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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.

Haemophilus ducreyi colocalizes with polymorphonuclear leukocytes and macrophages and evades phagocytosis during experimental infection of human volunteers. H. ducreyi contains two genes, lspA1 and lspA2, which encode predicted proteins of 456 and 543 kDa, respectively. Compared to its wild-type parent, an lspA1 lspA2 double mutant does not inhibit phagocytosis by macrophage and myelocytic cell lines in vitro and is attenuated in an experimental rabbit model of chancroid. To test whether expression of LspA1 and LspA2 was necessary for virulence in humans, six volunteers were experimentally infected. Each volunteer was inoculated with three doses (ranging from 85 to 112 CFU) of the parent (35000HP) in one arm and three doses (ranging from 60 to 822 CFU) of the mutant (35000HP Omega 12) in the other arm. The papule formation rates were 88% (95% confidence interval [95% CI], 76.8 to 99.9%) at 18 parent sites and 72% (95% CI, 44.4 to 99.9%) at 18 mutant sites (P = 0.19). However, papules were significantly smaller at mutant sites (mean size, 24.8 mm(2)) than at parent sites (mean size, 39.1 mm(2)) 24 h after inoculation (P = 0.0002). The pustule formation rates were 44% (95% CI, 5.8 to 77.6%) at parent sites and 0% (95% CI, 0 to 39.4%) at mutant sites (P = 0.009). With the caveat that biosafety regulations preclude testing of a complemented mutant in human subjects, these results indicate that expression of LspA1 and LspA2 facilitates the ability of H. ducreyi to initiate disease and to progress to pustule formation in humans.

An intact Haemophilus ducreyi flp operon is essential for microcolony formation in vitro. tadA is the 9th of 15 genes in the operon and has homology to NTPases of type IV secretion systems. Fifteen human volunteers were experimentally infected with both H. ducreyi 35000HP and the tadA mutant, 35000HP.400. Papules developed at similar rates at sites inoculated with the mutant and parent, while pustules formed at 36.4% of parent sites and at 0% of mutant sites (P = 0.001). Compared to 35000HP, 35000HP.400 had only a modest but significant reduction in lesion scores in the temperature-dependent rabbit model of chancroid. These data suggest that proteins secreted by the flp locus are required for full expression of virulence by H. ducreyi in humans but have less of a role in virulence in an animal model of infection.

The cytolethal distending toxin of Haemophilus ducreyi (HdCDT) is a three-component toxin that induces the arrest of the mammalian cell cycle in the G2 phase. All of the individual gene products, CdtA, CdtB and CdtC, are required for toxic activity on cultured mammalian cells. The CdtB component alone exerts nuclease activity. The individual HdCDT components were purified by affinity chromatography or ion-exchange chromatography followed by gel-filtration. HdCDT was reconstituted and purified by the immobilization of a GST-CdtB fusion on a GSTrap column and the subsequent addition of cell sonicates from Escherichia coli recombinants that produced CdtA and CdtC. The purified HdCDT preparation contained all three CDT proteins, as detected by immuno-blotting, and had high cytotoxic activity (10(6)CPU/ml). Immunization of rabbits with the HdCDT complex and with the individual CdtA, CdtB and CdtC proteins elicited high titres of antibodies, as detected by ELISA. All of the immune sera had toxin-neutralizing activities. The pathological effects of the HdCDT complex were investigated in rabbits, since the proliferation of two rabbit cell lines, SIRC and RK-13, was inhibited by HdCDT. Intradermal injection of HdCDT (1, 10, 50 and 100microg protein) into naive rabbits resulted in dose-dependent skin reactions (erythema) about 24h after injection. Similar effects were not observed when the individual HdCDT proteins were injected. HdCDT injection into immune rabbits resulted in dose-dependent skin responses that were characterized by both erythema and oedema. Histological evaluation of the 24-h lesions in naive rabbits that were injected with HdCDT, revealed moderate levels of inflammatory cells, which were mainly granulocytes and macrophages, and dilatation of blood vessels. The skin reactions in HdCDT-injected immunized rabbits showed pronounced vascular changes and extensive infiltration of inflammatory cells, including eosinophils. All of the pathological changes healed after 3 days. In conclusion, purified HdCDT holotoxin is a complex of all three CDT proteins and all three components induce neutralizing antibodies when injected in rabbits. HdCDT causes dose-dependent pathologic skin reactions in both naive and immune rabbits, which is characterized by increased inflammatory responsiveness after each immunization.

