Syphilis: using modern approaches to understand an old disease

Ocular vs neurosyphilis. are they the same? A guide to investigation and management

This article reviews key concepts in the epidemiology, clinical features, diagnosis and management of ocular syphilis. It is not a systematic review or meta-analysis, but highlights the critical clinical features and investigations in patients with ocular syphilis. It reviews the overlap and interplay between ocular and neuro syphilis and provides practical guidance to diagnose and manage patients with ocular syphilis.

Prevalence and Predictors of Oral Treponema pallidum Detection by Quantitative Polymerase Chain Reaction in Early Syphilis

BACKGROUND

Treponema pallidum prevalence and burden at oral and lesion sites in adults with early syphilis were assessed by quantitative polymerase chain reaction (qPCR). Factors associated with oral shedding were also examined.

METHODS

Pretreatment oral and lesion swabs were collected from adults with early syphilis in a US multicenter syphilis treatment trial. Oral swabs were collected in the presence and absence of oral lesions. Following DNA extraction, qPCR and whole-genome sequencing (WGS) were performed to assess burden and strain variability.

RESULTS

All 32 participants were male, mean age was 35 years, and 90.6% with human immunodeficiency virus (HIV). T. pallidum oral PCR positivity varied by stage: 16.7% primary, 44.4% secondary, and 62.5% in early latent syphilis. Median oral T. pallidum burden was highest in secondary syphilis at 63.2 copies/µL. Lesion PCR positivity was similar in primary (40.0%) and secondary syphilis (38.5%). Age 18-29 years was significantly associated with oral shedding (vs age 40+ years) in adjusted models. WGS identified 2 distinct strains.

CONCLUSIONS

T. pallidum DNA was directly detected at oral and lesion sites in a significant proportion of men with early syphilis. Younger age was associated with oral shedding. Ease of oral specimen collection and increased PCR availability suggest opportunities to improve syphilis diagnostic testing. Clinical Trials Registration. NCT03637660.

2023 Korean sexually transmitted infections guidelines for non-gonococcal bacterial infection (chlamydia, syphilis, etc.) by the Korean Association of Urogenital Tract Infection and Inflammation

Non-gonococcal sexually transmitted infections (STIs) include chlamydia, syphilis, and chancroids. Chlamydia is the most common STI caused by Chlamydia trachomatis and is mainly transmitted through sexual intercourse or vertical transmission at birth. Although symptoms are mostly absent or mild, untreated chlamydial infections in females can lead to pelvic inflammatory disease, chronic pelvic pain, and infertility due to the narrowing of fallopian tubes. Syphilis is caused by Treponema pallidum and is divided into phase I, phase II, latent syphilis, and phase III. The incidence of syphilis, including congenital syphilis, has significantly increased in the United States in recent years. The chronic status of this disease can significantly increase morbidity and potentially affect almost all body organs, which, in rare cases, can lead to death. Additionally, untreated maternal syphilis can lead to fetal death and fatal congenital infections in newborns. Chancroid is an STI caused by Haemophilus ducreyi, and its prevalence is gradually decreasing in Korea and worldwide. The symptoms include shallow genital ulcers with suppurative granulomatous inflammation and tender inguinal lymphadenopathy. Chancroids can be differentiated from syphilitic chancres based on their appearance. In contrast to painless chancres, chancroids are painful. Ureaplasma urealyticum, Ureaplasma parvum, and Mycoplasma hominis are considered symbiotic bacteria. Infections caused by these bacteria are usually not considered STIs and do not require treatment unless they are suspected of being associated with infertility. This article presents the 2023 Korean STI guidelines for non-gonococcal bacterial infections.

Some lesser-known facts on the early history of syphilis in Europe

At the end of the 15th century, an epidemic outbreak occurred in Europe for which the cause was previously unknown. Clinical findings included numerous ulcerations and condylomas as well as disorders of the cardiovascular and neurologic systems. The disease, which had many names at the time and killed about 5 million people, is referred to as syphilis in today's medical terminology. The epidemiology of syphilis is complex and represents an important issue, not only historically but also scientifically, in the development of medicine. Several theories emerged about the origin of this disease, including pre-Columbian and Columbian ones. This contribution aims to present the history of the origin of syphilis, with particular emphasis on the first reports of the disease in Poland.

Dysregulation of circulating T follicular helper cell subsets and their potential role in the pathogenesis of syphilis

Introduction

The role of the host immune response could be critical in the development of Treponema pallidum (Tp) infection in individuals with latent syphilis. This study aims to investigate the alterations in T follicular helper T (Tfh) cell balance among patients with secondary syphilis and latent syphilis.

Methods

30 healthy controls (HCs), 24 secondary syphilis patients and 41 latent syphilis patients were enrolled. The percentages of total Tfh, ICOS+ Tfh, PD-1+ Tfh, resting Tfh, effector Tfh, naïve Tfh, effector memory Tfh, central memory Tfh,Tfh1, Tfh2, and Tfh17 cells in the peripheral blood were all determined by flow cytometry.

Results

The percentage of total Tfh cells was significantly higher in secondary syphilis patients compared to HCs across various subsets, including ICOS+ Tfh, PD-1+ Tfh, resting Tfh, effector Tfh, naïve Tfh, effector memory Tfh, central memory Tfh, Tfh1, Tfh2, and Tfh17 cells. However, only the percentages of ICOS+ Tfh and effector memory Tfh cells showed significant increases in secondary syphilis patients and decreases in latent syphilis patients. Furthermore, the PD-1+ Tfh cells, central memory Tfh cells, and Tfh2 cells showed significant increases in latent syphilis patients, whereas naïve Tfh cells and Tfh1 cells exhibited significant decreases in secondary syphilis patients when compared to the HCs. However, no significant change was found in resting Tfh and effector Tfh in HCs and secondary syphilis patients or latent syphilis patients.

Discussion

Dysregulated ICOS+ Tfh or effector memory Tfh cells may play an important role in immune evasion in latent syphilis patients.

Good performance of syphilis rapid diagnostic test kits among young key populations in Thailand

BACKGROUND

The prevalence of syphilis is increasing among adolescents and young adults (AYAs) globally. Use of syphilis rapid diagnostic treponemal tests (RDTs) may improve test coverage and same-day treatment. This study aims to determine sensitivity and specificity of two syphilis RDTs.

METHODS

A cross-sectional study was conducted in men who have sex with men and transgender women aged 15-24 years attending a sexual health clinic in Bangkok. Syphilis RDTs used were Determine Syphilis TP and Bioline Syphilis 3.0, using whole blood from finger pricks and venipuncture. Treponemal pallidum electrochemiluminescence assay was used as standard reference.

RESULTS

From February to July 2022, 200 AYAs with a mean age 21.1 (SD2.1) years were enrolled, including 50 (25.0%) living with HIV. Prevalence of syphilis was 10.5% (95%CI 6.6-15.6), which was higher among AYAs living with HIV (22.0%) compared with AYAs unaffected by HIV (6.7%). Sensitivities of Determine Syphilis TP and Bioline Syphilis 3.0 were 85.7% (95%CI 63.7-97.0) and 66.7% (95%CI 43.0-85.4), respectively. Specificity of both RDTs was 100% (95%CI 98.0-100.0). Performance of RDTs was similar for both specimens.

