). Culture is thought to be 100% specific; however, traditional biochemical identification of a presumptive H. ducreyi isolate is problematic due to its relative biochemical inertness. Furthermore, H. ducreyi fails to grow on standard biochemical media used to test other bacteria. Thus, for culturing, optimum sensitivity and specificity require microbiologists with specific training and experience with H. ducreyi. Such personnel are lacking both in underdeveloped areas where the organism is endemic and in developed countries such as the United States where it is not endemic. Two advantages that culture offers are the abilities to perform sensitivity testing of isolates and strain typing for epidemiological studies. Despite its limitations, culture will remain a valuable tool in the future. As technology has improved, PCR has become the most sensitive method for the diagnosis of chancroid (19, 40, 44, 58; K. A. Orle et al., Abstr. 94th Gen. Meet. Am. Soc. Microbiol. 1995, abstr. C-247, p. 43, 1995). It has a sensitivity approaching 100%. Although some surmise that false-positive results occur, this has been very difficult to prove. To date, PCR studies are done in laboratories remote from the clinic setting and therefore are not useful for establishing a diagnosis in a time frame that would benefit patient treatment. At present, multiplex PCR is not available for commercial use; rather, it is used for limited research purposes only. The need to maintain trained personnel to perform and interpret cultures and PCR in the resource-poor settings where chancroid is endemic makes these tests economically prohibitive. Furthermore, the costs of media, equipment, and reagents for culture and PCR are considerable. Because of these limitations, culture and PCR in their current formats are not suitable for on-site, immediate detection of H. ducreyi in clinical specimens in areas where the organism is endemic. Therefore, a stable, inexpensive, and rapid test that is simple to perform and interpret at the bedside would be a valuable tool in chancroid control, so long as it maintains its sensitivity and specificity. The immunochromatography (IC) test described in this report is based on novel monoclonal antibodies (MAbs) to the hemoglobin receptor, HgbA, which is an abundant outer membrane protein (OMP) that is required for the acquisition of heme from hemoglobin (26, 27; C. Elkins, unpublished data, 1999). The ability of H. ducreyi to obtain heme from hemoglobin is required for pustule formation. An isogenic hgbA mutant which is unable to utilize hemoglobin was unable to form pustules in a human experimental model of infection (5). As HgbA is conserved in geographically diverse isolates, we developed an IC test based on these MAbs to this protein. In the present report, we describe progress in the initial development of a rapid diagnostic test for H. ducreyi.

Haemophilus ducreyi is the causative agent of the genital ulcer disease chancroid. Chancroid is common in developing countries and facilitates human immunodeficiency virus transmission. In this review, the clinical features, epidemiology, and prospects for disease control are discussed in the context of experimental and natural infection of humans.

Since the early 1980s the Bahamas has experienced sequential epidemics of freebase/crack cocaine use genital ulcer-inguinal adenopathy disease (GUD) and heterosexual HIV infection. This study aimed to prospectively define the etiology of GUD in patients at the Princess Margaret Hospital during outbreaks of crack cocaine use GUD and HIV infection in the Bahamas. In Nassau 47 consecutive patients with GUD underwent serologic testing for syphilis and for infections with HIV simplex virus type 2 (HSV-2) and Chlamydia trachomatis. Genital ulcer specimens were tested by culture and/or polymerase chain reaction (PCR) assay for Hemophilus ducreyi; by PCR and/or antigen assay for HSV; and by PCR for C trachomatis. Lymph node aspirates were tested by PCR for C trachomatis and H ducreyi. 20 patients (43%) had HIV infection; 8 had lymphogranuloma venereum (LGV) confirmed by PCR detection of C trachomatis sequences consistent with the L2 serovar; and 9 others had possible LGV on the basis of serum microimmunoflourescent C trachomatis antibody titers >or= 256. Inguinal lymphadenopathy or bubo was present in 15 of 17 patients who thus met the laboratory criteria for definite or possible LGV and in 7 of 30 who did not meet such laboratory criteria (P < 0.001). 13 patients had confirmed genital herpes seven had confirmed chancroid and four had probable or possible primary syphilis. The epidemic in the Bahamas of crack use heterosexual HIV infection and GUD apparently included epidemic transmission of LGV. (authors)

Haemophilus ducreyi causes chancroid, a genital ulcer disease (GUD) that is common in many developing countries ([13][1], [14][2], [26][3], [68][4], [80][5], [103][6]). UNAIDS and the World Health Organization estimate that the annual global incidence of chancroid is approximately 6 million cases ([