Haemophilus ducreyi causes the sexually transmitted disease chancroid, which facilitates the transmission of HIV infection. This review focuses on recent advances in the epidemiology, diagnosis, treatment and pathogenesis of this disease.

The lipooligosaccharide (LOS) of Haemophilus ducreyi contains a major glycoform that is immunochemically identical to paragloboside, a glycosphingolipid precursor of major human blood group antigens. We recently identified the gene responsible for the glucosyltransferase activity and constructed an isogenic mutant (35000glu-) deficient in this activity. 35000glu- makes an LOS that consists only of the heptose trisaccharide core and 2-keto-deoxyoctulosonic acid (KDO). For this study, the mutant was reconstructed in the 35000HP (human passaged [HP]) background. Five human subjects were inoculated with 35000HP and 35000HPglu- in a dose-response trial. The pustule formation rates were 40% (95% confidence interval [CI], 13.7 to 72.6%) at 10 sites for 35000HP and 46.7% (95% CI, 24.8 to 69.9%) at 15 sites for 35000HPglu-. The histopathology and recovery rates of H. ducreyi from surface cultures and biopsies obtained from mutant and parent sites were similar. These results indicate that the expression of glycoforms with sugar moieties extending beyond the heptose trisaccharide core is not required for pustule formation by H. ducreyi in humans.

Background and Objectives: To study Haemophilus ducreyi pathogenesis, the authors developed an experimental model of infection in human volunteers. The authors analyze their cumulative experience with strain 35000 in the model and calculate the papule and pustule formation rates for estimated delivered doses (EDDs) ranging from 1 cfu to 100 cfu., Study Design: Sixty-five volunteers were included in the analysis. A total of 139 sites were available for calculation of the papule formation rate, and 117 sites were available for calculation of the pustule formation rates., Results: The effect of EDDs and probabilities of papule formation and the pustule formation were dose-dependent. Increasing the EDD resulted in a higher probability of papule and pustule formation., Conclusion: H ducreyi is highly infectious for humans. Inoculation of an EDD of 1 cfu causes a papule formation rate of 50%. Pustule formation rates are approximately 50% for 27 cfu and 90% for 100 cfu.

The lipooligosaccharide (LOS) of Haemophilus ducreyi, the etiologic agent of chancroid, chemically and immunologically resembles human glycosphingolipid antigens. To test whether LOS that contains paragloboside-like structures was required for pustule formation, an isogenic mutant (35000HP-RSM2) was constructed in losB, which encodes D-glycero-D-manno-heptosyltransferase. 35000HP-RSM2 produces a truncated LOS whose major glycoform terminates in a single glucose attached to a heptose trisaccharide core and 2-keto-3-deoxyoctulosonic acid. Five human subjects were inoculated with 35000HP and 35000HP-RSM2 in a dose-response trial. For estimated delivered doses (EDDs) of >/=25 CFU, the pustule formation rates were 80% for 35000HP and 58% for 35000HP-RSM2. Preliminary data indicated that a previously described Tn916 losB mutant made a minor glycoform that does not require DD-heptose to form the terminal N-acetyllactosamine. If 35000HP-RSM2 made this glycoform, then 35000HP-RSM2 could theoretically make a sialylated glycoform. To test whether sialylated LOS was required for pustule formation, a second trial comparing an isogenic sialyltransferase mutant (35000HP-RSM203) to 35000HP was performed in five additional subjects. For EDDs of >/=25 CFU, the pustule formation rates were 30% for both 35000HP and 35000HP-RSM203. The histopathology and recovery rates of H. ducreyi from surface cultures and biopsies obtained from mutant and parent sites in both trials were similar. These results indicate that neither the expression of a major glycoform resembling paragloboside nor sialylated LOS is required for pustule formation by H. ducreyi in humans.

Human volunteers were challenged with Haemophilus ducreyi. Twenty subjects were inoculated with 2 doses (approximately 30 cfu) of live and 1 dose of heat-killed bacteria at 3 sites on the arm. Eight subjects were assigned to biopsy 1 or 4 days after inoculation, and 12 were biopsied after they developed a painful pustular lesion or were followed until disease resolved. Papules developed at 95% of 40 sites infected with live bacteria (95% confidence interval [CI], 83. 1%-99.4%). In 24 sites followed to end point, 27% of the papules resolved, 69% (95% CI, 47.1%-86.6%) evolved into pustules, and 4% remained at the papular stage. Recovery rates of H. ducreyi from surface cultures ranged from 13% to 41%. H. ducreyi was recovered from biopsies of 12 of 15 pustules and 1 of 7 papules, suggesting that H. ducreyi replicates between the papular and pustular stages of disease.