CONCLUSIONS

Syphilis RDTs have high sensitivity and specificity in diagnosing syphilis. It should be considered for use in sexual health clinics with high syphilis prevalence to initiate treatment promptly.

Syphilis

Syphilis is a sexually and vertically transmitted bacterial infection caused by the bacterium Treponema pallidum. Its prevalence is high in low-income and middle-income countries, and its incidence has increased in high-income countries in the last few decades among men who have sex with men. Syphilis is a major cause of adverse pregnancy outcomes in low-income and middle-income countries. Clinical features include a primary chancre at the point of inoculation, followed weeks later by the rash of secondary syphilis, a latent period, and in some cases, involvement of the eyes, CNS, and cardiovascular systems. It is diagnosed serologically. A single intramuscular dose of long-acting benzathine penicillin is recommended for people who have had syphilis for less than 1 year and longer courses for people with late latent syphilis. Control strategies include screening and treatment of all pregnant women, and targeted interventions for groups at high risk. Vaccine development, research on antibiotic prophylaxis, and digital messaging as prevention strategies are ongoing.

Syphilis vaccine: challenges, controversies and opportunities

Syphilis is a sexually or vertically (mother to fetus) transmitted disease caused by the infection of Treponema pallidum subspecie pallidum (TPA). The incidence of syphilis has increased over the past years despite the fact that this bacterium is an obligate human pathogen, the infection route is well known, and the disease can be successfully treated with penicillin. As complementary measures to preventive campaigns and early treatment of infected individuals, development of a syphilis vaccine may be crucial for controlling disease spread and/or severity, particularly in countries where the effectiveness of the aforementioned measures is limited. In the last century, several vaccine prototypes have been tested in preclinical studies, mainly in rabbits. While none of them provided protection against infection, some prototypes prevented bacteria from disseminating to distal organs, attenuated lesion development, and accelerated their healing. In spite of these promising results, there is still some controversy regarding the identification of vaccine candidates and the characteristics of a syphilis-protective immune response. In this review, we describe what is known about TPA immune response, and the main mechanisms used by this pathogen to evade it. Moreover, we emphasize the importance of integrating this knowledge, in conjunction with the characterization of outer membrane proteins (OMPs), to expedite the development of a syphilis vaccine that can protect against TPA infection.

Secondary Syphilis Presentation and Urticarial Eruption After Moderna COVID-19 Vaccination

The diversity of the cutaneous manifestations of syphilis and the ability of the spirochete to evade diagnosis have been well documented by medical literature. However, what triggers the onset of secondary syphilis is not yet clear because of difficulties studying the bacterium. Our case describes the onset of a heterogeneous rash (or coexisting rashes) that presented the day after vaccination with the Moderna mRNA-1273 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. The potential etiologies of the patient's rash: A vaccine reaction, reactivation of chronic spontaneous urticaria, or a physical sign of syphilis itself are then reviewed. The potential for the Moderna coronavirus disease 2019 (COVID-19) vaccine to be the catalyst of this patient's cutaneous manifestations of his immune system responses is also hypothesized.

Cervical Syphilitic Lymphadenitis in a 29-Year-Old Female: A Case Report

Cervical lymphadenopathy is a common condition characterized by the enlargement of lymph nodes. It can have various causes, including infections, inflammatory conditions, and neoplastic processes. Syphilis, a sexually transmitted disease that progresses through multiple stages, can also be a rare cause of cervical lymphadenopathy, particularly in HIV-positive individuals. In this case report, we describe a patient presenting with throat pain, systemic symptoms, and cervical lymphadenopathy, initially clinically suggestive of lymphoma but ultimately determined to be caused by syphilis of unknown duration. This case highlights the importance of considering syphilis in the differential diagnosis of cervical lymphadenitis, particularly in patients with risk factors, such as intravenous drug use and HIV infection, and the need for a thorough evaluation of the patient's social and medical histories to diagnose and treat the condition accurately.

Malaria therapy for general paralysis of the insane at the Sunbury Hospital for the Insane in Australia, 1925-6

This paper, drawing on the published medical literature and unpublished medical record archives, provides an in-depth account of the introduction of malaria therapy for general paralysis of the insane into Australia in 1925-6, at Victoria's Sunbury Hospital for the Insane. This study reveals a complex and ambiguous picture of the practice and therapeutic impact of malaria therapy in this local setting. This research highlights a number of factors which may have contributed to some physicians overestimating malaria therapy's effectiveness. It also shows that other physicians of the era held a more sceptical attitude towards malaria therapy. Finally, this paper discusses the relevance of this history to contemporary psychiatry.

HIV is still a major public health problem among pregnant women attending ANC in Referral Hospitals of the Amhara Regional State, Ethiopia: a cross sectional study

BACKGROUND

The burden of HIV is disproportionately higher among women of reproductive age contributing more than half of the global share. The situation in Ethiopia is not exceptional. The present study was done to determine the proportion of HIV among pregnant women in Amhara Regional State, Ethiopia.

METHOD

Institutions-based cross-sectional study was conducted from October 2020 to December 2020. Systematic random sampling technique was used to select 538 study participants from pregnant women who had ANC follow-up in Referral Hospitals of the Amhara Regional State. Data on socio-demographic, clinical, obstetric, behavioral as well as psychosocial characteristics were gathered using an interviewer administered structured and standardized instruments. The data was entered into Epi-Data Manager V4.6.0.0 and exported to STATA version 14 for data analyses. Descriptive statics were computed to summarize the participant's characteristics. Bi-variable and multivariable logistic regression analyses were conducted to identify the association between dependent and independent variables. Independent variables with a p-value of less than 0.05 were considered to be statistically significant at 95% confidence level (CI).

RESULTS

The proportion of HIV infection among pregnant women was 8.68% (95% CI: 6.5, 11.4). Completing secondary school education (Adjusted Odds Ratio (AOR = 0.15; 95% CI: 0.04-0.53), graduated from college (AOR = 0.03; 95% CI: 0.01-0.22), and family monthly income greater than 8001 ETB (1 USD = 56 ETB) (AOR = 0.19; 95% CI: 0.04-0.87) were protective factors associated with maternal HIV. On the other hand, history of previous abortion (AOR = 7.73; 95% CI: 3.33-17.95) and positive syphilis status (AOR = 10.28; 95% CI: 2.80-37.62) were risk factors associated with maternal HIV status.

CONCLUSION

The proportion of HIV infection among pregnant women was found to be high. Advanced level of education, relatively higher monthly income, history of abortion and previous syphilis status were associated factors with HIV status. Strengthening women's formal education; empowering women in all spheres of life (especially improving their economic standing that prevents women from engaging in risky sexual practices); educating women about HIV transmission methods and HIV prevention and control strategies using behavior change intervention strategy prepared for women to reduce their vulnerability; advocating for the use of family planning to reduce unsafe abortions and syphilis; as well as regular screening and testing for syphilis are recommended.