Conventionally, drugs are discovered by testing chemically synthesized compounds against a battery of in vivo biological screens. Information technology and Omic science enabled us for high throughput screening of compound libraries against biological targets and hits are then tested for efficacy in cells or animals. Chancroid, caused by Haemophilus ducreyi is a public health problem and has been recognized as a cofactor for Human Immunodeficiency Virus (HIV) transmission. It facilitates HIV transmission by providing an accessible portal entry, promoting viral shedding, and recruiting macrophages as well as CD4 cells to the skin. So, there is a requirement to develop an efficient drug to combat Chancroid that can also diminish HIV infection. In-silico screening of potential inhibitors against the target may facilitate in detection of the novel lead compounds for developing an effective chemo preventive strategy against Haemophilus ducreyi. The present study has investigated the effects of approximately 1100 natural compounds that inhibit three vital enzymes viz. Phosphoenolpyruvate phosphotransferase, Acetyl-coenzyme A carboxylase and Fructose 1, 6-bisphosphatase of Haemophilus ducreyi in reference to a commercial drug Rifabutin. Results reveal that the lead compound uses less energy to bind to target. The lead compound parillin has also been predicted as less immunogenic in comparison to Rifabutin. Further, better molecular dynamics, pharmacokinetics, pharmacodynamics and ADME-T properties establish it as an efficient chancroid preventer.

1 Mitja O, Lukehart SA, Pokowas G, et al. Haemophilus ducreyi as a cause of skin ulcers in children from a yaws-endemic area of Papua New Guinea: a prospective cohort study. Lancet Glob Health 2014; 2: e235–41. 2 Liang C, Chu Y, Cheng S, et al. Multiplex loop-mediated isothermal amplifi cation detection by sequence-based barcodes coupled with nicking endonuclease-mediated pyrosequencing. Anal Chem 2012; 84: 3758–63. 3 Ablordey A, Amissah DA, Aboagye IF, et al. Detection of Mycobacterium ulcerans by the loop mediated isothermal amplifi cation method. PLoS Negl Trop Dis 2012; 6: e1590. 4 Ussher JE, Wilson E, Campanella S, Taylor SL, Roberts SA. Haemophilus ducreyi causing chronic skin ulceration in children visiting Samoa. Clin Infect Dis 2007; 44: e85–87. 5 Thornton AC, O’Mara EM Jr, Sorensen SJ, et al. Prevention of experimental Haemophilus ducreyi infection: a randomized, controlled clinical trial. J Infect Dis 1998; 177: 1608–13. 6 Roberts SA, Taylor SL. Haemophilus ducreyi: a newly recognised cause of chronic skin ulceration. Lancet Glob Health 2014; 2: e187–88. 7 Ayove T, Houinei W, Wangnapi R, et al. Sensitivity and specifi city of a rapid point-ofcare test for active yaws: a comparative study. Lancet Glob Health 2014; published online May 30. http://dx.doi.org/10.1016/S2214109X(14)70231-1 Rapid molecular diagnosis of chronic skin ulcers