Absent for several decades, the chancroid reappeared in Algeria in 1988. In the unique department of Dermatology and Venereology of the University Hospital of the country of Tlemcen (more than 700,000 inhabitants), we wanted to know the state of this STD seven years after the report of the first cases. The file of the consulting patients were examined. We looked for the principal characteristics of this STD: age, sex, incubation period, place infection contact, type of relation, clinical presentation, evolution without and with treatment, other associated STD (syphilis, HIV). From August 1988 (1st case) to December 1995, 144 cases of chancroid were collected = 1988: 6, 1989: 5, 1990: 7, 1991: 18, 1992: 11, 1993: 33, 1994: 48, 1995: 16. The presentation is quite stereotyped; it concerns males only, singles in must cases, having had sexual relations with prostitutes. The incubation period is short (less than 10 days), the characteristic ulceration presents, very often, some adenopathies. The treatment by cotrimoxazole is efficient. They are no concomitant syphilis or HIV infection. The chancroid is the first cause of genital ulceration in the world. Since 1991, it is the principal STD in our department. It spreads within a male population, young singles associated with prostitutes. It is well installed in Algeria, and its role, although minor, in the transmission of the HIV infection, should not be neglected.

One-hundred thirteen men (mean age, 23 years) who presented with inguinal buboes to a government-operated hospital for sexually transmitted diseases (STDs) in Bangkok were studied between February 1987 and February 1989. The median duration of preceding symptoms was 7 days (range, 1-62 days). The majority of patients (74; 65%) had received treatment previously; 31 (27%) were febrile, 13 (12%) had extrainguinal lymphadenopathy, and 31 (27%) had concurrent active genital ulcers. There was no history of genital ulceration in 66 (58%) of the patients. Pus was obtained from 51 of the 110 buboes aspirated for culture; 21 (41%) of these cultures yielded Haemophilus ducreyi, and 2 (3.9%) were positive for Chlamydia trachomatis on immunofluorescence microscopy. Saline (1 mL) was injected and reaspirated from the buboes of 35 of the other 59 patients; 3 buboes yielded H. ducreyi and 9 were positive for C. trachomatis. All cultures for other aerobic and anaerobic bacteria and viruses in intact buboes were negative. Syphilis serology was positive in only one case. Patients attending STD clinics in this region who have large, fluctuant, edematous inguinal buboes containing pus should receive presumptive treatment for chancroid. If there is no pus, then the bubo is more likely to be caused by lymphogranuloma venereum.

Haemophilus ducreyi is a strict human pathogen that causes sexually transmitted genital ulcer disease. We infected domestic swine with H. ducreyi 35000, resulting in the development of cutaneous ulcers histologically resembling human chancroid lesions. Intraepidermal lesions progressed from pustules to ulcers containing polymorphonuclear leukocytes and were accompanied by a dermal inflammatory infiltrate containing T cells and macrophages. H. ducreyi was recovered from lesions up to 17 days after inoculation, and pigs did not develop immunity to reinfection with the challenge strain. Features of the model include inoculation through abrasions in the epidermis, ambient housing temperatures for infected pigs, the ability to deliver multiple different inocula to a single host, and the availability of monoclonal antibodies against porcine immune cells permitting immunohistochemical characterization of the host immune response to H. ducreyi infection.

Adult pigtailed macaques (Macaca nemestrina) were evaluated for their usefulness as a primate model for chancroid. To initiate infection, 10(7)-10(8) cfu of Haemophilus ducreyi were inoculated into the foreskins of 5 adult males and into the vaginal labia of 4 adult females. Lesions developed in the male macaques that were similar in appearance, histopathologic changes, and progression to those of human disease, including the development of ulcers 6-12 days after infection. In addition, H. ducreyi could be recovered from the lesions up to 20 days after inoculation, humoral antibodies were induced beginning 1 week after inoculation, and inguinal lymphadenopathy was noted in 4 of the 5 males. None of the 4 female macaques inoculated with the same preparation of live H. ducreyi developed comparable lesions. Thus, experimental chancroid in adult male macaques closely resembles human disease and should be useful for future studies of the pathogenesis of chancroid.