Investigation of the immune escape mechanism of Treponema pallidum

BACKGROUND

Syphilis is a chronic sexually transmitted disease caused by Treponema pallidum subspecies pallidum (T. pallidum), which is a public health problem that seriously affects human health worldwide. T. pallidum is characterized by early transmission and immune escape and is therefore termed an "invisible pathogen".

METHODS

This review systematically summarizes the host's innate and adaptive immune responses to T. pallidum infection as well as the escape mechanisms of T. pallidum.

PURPOSE

To lay the foundation for assessing the pathogenic mechanism and the systematic prevention and treatment of syphilis.

CONCLUSION

The immune escape mechanism of T. pallidum plays an important role in its survival. Exploring the occurrence and development of these mechanisms has laid the foundation for the development of syphilis vaccine.

Genital ulcers caused by sexually transmitted agents

Genital ulcers (GUs) represent a diagnostic challenge and can be secondary to neoplastic and inflammatory processes of different causes. Among those of infectious etiology, there are sexually transmitted infections (STIs), a very frequent reason for seeking the health service. The most common agents are herpes simplex virus and Treponema pallidum and, more rarely, Haemophilus ducreyi, Klebsiella granulomatis and Chlamydia trachomatis. A careful dermatological examination offers important diagnostic elements; however, atypical manifestations are very common. Distinctive characteristics of ulcers to look out for include their margin, edge, bottom, and base. Regional lymph node chain alterations should be evaluated regarding their number, size, mobility, consistency, inflammation, and pain on palpation. Diagnostic tests have variable sensitivity and specificity, and molecular tests are currently considered the reference exams. The rapid immunochromatographic tests represented a significant advance, as they can be performed with blood obtained from the digital pulp, offer results in up to 30 minutes, and do not require a laboratory structure. The treatment of persons affected by GU/STIs must be immediate, as it aims to prevent complications, as well as reduce transmission. It is not always considered that people with GUs/STIs have varying degrees of depression, anxiety, and self-reproach, with an impact on relationships. Establishing a bond and trusting the professional is essential for adherence to treatment and preventive measures that must be discussed individually.

A suite of PCR-LwCas13a assays for detection and genotyping of Treponema pallidum in clinical samples

The performance of commonly used assays for diagnosis of syphilis varies considerably depending on stage of infection and sample type. In response to the need for improved syphilis diagnostics, we develop assays that pair PCR pre-amplification of the tpp47 gene of Treponema pallidum subsp. pallidum with CRISPR-LwCas13a. The PCR-LwCas13a assay achieves an order of magnitude better analytical sensitivity than real-time PCR with equivalent specificity. When applied to a panel of 216 biological specimens, including 135 clinically confirmed primary and secondary syphilis samples, the PCR-LwCas13a assay demonstrates 93.3% clinical sensitivity and 100% specificity, outperforming tpp47 real-time PCR and rabbit-infectivity testing. We further adapt this approach to distinguish Treponema pallidum subsp. pallidum lineages and identify genetic markers of macrolide resistance. Our study demonstrates the potential of CRISPR-based approaches to improve diagnosis and epidemiological surveillance of syphilis.

Assessment of recombinant antigens Tp0100 and Tp1016 of Treponema pallidum for serological diagnosis of syphilis

Objective

To discover novel serodiagnostic candidates for the serological diagnosis of syphilis.

Methods

Two recombinant Treponema pallidum proteins Tp0100 and Tp1016 were expressed, purified, and identified by Western Blotting. A total of 600 clinical serum samples were tested with the Tp0100‐based ELISA, the Tp1016‐based ELISA, and the commercial LICA Syphilis TP kit (ChIVD, Beijing, China). The sensitivities were determined by testing 340 samples from individuals with clinically diagnosed primary, secondary, latent, and tertiary syphilis. The specificities were determined by screening 260 samples from healthy controls and individuals with potentially cross‐reactive infections, including leptospirosis, Lyme disease, hepatitis B, tuberculosis, rheumatoid arthritis, systemic lupus erythematosus. Kappa (κ) values were applied to compare the agreement between clinical syphilis diagnosis and the Tp0100‐based ELISA, the Tp1016‐based ELISA, or the LICA Syphilis TP test.

Results

Using clinical syphilis diagnosis as the gold standard, Tp0100 exhibited an overall sensitivity of 95.6% and specificity of 98.1% for testing IgG antibody while Tp1016 demonstrated only an overall sensitivity of 75.0% and specificity of 79.6%. In contrast, the LICA Syphilis TP test revealed an overall sensitivity of 97.6% and specificity of 96.2%. In addition, the overall percent agreement and corresponding κ values were 96.7% (95% CI 95.6%–97.8%) and 0.93 for the Tp0100‐based ELISA, 77.0% (95% CI 74.3%–79.7%) and 0.54 for the Tp1016‐based ELISA, and 97.0% (95% CI 96.0%–98.0%) and 0.94 for the LICA Syphilis TP test, respectively.

Conclusion

The recombinant T. pallidum protein Tp0100 shows promise as a novel diagnostic antigen in the serological tests for syphilis.

Fascinating Molecular and Immune Escape Mechanisms in the Treatment of STIs (Syphilis, Gonorrhea, Chlamydia, and Herpes Simplex)

The incidence of syphilis, gonorrhea, chlamydia, and herpes simplex has increased over the last decade, despite the numerous prevention strategies. Worldwide scientists report a surge in drug-resistant infections, particularly in immunocompromised patients. Antigenic variations in syphilis enable long-term infection, but benzathine penicillin G maintains its efficiency, whereas macrolides should be recommended with caution. Mupirocin and zoliflodacin were recently introduced as therapies against ceftriaxone-resistant gonococcus, which poses a larger global threat. The gastrointestinal and prostatic potential reservoirs of Chlamydia trachomatis may represent the key towards complete eradication. Similar to syphilis, macrolides resistance has to be considered in genital chlamydiosis. Acyclovir-resistant HSV may respond to the novel helicase-primase inhibitors and topical imiquimod, particularly in HIV-positive patients. Novel drugs can overcome these challenges while nanocarriers enhance their potency, particularly in mucosal areas. This review summarizes the most recent and valuable discoveries regarding the immunopathogenic mechanisms of these sexually transmitted infections and discusses the challenges and opportunities of the novel molecules and nanomaterials.