Haemophilus ducreyi causes chancroid, a sexually transmitted infection. A primary means by which this pathogen causes disease involves eluding phagocytosis; however, the molecular basis for this escape mechanism has been poorly understood. Here, we report that the LspA virulence factors of H. ducreyi inhibit phagocytosis by stimulating the catalytic activity of C-terminal Src kinase (Csk), which itself inhibits Src family protein tyrosine kinases (SFKs) that promote phagocytosis. Inhibitory activity could be localized to a 37-kDa domain (designated YL2) of the 456-kDa LspA1 protein. The YL2 domain impaired ingestion of IgG-opsonized targets and decreased levels of active SFKs when expressed in mammalian cells. YL2 contains tyrosine residues in two EPIYG motifs that are phosphorylated in mammalian cells. These tyrosine residues were essential for YL2-based inhibition of phagocytosis. Csk was identified as the predominant mammalian protein interacting with YL2, and a dominant-negative Csk rescued phagocytosis in the presence of YL2. Purified Csk phosphorylated the tyrosines in the YL2 EPIYG motifs. Phosphorylated YL2 increased Csk catalytic activity, resulting in positive feedback, such that YL2 can be phosphorylated by the same kinase that it activates. Finally, we found that the Helicobacter pylori CagA protein also inhibited phagocytosis in a Csk-dependent manner, raising the possibility that this may be a general mechanism among diverse bacteria. Harnessing Csk to subvert the Fcγ receptor (FcγR)-mediated phagocytic pathway represents a new bacterial mechanism for circumventing a crucial component of the innate immune response and may potentially affect other SFK-involved cellular pathways., IMPORTANCE Phagocytosis is a critical component of the immune system that enables pathogens to be contained and cleared. A number of bacterial pathogens have developed specific strategies to either physically evade phagocytosis or block the intracellular signaling required for phagocytic activity. Haemophilus ducreyi, a sexually transmitted pathogen, secretes a 4,153-amino-acid (aa) protein (LspA1) that effectively inhibits FcγR-mediated phagocytic activity. In this study, we show that a 294-aa domain within this bacterial protein binds to C-terminal Src kinase (Csk) and stimulates its catalytic activity, resulting in a significant attenuation of Src kinase activity and consequent inhibition of phagocytosis. The ability to inhibit phagocytosis via Csk is not unique to H. ducreyi, because we found that the Helicobacter pylori CagA protein also inhibits phagocytosis in a Csk-dependent manner. Harnessing Csk to subvert the FcγR-mediated phagocytic pathway represents a new bacterial effector mechanism for circumventing the innate immune response.

To adapt to stresses encountered in stationary phase, Gram-negative bacteria utilize the alternative sigma factor RpoS. However, some species lack RpoS; thus, it is unclear how stationary-phase adaptation is regulated in these organisms. Here we defined the growth-phase-dependent transcriptomes of Haemophilus ducreyi, which lacks an RpoS homolog. Compared to mid-log-phase organisms, cells harvested from the stationary phase upregulated genes encoding several virulence determinants and a homolog of hfq. Insertional inactivation of hfq altered the expression of ~16% of the H. ducreyi genes. Importantly, there were a significant overlap and an inverse correlation in the transcript levels of genes differentially expressed in the hfq inactivation mutant relative to its parent and the genes differentially expressed in stationary phase relative to mid-log phase in the parent. Inactivation of hfq downregulated genes in the flp-tad and lspB-lspA2 operons, which encode several virulence determinants. To comply with FDA guidelines for human inoculation experiments, an unmarked hfq deletion mutant was constructed and was fully attenuated for virulence in humans. Inactivation or deletion of hfq downregulated Flp1 and impaired the ability of H. ducreyi to form microcolonies, downregulated DsrA and rendered H. ducreyi serum susceptible, and downregulated LspB and LspA2, which allow H. ducreyi to resist phagocytosis. We propose that, in the absence of an RpoS homolog, Hfq serves as a major contributor of H. ducreyi stationary-phase and virulence gene regulation. The contribution of Hfq to stationary-phase gene regulation may have broad implications for other organisms that lack an RpoS homolog., IMPORTANCE Pathogenic bacteria encounter a wide range of stresses in their hosts, including nutrient limitation; the ability to sense and respond to such stresses is crucial for bacterial pathogens to successfully establish an infection. Gram-negative bacteria frequently utilize the alternative sigma factor RpoS to adapt to stresses and stationary phase. However, homologs of RpoS are absent in some bacterial pathogens, including Haemophilus ducreyi, which causes chancroid and facilitates the acquisition and transmission of HIV-1. Here, we provide evidence that, in the absence of an RpoS homolog, Hfq serves as a major contributor of stationary-phase gene regulation and that Hfq is required for H. ducreyi to infect humans. To our knowledge, this is the first study describing Hfq as a major contributor of stationary-phase gene regulation in bacteria and the requirement of Hfq for the virulence of a bacterial pathogen in humans.