Four subjects were experimentally infected with Haemophilus ducreyi. Lesions developed only at sites where live bacteria were inoculated on abraded skin. No subject developed fever, lymphadenopathy, or disseminated infection during a 3-day observation period. Two subjects who were rechallenged 2 months after initial infection also developed lesions. The amount of H. ducreyi recovered from 10 of 12 biopsies that were semiquantitatively cultured varied widely. Similar histologic features were present in initial and second infections. The epidermis contained pustules; the dermis contained an infiltrate of T cells and macrophages and reactive endothelial cells. Keratinocytes and T cells expressed HLA-DR, consistent with a delayed-type hypersensitivity response. The subjects did not mount humoral responses to bacterial proteins and to lipooligosaccharides after primary and secondary challenges. Thus, human experimental infection with H. ducreyi is well tolerated and safe. Recruitment of T cells and macrophages into chancroid lesions may partially explain the association between chancroid and human immunodeficiency virus transmission.

Restriction fragment length polymorphism (RFLP) and plasmid analyses were used to evaluate an outbreak of Haemophilus ducreyi in San Francisco. Fifty-four cases of culture-confirmed chancroid occurred between May 1989 and May 1991. Of these, 46 (96%) were in men and 35 (65%) were in blacks; the median age of patients was 34 years. Among the 32 isolates submitted for RFLP and plasmid analyses, six different HindIII RFLP patterns were identified. Two RFLP types were found in patients who had recently traveled to Los Angeles, Korea, or El Salvador. Four RFLP types appeared to be acquired locally and were more common among blacks (P = .002), in patients with a history of a sexually transmitted disease (P = .01), and in those who used drugs or exchanged drugs or money for sex (P = .08). The use of RFLP analysis confirmed that this outbreak was associated with multiple strains of H. ducreyi and allowed for the identification of risk factors for locally acquired chancroid.

Haemophilus ducreyi (H. ducreyi) strains, representing both reference strains and low-passage isolates, were investigated in terms of surface structures and enzymatic equipment. The interaction of these factors with host tissue was analysed using new in vitro- and in vivo-models. By electron microscopy studies there was no evidence of an extracellular capsule or surface appendages such as pili or flagella. Interaction of all isolates tested with the lectin Phaseolus vulgaris suggests N-acetyl-D-glucosamine units as common structural features of H. ducreyi cell envelope polysaccharide. In attachment to epithelial cells more than one hemagglutinin might be implicated as different haemagglutination patterns could be observed whereby the activity was not heat-labile, but was abolished by formaldehyde. Hydrophobic interactions might be of importance as well as strains showed a wide range of reactions from hydrophobic to hydrophilic, low hydrophobicity being more marked with the older strains. No elaboration of degradative enzymes based on the measurement of enzymatic activity using insoluble dye-protein complexes could be detected in case of H. ducreyi, using Azocoll and Remazol Brilliantblue hide powder for detection of proteolytic activity and elastinorcein for detection of elastase activity. In vitro studies using human keratinocytes and Vero cells did not show any morphological changes when incubated with H. ducreyi culture filtrates. In vivo studies with a new mouse model for H. ducreyi infection could confirm the results of the in vitro studies. Mere contact to undamaged skin both of whole cell organisms, live or heat-killed, and of culture filtrates did not lead to any reaction or even damage of mouse skin. However, when the outer epidermal layer was overcome by intradermal injection of shaved mice ulcers developed. Tissue necrosis production was not bound to live organisms as dead ones showed the same effect. There is great evidence that this tissue necrosis is associated with H. ducreyi lipopolysaccharide (LPS) because intradermal injection of purified H. ducreyi LPS lead to the same reaction pattern. For the first time a cell mediated immune response could be demonstrated in case of H. ducreyi infection as different antigen preparations of H. ducreyi isolates induced proliferation of lymphocytes isolated from healthy unexposed individuals and from a chancroid-sensitized male. In the latter case measured cell responses were much stronger. The dose-dependent phenomenon was associated with interleukin-2 production. In summary, H. ducreyi isolates do not exhibit cytotoxic effects on the epithelial cells of the skin.(ABSTRACT TRUNCATED AT 400 WORDS)

This article summarizes the major sexually transmitted diseases with an emphasis on diagnosis, therapy, and follow-up. Topics included are syphilis, gonorrhea, herpes genitalis, nongonococcal urethritis, lymphogranuloma venereum, granuloma inguinale, chancroid, condyloma acuminatum, molluscum contagiosum, and venereally transmitted gastrointestinal disease.

The treatment of non-complicated or complicated (by a bubo) chancroid with 1 single i.m. injection of 250 mg ceftriaxone gave excellent results. Treatment is simple and economical. This is particularly profitable in countries where chancroid is endemic.