Detection A2058G and A2059G on the 23S rRNA Gene by Multiplex Nested PCR to Identify Treponema pallidum Resistance to Azithromycin in Indonesia

Azithromycin is one of the antibiotics used to treat syphilis, especially in the context of penicillin allergy. Resistance to azithromycin is widely reported associated with one and/or two point mutations on the 23S rRNA gene but has yet to be described in Indonesia. Specimens were collected from 220 patients diagnosed with secondary syphilis. A multiplex nested PCR testing system using the 23S rRNA target gene of Treponema pallidum was designed using three pairs of primers. The first step used PCR pairs of primers to detect T. pallidum. In the second step of PCR using 2 pairs of primers were achieved to identify azithromycin resistant T. pallidum based on A2058G and A2059G point mutations. There was no T.pallidum identified resistant to azithromycin in Jakarta and Bandung. T. pallidum resistance to azithromycin were found in Makassar, Medan, and Bali. The majority of azithromycin resistance was found among heterosexual males and in patients living with HIV. This study has demonstrated T. pallidum resistance to azithromycin in Indonesia appears to be a novel variant of resistance, containing both the A2058G and A2059G mutations that was found in Medan and Makassar.

Treponema pallidum (syphilis) antigen TpF1 induces activation of macrophages and accelerates P2X7R-induced NLRP3-dependent release of IL-1β

BACKGROUND

Syphilis is a chronic infectious disease caused by Treponema pallidum (Tp) infection, which causes local inflammation in the host. TpF1 is an oligomeric protein expressed by the Tp-infected host that can induce the host immune response. There are few studies regarding the role of TpF1 in macrophage activation and the subsequent release of cytokines.

OBJECTIVE

To elucidate the effects of TpF1 on the pathological process of Syphilis. In addition, we explored how purinergic 2X7 (P2X7R) induced NOD-like receptor family protein 3 (NLRP3) -dependent release of interleukin-1β (IL-1β) and the underlying mechanisms.

METHODS

We explored the influence of TpF1 on cytokine release by macrophages using qRT-PCR and ELISA. The specific phenotype of activated macrophages was determined by flow cytometry.

RESULTS

TpF1 was able to activate macrophages and induce the M1 macrophage phenotype. Moreover, TpF1 activated the NLRP3 inflammasome in macrophages, which was mediated by P2X7R.

CONCLUSIONS

The Tp-induced protein TpF1 is able to induce macrophage activation and P2X7R-induced NLRP3-dependent release of IL-1β. Our findings provide a theoretical basis for clarifying the clinical symptoms and pathogenesis of syphilis.

Bioactive Compounds as Potential Agents for Sexually Transmitted Diseases Management: A Review to Explore Molecular Mechanisms of Action

Sexually transmitted diseases (STDs) are produced by pathogens like bacteria, fungi, parasites, and viruses, and may generate severe health problems such as cancer, ulcers, and even problems in the newborn. This narrative review aims to present updated information about the use of natural bioactive compounds for the prevention and treatment of sexually transmitted infections. A search of the literature was performed using databases and search engines such as PubMed, Scopus, Google Scholar and Science Direct. From the pharmacotherapeutic management point of view, any strategies for prevention should contain medical approaches. The bioactive compounds obtained from natural products have shown biological effects against different microorganisms for the treatment of these diseases. The main results showed antimicrobial, antiprotozoal, antifungal and antiviral effects such as HIV. Also, the molecular mechanisms, signalling pathways and action targets of natural compounds were highlighted, thus justifying bacterial and antifungal inhibition, apoptosis or reduction of viral replication. From the data of our study, we can conclude that natural compounds may be a significant source for adjuvant drugs / complementary therapies in the treatment of STDs. With all these benefits, the future must conduct extensive clinical trials and the development of pharmaceutical nanotechnologies for a greater therapeutic effect.

Structural Modeling of the Treponema pallidum Outer Membrane Protein Repertoire: a Road Map for Deconvolution of Syphilis Pathogenesis and Development of a Syphilis Vaccine

Treponema pallidum, an obligate human pathogen, has an outer membrane (OM) whose physical properties, ultrastructure, and composition differ markedly from those of phylogenetically distant Gram-negative bacteria. We developed structural models for the outer membrane protein (OMP) repertoire (OMPeome) of T. pallidum Nichols using solved Gram-negative structures, computational tools, and small-angle X-ray scattering (SAXS) of selected recombinant periplasmic domains. The T. pallidum "OMPeome" harbors two "stand-alone" proteins (BamA and LptD) involved in OM biogenesis and four paralogous families involved in the influx/efflux of small molecules: 8-stranded β-barrels, long-chain-fatty-acid transporters (FadLs), OM factors (OMFs) for efflux pumps, and T. pallidum repeat proteins (Tprs). BamA (TP0326), the central component of a β-barrel assembly machine (BAM)/translocation and assembly module (TAM) hybrid, possesses a highly flexible polypeptide-transport-associated (POTRA) 1-5 arm predicted to interact with TamB (TP0325). TP0515, an LptD ortholog, contains a novel, unstructured C-terminal domain that models inside the β-barrel. T. pallidum has four 8-stranded β-barrels, each containing positively charged extracellular loops that could contribute to pathogenesis. Three of five FadL-like orthologs have a novel α-helical, presumptively periplasmic C-terminal extension. SAXS and structural modeling further supported the bipartite membrane topology and tridomain architecture of full-length members of the Tpr family. T. pallidum's two efflux pumps presumably extrude noxious small molecules via four coexpressed OMFs with variably charged tunnels. For BamA, LptD, and OMFs, we modeled the molecular machines that deliver their substrates into the OM or external milieu. The spirochete's extended families of OM transporters collectively confer a broad capacity for nutrient uptake. The models also furnish a structural road map for vaccine development. IMPORTANCE The unusual outer membrane (OM) of T. pallidum, the syphilis spirochete, is the ultrastructural basis for its well-recognized capacity for invasiveness, immune evasion, and persistence. In recent years, we have made considerable progress in identifying T. pallidum's repertoire of OMPs. Here, we developed three-dimensional (3D) models for the T. pallidum Nichols OMPeome using structural modeling, bioinformatics, and solution scattering. The OM contains three families of OMP transporters, an OMP family involved in the extrusion of noxious molecules, and two "stand-alone" proteins involved in OM biogenesis. This work represents a major advance toward elucidating host-pathogen interactions during syphilis; understanding how T. pallidum, an extreme auxotroph, obtains a wide array of biomolecules from its obligate human host; and developing a vaccine with global efficacy.

A Novel tp0548 Gene Type of Treponema pallidum Identified in Nanjing, China: Case Report and Review of Literature

BACKGROUND

The tp0548 gene, hypothesized to encode for an outer-membrane protein, was originally used in the enhanced Centers for Disease Control and Prevention typing for molecular typing of Treponema pallidum. It plays an important role in the molecular epidemiology of Treponema because it is not only an important locus of multiple typing approaches but also suitable for strain typing of multiple Treponema subspecies.

METHODS

A 27-year-old Chinese man attended the Institute of Dermatology, Chinese Academy of Medical Sciences Sexually Transmitted Disease Clinic in Nanjing, China, because of a genital ulcer and inguinal lymphadenopathy for 1 week. Workup consisted of microbiological and hematological investigations, and sequences analysis. The aims of this study were to describe a novel tp0548 sequence type "Qn" of this syphilis strain and to review all previously reported novel tp0548 genotypes.