Intracellular acting protein exotoxins produced by bacteria and plants are important molecular determinants that drive numerous human diseases. A subset of these toxins, the cytolethal distending toxins (CDTs), are encoded by several Gram-negative pathogens and have been proposed to enhance virulence by allowing evasion of the immune system. CDTs are trafficked in a retrograde manner from the cell surface through the Golgi apparatus and into the endoplasmic reticulum (ER) before ultimately reaching the host cell nucleus. However, the mechanism by which CDTs exit the ER is not known. Here we show that three central components of the host ER associated degradation (ERAD) machinery, Derlin-2 (Derl2), the E3 ubiquitin-protein ligase Hrd1, and the AAA ATPase p97, are required for intoxication by some CDTs. Complementation of Derl2-deficient cells with Derl2:Derl1 chimeras identified two previously uncharacterized functional domains in Derl2, the N-terminal 88 amino acids and the second ER-luminal loop, as required for intoxication by the CDT encoded by Haemophilus ducreyi (Hd-CDT). In contrast, two motifs required for Derlin-dependent retrotranslocation of ERAD substrates, a conserved WR motif and an SHP box that mediates interaction with the AAA ATPase p97, were found to be dispensable for Hd-CDT intoxication. Interestingly, this previously undescribed mechanism is shared with the plant toxin ricin. These data reveal a requirement for multiple components of the ERAD pathway for CDT intoxication and provide insight into a Derl2-dependent pathway exploited by retrograde trafficking toxins., Author Summary Cytolethal distending toxins (CDTs) are produced by several bacterial pathogens and increase the ability of these bacteria to cause disease. After being taken up by host cells, CDTs are trafficked to the endoplasmic reticulum (ER) where they must translocate across the ER membrane to gain access to their intracellular target; however, this translocation process is poorly understood for CDTs. Here we provide evidence that CDTs require components of the ER-associated degradation (ERAD) pathway, a normal cellular process utilized to translocate terminally misfolded ER lumenal and membrane proteins across the ER membrane for degradation in the cytosol. Deletion of a key member of this pathway, Derl2, makes cells resistant to multiple CDTs. Interestingly, two domains within Derl2 which are required for ERAD of misfolded proteins are dispensable for intoxication by CDT. Further, we report two previously uncharacterized domains within Derl2 that are each required for intoxication. Consistent with a role of Derl2, abrogation of two other members of the ERAD pathway, Hrd1 and p97, results in retention of CDT in the ER and resistance to intoxication. Taken together, these data provide novel insight into how CDTs exit the ER and therefore gain access to their cellular targets.

Haemophilus ducreyiis the etiologic agent of chancroid, a sexually transmitted genital ulcer disease that facilitates the transmission of human immunodeficiency virus. In the human model of infection, the histopathology of infected sites in part resembles a delayed-type hypersensitivity (DTH) response. In this study, T cells were isolated from skin biopsy specimens obtained from 24 subjects who were infected for 7 to 14 days. One clone and 12 lines that responded toH. ducreyiantigens were obtained from 12 of the subjects. Fluorescence-activated cell sorter analysis showed that the antigen-responsive lines and clone were predominantly CD3+and CD4+. The lines and clone responded toH. ducreyiantigen in a dose-dependent manner and produced gamma interferon (IFN-γ) alone or IFN-γ and interleukin-10 (IL-10) but no IL-4 or IL-5 in response toH. ducreyi. Proliferation of T cells was dependent on the presence of autologous antigen-presenting cells. The lines showed little response to antigens prepared from other members of thePasteurellaceaeand responded to different fractions ofH. ducreyiseparated by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We conclude that T cells that recognizeH. ducreyiantigens are recruited to sites experimentally infected with the organism. The lack of cross-reactivity to thePasteurellaceaeand the response of the lines to different antigen fractions suggest that subjects are sensitized toH. ducreyiduring the course of infection.

A sensitive and specific PCR method to detect Treponema pallidum in clinical specimens was developed. PCR primers were designed based on two unique features of the DNA polymerase I gene ( polA ). The first distinctive characteristic is that the region codes for a high cysteine content and has low homology with similar regions of DNA polymerase I gene from known microorganisms. The second unique feature is the presence of four insertions in the gene. PCR tests using primers designed on the basis these regions reacted with various pathogenic T. pallidum subspecies but did not react with nonpathogenic treponemal species or other spirochetes. An additional 59 species of bacteria and viruses, including those that cause genital ulcers, tested negative. This PCR method is extremely robust and sensitive. The detection limit is about 10 to 25 organisms when analyzed on gel. However, the analytic sensitivity can be increased by at least 1 log, to a detection limit of a single organism, when the ABI 310 Prism Genetic Analyzer is used to detect fluorescence-labeled amplicons. We further used this test in a clinical setting and compared the results with results from a previously reported multiplex-PCR test (for T. pallidum, Haemophilus ducreyi , and herpes simplex virus). We tested 112 genital ulcer specimens by the polA PCR, obtaining a sensitivity of 95.8% and a specificity of 95.7%. These results suggest that the polA PCR is applicable as a routine clinical diagnostic test for syphilis.