RESULTS

We identified a novel tp0548 gene type in a genital ulcer in a patient with primary syphilis in Nanjing, China. Using sequence alignment, we further found that this novel sequence was closely similar to "Q." Following the nomenclature used in the enhanced Centers for Disease Control and Prevention typing methodology, the letters "Qn" was assigned to the new sequence type.

CONCLUSION

The novel tp0548 sequence type of T. pallidum not only expands the database up to 27 different sequence types but also indicates the substantial genetic diversity of the tp0548 gene sequence.

Molecular Characterization Based on MLST and ECDC Typing Schemes and Antibiotic Resistance Analyses of Treponema pallidum subsp. pallidum in Xiamen, China

In total, 49 clinical samples were analyzed using two typing schemes, Enhanced Centers for Disease Control and Prevention (ECDC) and multilocus sequence typing (MLST), to describe the molecular characteristics of circulating Treponema pallidum isolates in Xiamen between 2016 and 2017. In addition, genetic mutations potentially related to antibiotic resistance of T. pallidum were also analyzed. Forty five samples were fully typed by ECDC, and 14 different subtypes were detected. The most common subtype was 16d/f (24.4%), followed by 14d/f (20.0%). All forty nine samples were successfully typed by MLST, while only four allelic profiles were identified, including three SS14-like profiles and one Nichols-like profile. Among them, the major allelic profile was 1.1.8 (85.7%). Interestingly, the allelic profile 1.3.1 widespread in Europe and North America was not detected in this region. Additionally, A2058G mutation in 23S rRNA was found in all detectable samples (38/38), and no mutation in 16S rRNA was observed (36/36). Four non-synonymous single-nucleotide polymorphisms in penicillin-binding protein genes were found in the 35 samples eligible for Sanger sequencing. Among them, the variant in tp0500 (P564I) can only be found in the SS14-like isolates. Homoplastic changes in tp0760 (I415F/I415M) and tp0705 (A506V/A506T) were found. Moreover, the variant tp0705 A506V and the variant tp0705 A506T separately appeared in the SS14-like isolates and Nichols-like isolates, respectively. This study showed that the genotypes of T. pallidum isolates in Xiamen between 2016 and 2017 were different from those in other geographic areas. The resistance-related variants of T. pallidum isolates identified in this study could provide awareness for clinicians in the treatment of syphilis.

Characterization of Treponema pallidum Dissemination in C57BL/6 Mice

The spirochetal pathogen Treponema pallidum causes 5 million new cases of venereal syphilis worldwide each year. One major obstacle to syphilis prevention and treatment is the lack of suitable experimental animal models to study its pathogenesis. Accordingly, in this study, we further evaluated the responses of mice to Treponema pallidum. Quantitative polymerase chain reaction showed that Treponema pallidum could colonize the heart, liver, spleen, kidneys, and testicles of C57BL/6 mice, and the organism may be able to rapidly penetrate the blood-brain barrier in mice by 24 h after infection. In subsequent rabbit infectivity tests, we observed evident signs of the microorganism in the mouse lymph node suspension. After infection, bacterial loads were higher in the tissues than in the blood of C57BL/6 mice. Moreover, a significant Th1 immune response was recorded by cytokine assays. Flow cytometric analysis suggested an obvious increase in the proportion of CD3+ T and CD4+ T cells in the spleen cells in the infected mice. Thus, improving our understanding of the response of C57BL/6 mice for Treponema pallidum will help to comprehensive elucidate the pathogenic mechanisms of this bacterium and lay the foundation for the development of a new research model of Treponema pallidum.

Estimation of Full-Length TprK Diversity in Treponema pallidum subsp. pallidum

Syphilis continues to be a significant public health issue in both low- and high-income countries, including the United States where the rate of syphilis infection has increased over the past 5 years. Treponema pallidum subsp. pallidum, the causative agent of syphilis, carries the outer membrane protein TprK that undergoes segmental gene conversion to constantly create new sequences. We performed full-length deep sequencing of TprK to examine TprK diversity in clinical T. pallidum subsp. pallidum strains. We then combined our results with data from all samples for which TprK deep sequencing results were available. We found almost no overlap in TprK sequences between different patients. Moreover, our data allowed us to estimate the total number of TprK variants that T. pallidum subsp. pallidum can potentially generate. Our results support how the T. pallidum subsp. pallidum TprK antigenic variation system is an equal adversary of the human immune system leading to pathogen persistence in the host.

Immune evasion and disease progression of Treponema pallidum subsp. pallidum are associated with sequence diversity in the hypervariable outer membrane protein TprK. Previous attempts to study variation within TprK have sequenced at depths insufficient to fully appreciate the hypervariable nature of the protein, failed to establish linkage between the protein’s seven variable regions, or were conducted on isolates passed through rabbits. As a consequence, a complete profile of tprK during infection in the human host is still lacking. Furthermore, prior studies examining how T. pallidum subsp. pallidum uses its repertoire of genomic donor sites to generate diversity within the variable regions of the tprK have yielded a partial understanding of this process due to the limited number of tprK alleles examined. In this study, we used short- and long-read deep sequencing to directly characterize full-length tprK alleles from T. pallidum subsp. pallidum collected from early lesions of patients attending two sexually transmitted infection clinics in Italy. We demonstrate that strains collected from cases of secondary syphilis contain significantly more unique variable region sequences and full-length TprK sequences than those from cases of primary syphilis. Our data, combined with recent data available on Chinese T. pallidum subsp. pallidum specimens, show the near-complete absence of overlap in TprK sequences among the 41 specimens profiled to date. We further estimate that the potential antigenic variability carried by TprK rivals that of current estimates of the human adaptive immune system. These data underscore the immunoevasive ability of TprK that allows T. pallidum subsp. pallidum to establish lifelong infection.

2020 European guideline on the management of syphilis

The 2020 edition of the European guideline on the management of syphilis is an update of the 2014 edition. Main modifications and updates include: -The ongoing epidemics of early syphilis in Europe, particularly in men who have sex with men (MSM) -The development of dual treponemal and non-treponemal point-of-care (POC) tests -The progress in non-treponemal test (NTT) automatization -The regular episodic shortage of benzathine penicillin G (BPG) in some European countries -The exclusion of azithromycin as an alternative treatment at any stage of syphilis -The pre-exposure or immediate post-exposure prophylaxis with doxycycline in populations at high risk of acquiring syphilis.

Ancient Bacterial Genomes Reveal a High Diversity of Treponema pallidum Strains in Early Modern Europe

Syphilis is a globally re-emerging disease, which has marked European history with a devastating epidemic at the end of the 15^th century. Together with non-venereal treponemal diseases, like bejel and yaws, which are found today in subtropical and tropical regions, it currently poses a substantial health threat worldwide. The origins and spread of treponemal diseases remain unresolved, including syphilis' potential introduction into Europe from the Americas. Here, we present the first genetic data from archaeological human remains reflecting a high diversity of Treponema pallidum in early modern Europe. Our study demonstrates that a variety of strains related to both venereal syphilis and yaws-causing T. pallidum subspecies were already present in Northern Europe in the early modern period. We also discovered a previously unknown T. pallidum lineage recovered as a sister group to yaws- and bejel-causing lineages. These findings imply a more complex pattern of geographical distribution and etiology of early treponemal epidemics than previously understood.

Neurosyphilis in AIDS patient presenting as isolated cranial nerve 6 palsy

Early neurosyphilis can occur in an immunocompromised host. It has a widely varied presentation. Isolated CN6 as presenting symptom has not been described.

Enhanced molecular typing and macrolide and tetracycline-resistance mutations of Treponema pallidum in Barcelona

Aim: To describe the molecular types of Treponema pallidum and the proportion of macrolide and tetracycline resistance mutations in Barcelona. Materials & methods: Molecular type was determined using the Enhanced-CDC Typing system and antibiotic resistance was determined by sequencing the 23S and 16S rRNA genes. Results: A total of 183 patients were enrolled and 213 specimens (99 ulcers, 114 bloods) were collected. Sixty-two (70.5%) of 88 ulcers and 0 (0%) of bloods T. pallidum-DNA containing samples were fully typed. Up to 21 different strain types were identified (14d/g in 27.4%; 14f/g in 14.5%). Macrolide resistance mutations were present in 95% and tetracycline in 0%. Conclusion: Several different strains co-exist in Barcelona with a high proportion of macrolide resistance and absence of tetracycline resistance.

Advancing the understanding of treponemal disease in the past and present

Syphilis was perceived to be a new disease in Europe in the late 15th century, igniting a debate about its origin that continues today in anthropological, historical, and medical circles. We move beyond this age-old debate using an interdisciplinary approach that tackles broader questions to advance the understanding of treponemal infection (syphilis, yaws, bejel, and pinta). How did the causative organism(s) and humans co-evolve? How did the related diseases caused by Treponema pallidum emerge in different parts of the world and affect people across both time and space? How are T. pallidum subspecies related to the treponeme causing pinta? The current state of scholarship in specific areas is reviewed with recommendations made to stimulate future work. Understanding treponemal biology, genetic relationships, epidemiology, and clinical manifestations is crucial for vaccine development today and for investigating the distribution of infection in both modern and past populations. Paleopathologists must improve diagnostic criteria and use a standard approach for recording skeletal lesions on archaeological human remains. Adequate contextualization of cultural and environmental conditions is necessary, including site dating and justification for any corrections made for marine or freshwater reservoir effects. Biogeochemical analyses may assess aquatic contributions to diet, physiological changes arising from treponemal disease and its treatments (e.g., mercury), or residential mobility of those affected. Shifting the focus from point of origin to investigating who is affected (e.g., by age/sex or socioeconomic status) and disease distribution (e.g., coastal/ inland, rural/urban) will advance our understanding of the treponemal disease and its impact on people through time.

MicroRNA-101-3p Downregulates TLR2 Expression, Leading to Reduction in Cytokine Production by Treponema pallidum-Stimulated Macrophages

Treponema pallidum (Tp) infection-induced immune responses can cause tissue damage. However, the underlying mechanism by which Tp infection induces immune response is unclear. Recent studies suggest a regulatory role of microRNAs in host immunity. We assessed whether microRNAs also have a regulatory role in immune response to Tp infection in vitro. Our results showed that microRNA-101-3p (miR-101-3p) levels were significantly higher in peripheral blood mononuclear cells of patients with primary syphilis and those in the serofast state, whereas toll-like receptor (TLR) 2 levels were higher in patients with syphilis than in healthy controls. In vitro, stimulation of THP-1 cells with Tp increased miR-101-3p expression. Moreover, miR-101-3p reduced expression levels of TLR2 mRNA and protein in THP-1 cells via binding to the 3' untranslated region of TLR2. Likewise, miR-101-3p inhibited production of inflammatory cytokines, including IL-1β, IL-6, tumor necrosis factor-α, and IL-12, in Tp-stimulated macrophages. IL-1β and IL-6 mRNA expression levels were reduced by transfection of macrophages with a TLR2-specific small interfering RNA. Conversely, overexpression of TLR2 upregulated cytokine expression. Patients with secondary syphilis exhibited the highest levels of plasma IL-6, which were negatively correlated with miR-101-3p. In conclusion, Tp infection upregulates miR-101-3p expression, which in turn inhibits the TLR2 signaling pathway, leading to reduced cytokine production.

A comparison of nontreponemal tests in cerebrospinal fluid for neurosyphilis diagnosis: equivalent detection of specific antibodies

BACKGROUND

Syphilis is a re-emerging sexually-transmitted infection, caused by the spirochete Treponema pallidum, that may penetrate early into the central nervous system. The venereal disease research laboratory test (VDRL) on the cerebrospinal fluid (CSF) is the most widely used for neurosyphilis diagnosis. We evaluated the performance of two other nontreponemal tests (rapid plasma reagin [RPR] and unheated serum reagin [USR] tests) in comparison with the VDRL in CSF.

METHODS

We analyzed CSF samples from 120 individuals based on VDRL reactivity in the CSF and the clinical picture of neurosyphilis.

RESULTS

High inter-rater reliability was found among all three tests, with equivalent sensitivity and specificity. Intraclass correlation coefficient for absolute agreement was 1 for VDRL versus USR, 0.99 for VDRL versus RPR, and 0.99 for RPR versus USR.

CONCLUSIONS

Rapid plasma reagin and unheated serum reagin tests were identified as excellent alternatives for neurosyphilis diagnosis.

Pediatric otosyphilis—An unusual cause of conductive hearing loss

We present the case of a 5 year old female with a unilateral conductive hearing loss which had a relapsing and remitting course over a 3 year period. An initial noncontrast CT temporal bone study was unremarkable and a diagnosis of otitis media was made in the first instance. However, a second CT temporal bone study performed 3 years later demonstrated bilateral demineralisation of the ossicles and abnormal lucency affecting both the otic capsules. A diagnosis of otosyphilis was proposed on the basis of the imaging features and a prior medical history of previously treated congenital syphilis. With the benefit of hindsight, early pericochlear lucency was identified on the initial CT temporal bone study. There has been a steady rise of syphilis cases since the millennium with resurgence in many high income countries. Otosyphilis has a highly variable clinical presentation and there is limited data to establish the pattern of hearing loss in pediatric patients with a background of congenital otosyphilis. Temporal bone and otic capsule demineralisation carries a broad differential diagnosis including osteogenesis imperfecta, otosclerosis, Paget's disease and radiation related changes. Otosyphilis is a rare but potentially treatable cause of deafness and a high index of suspicion is required to make the diagnosis. In conjunction with a positive syphilis serology, a noncontrast temporal bone CT can aid the diagnosis and expedite the treatment.

Sero-epidemiology and risk factors of syphilis in Makassar, Indonesia

Introduction. Syphilis is an infectious disease caused by Treponema pallidum spirochete and is mainly transmitted by sexual contact. Syphilis has the potential to cause serious complications and is closely related to human immunodeficiency virus (HIV) infection thus making syphilis still a major public health problem. In Indonesia, surveys of high-risk populations in 2007 and 2011 reported an increase in the prevalence of syphilis, especially in men who have sexual relationships with other men (MSM). Moreover, studies have described risk factors for HIV transmission including MSM, heterosexual contacts, Intravenous (IV) drug use, and infected partners.

Objectives. To assess the epidemiological aspects and risk factors for syphilis in Makassar, as well as the correlation with a coinfection of other sexually transmitted infections.

Material and Methods. This study is a multi-centre cross-sectional descriptive study with consecutive sampling. We evaluated cases for eligibility by confirming the diagnosis based on the serological result using rapid plasma reagin assay (RPR), Treponema pallidum haemagglutination (TPHA), and HIV screening kit. The cases were analyzed based on epidemiological features, risk factors and clinical findings, co-infection with other sexually transmitted infection (ST), and stadium of the disease.

Results. A total of 79 serologically confirmed syphilis cases were collected between January 2017 and December 2018 in Makassar, the capital city of South Sulawesi province in Indonesia. Of the 63 male subjects (79.7%), 38 (48.1%) were homosexual/MSM, and in 41 cases of HIV-infected subjects, 25 (60.9%) of them were also MSM.

Conclusion. Our study showed there was a significant correlation between syphilis and an increased risk of HIV transmission in MSM groups. The higher number of cases of syphilis and HIV co-infection among MSM can increase transmission of both infections and should be considered a major risk factor for syphilis in Makassar.

The N-terminal D1 domain of Treponema pallidum flagellin binding to TLR5 is required but not sufficient in activation of TLR5

Syphilis is a chronic bacterial infection caused by Treponema pallidum (T pallidum) and the pathogenesis that T pallidum infection induces immunopathological damages in skin and other tissues remains unclear. We have previously reported that recombinant flagellins of T pallidum can elicit IL‐6 and IL‐8 transcriptions via TLR5 pathway. To identify the domains which induced the pro‐inflammatory activity and the importance of the interactions between TLR5 and domains, homology‐based modelling and comparative structural analyses revealed that Tpflagellins can combine with TLR5 directly. Deletion mutations showed that the ND1 domain binding to TLR5 is required but not sufficient in TLR5 activation. Moreover, site‐directed mutagenesis analysis indicated that the arginine residue (Tpflagellins R89) of the ND1 domain and its adjacent residues (Tpflagellins L93 and E113) constitute a hot spot that elicits IL‐6, IL‐8 transcriptions and TLR5 activation, and affects the binding of Tpflagellins to TLR5. Taken together, these results give insight into the pathogenesis of T pallidum and may contribute to the future design of Tpflagellins‐based therapeutics and syphilis vaccine.

Syphilitic Cervicitis with Cervical Cancer Presenting as Oropharyngeal Syphilis

We herein report a patient with syphilitic cervicitis and cervical cancer presenting as oropharyngeal syphilis. A 31-year-old Japanese woman with a history of unprotected vaginal and oral sex visited our hospital with right submandibular adenomas and erythema in the extremities. The fornix uteri was red, with a nodule noted. The rapid plasma reagin ratio was 1:3. She was diagnosed with syphilitic cervicitis and treated with amoxicillin for four weeks. Initial cervical cytology showed cells with mild nuclear enlargement, which was thought to be metaplasia associated with syphilis. Repeated cytology a month later showed a high-grade squamous intraepithelial lesion. A punch biopsy of the lesion led to the pathological diagnosis of cervical carcinoma in situ. We performed cervical conization, and no recurrence occurred. Human papillomavirus (HPV) immunostaining was positive in the lesion. Mucosal lesions are an infrequently reported symptom of syphilis. When oropharyngeal lesions are found, the sexual history should be ascertained, and the patient should be screened for sexually transmitted diseases. HPV is especially significant because of its association with cervical cancer. Coinfection of HPV with cervical cancer must be ruled out during follow-up for women when oropharyngeal syphilis involves genital lesions.

A Nonhuman Primate Model for Rectally Transmitted Syphilis

Among men who have sex with men (MSM), those with a diagnosis of syphilis or other rectal sexually transmitted infections (STIs) are at a higher risk for human immunodeficiency virus acquisition, which is concerning given the large increase in recently reported syphilis cases in the United States. We have developed the first nonhuman primate model for rectally transmitted syphilis by exposing simian/human immunodeficiency virus-infected and naive rhesus macaques to Treponema pallidum in the rectum. All animals showed mucosal lesions, systemic dissemination, and seroconversion (treponemal antibodies). This model would be valuable for studying the manifestations of and interventions for T. pallidum infection, with and without human immunodeficiency virus coinfection.

A lung abscess caused by secondary syphilis - the utility of polymerase chain reaction techniques in transbronchial biopsy: a case report

Background

In Japan and other countries, the number of patients with syphilis is increasing year by year. Recently, the cases of the pulmonary involvement in patients with secondary syphilis have been reported. However, it is still undetermined how to obtain a desirable specimen for a diagnosis of the pulmonary involvement, and how to treat it if not cured.

Case presentation

A 34-year-old man presented with cough and swelling of the right inguinal nodes. A physical examination revealed erythematous papular rash over the palms, soles and abdomen. A 4 cm mass in the right lower lobe of the lung was detected on computed tomography. He was diagnosed as having secondary syphilis, because he was tested positive for the rapid plasma reagin and Treponema pallidum hemagglutination assay. Amoxycillin and probenecid were orally administered for 2 weeks. Subsequently, rash and serological markers were improved, however, the lung mass remained unchanged in size. Transbronchial biopsy (TBB) confirmed the pulmonary involvement of syphilis using polymerase chain reaction techniques (tpp47- and polA-PCR). Furthermore, following surgical resection revealed the lung mass to be an abscess.

Conclusions

To our knowledge, this is the first surgically treated case of a lung abscess caused by syphilis, which was diagnosed by PCR techniques in TBB. This report could propose a useful diagnostic method for the pulmonary involvement of syphilis.

Viral hepatitis and Treponema pallidum prevalence in persons who underwent premarital blood tests in Argentina

The objective of this study was to estimate the prevalence of different serological markers of hepatitis A, B and C viruses and Treponema pallidum among the adult population of Argentina. To achieve this, adults who attended health services for premarital exams (which are mandatory and includes screening for syphilis) were recruited. A cross-sectional study was designed with a cluster sampling strategy. Couples who attended selected health services for premarital screening between 2013 and 2014 in Buenos Aires, Cordoba, Mendoza and Santa Fe provinces were included. A total of 3833 individuals were recruited. Anti-HAV prevalence was 63.9%, anti-HCV 0.3%, anti-HBc (without HBsAg) 1.9%, HBsAg 0.3%, and T pallidum 0.8%. Anti-HAV was higher among older participants, foreigners and those from the lower strata. HBV increased with age and was higher among foreigners and those with lower formal educational level. Anti-HCV frequency increased with age. Premarital screening of viral hepatitis could constitute an instance of diagnosis, vaccination and inclusion in care of those in need. Results from this study will allow the national hepatitis programs to design public policies in order to diminish the impact of these infections on the population.

Treponema pallidum Induces the Secretion of HDVSMC Inflammatory Cytokines to Promote the Migration and Adhesion of THP-1 Cells

The pathological features of syphilis, a disease caused by Treponema pallidum (T. pallidum), are characterized by vascular involvement with endarteritis and periarteritis. Little is known about the interactions of infiltrating immunocytes with human dermal vascular smooth muscle cells (HDVSMCs) in arterioles during the immunopathogenesis of syphilis. In the present study, we demonstrated that stimulation of HDVSMCs with T. pallidum resulted in the upregulated gene transcription and protein expression of interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1), and intercellular adhesion molecule-1 (ICAM-1) in a dose- and time-dependent manner. Moreover, the migration and adhesion of THP-1 cells to HDVSMCs were significantly suppressed by anti-MCP-1 and anti-ICAM-1 neutralizing antibodies, respectively. Further studies revealed that T. pallidum activated the NF-κB signaling pathway in HDVSMCs. Inhibition of NF-κB suppressed T. pallidum-induced IL-6, MCP-1, and ICAM-1 expression. In addition, the migration and adhesion of THP-1 cells to T. pallidum-treated HDVSMCs were significantly decreased by pretreatment with an NF-κB inhibitor. These findings demonstrate that T. pallidum induces the production of IL-6, MCP-1, and ICAM-1 in HDVSMCs and promotes the adherence and migration of THP-1 cells to HDVSMCs through the NF-κB signaling pathway, which may provide new insight into the pathogenesis of T. pallidum infection.

The Treponema pallidum Outer Membrane

The outer membrane (OM) of Treponema pallidum, the uncultivatable agent of venereal syphilis, has long been the subject of misconceptions and controversy. Decades ago, researchers postulated that T. pallidum's poor surface antigenicity is the basis for its ability to cause persistent infection, but they mistakenly attributed this enigmatic property to the presence of a protective outer coat of serum proteins and mucopolysaccharides. Subsequent studies revealed that the OM is the barrier to antibody binding, that it contains a paucity of integral membrane proteins, and that the preponderance of the spirochete's immunogenic lipoproteins is periplasmic. Since the advent of recombinant DNA technology, the fragility of the OM, its low protein content, and the lack of sequence relatedness between T. pallidum and Gram-negative outer membrane proteins (OMPs) have complicated efforts to characterize molecules residing at the host-pathogen interface. We have overcome these hurdles using the genomic sequence in concert with computational tools to identify proteins predicted to form β-barrels, the hallmark conformation of OMPs in double-membrane organisms and evolutionarily related eukaryotic organelles. We also have employed diverse methodologies to confirm that some candidate OMPs do, in fact, form amphiphilic β-barrels and are surface-exposed in T. pallidum. These studies have led to a structural homology model for BamA and established the bipartite topology of the T. pallidum repeat (Tpr) family of proteins. Recent bioinformatics has identified several structural orthologs for well-characterized Gram-negative OMPs, suggesting that the T. pallidum OMP repertoire is more Gram-negative-like than previously supposed. Lipoprotein adhesins and proteases on the spirochete surface also may contribute to disease pathogenesis and protective immunity.

Recombinant Treponema pallidum protein Tp47 promotes the migration and adherence of THP-1 cells to human dermal vascular smooth muscle cells by inducing MCP-1 and ICAM-1 expression

Vascular inflammation is a complex and multifactorial pathophysiological process that plays a crucial role in all stages of syphilis and is responsible for tissue damage. Little is known about the interactions of infiltrating immunocytes with human dermal vascular smooth muscle cells (HDVSMCs) in arterioles during the immunopathogenesis of syphilis. The Treponema pallidum subsp. pallidum membrane protein Tp47 is considered a major inducer of inflammation initiation and development. In this study, we demonstrated that Tp47 promoted the migration and adhesion of THP-1 cells to HDVSMCs. Furthermore, Tp47 increased monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1) mRNA and protein expression levels in a dose- and time-dependent manner. The migration and adhesion of THP-1 cells to HDVSMCs were significantly suppressed by anti-MCP-1 and anti-ICAM-1 neutralizing antibodies, respectively. Further studies revealed that treatment of HDVSMCs with Tp47 activated the PI3K/Akt, p38 MAPK and NF-κB signalling pathways. Inhibition of PI3K/Akt, p38 MAPK and NF-κB suppressed the MCP-1 and ICAM-1 expression induced by Tp47. In addition, the migration and adhesion of THP-1 cells to Tp47-treated HDVSMCs were significantly decreased by pretreatment with PI3K/Akt, p38 MAPK and NF-κB inhibitors. These findings demonstrate that Tp47 promotes the migration and adherence of THP-1 cells to HDVSMCs by inducing MCP-1 and ICAM-1 expression, which is mediated by activation of the PI3K/Akt, p38 MAPK and NF-κB pathways. This study provides a novel potential therapeutic strategy for controlling the vascular inflammatory response in syphilis patients.

Descriptive analysis of syphilis cases reported in Mato Grosso do Sul, Brazil identifies failure in treatment

INTRODUCTION

Syphilis infection remains an alarming public health problem worldwide.

METHODS

This study analyzed syphilis cases listed in the Information System on Diseases of Compulsory Declaration (SINAN) of Mato Grosso do Sul state in Brazil between January 2013 and December 2014.

RESULTS

Most of the evaluated syphilis cases would have been preventable through public education, particularly congenital syphilis in children of previously diagnosed mothers and infection by untreated sexual partners.

CONCLUSIONS

The incidence rate of syphilis could be reduced by improving prevention through counselling on the risk of infection, improving access to condoms, and increasing the frequency of diagnostic tests.

Comparative genomics of the transportome of Ten Treponema species

Treponema is a diverse bacterial genus, the species of which can be pathogenic, symbiotic, or free living. These treponemes can cause various diseases in humans and other animals, such as periodontal disease, bovine digital dermatitis and animal skin lesions. However, the most important and well-studied disease of treponemes that affects humans is 'syphilis'. This disease is caused by Treponema pallidum subspecie pallidum with 11-12 million new cases around the globe on an annual basis. In this study we analyze the transportome of ten Treponema species, with emphasis on the types of encoded transport proteins and their substrates. Of the ten species examined, two (T. primitia and T. azonutricium) reside as symbionts in the guts of termites; six (T. pallidum, T. paraluiscuniculi, T. pedis, T. denticola, T. putidum and T. brennaborense) are pathogens of either humans or animals, and T. caldarium and T. succinifaciens are avirulent species, the former being thermophilic. All ten species have a repertoire of transport proteins that assists them in residing in their respective ecological niches. For instance, oral pathogens use transport proteins that take up nutrients uniquely present in their ecosystem; they also encode multiple multidrug/macromolecule exporters that protect against antimicrobials and aid in biofilm formation. Proteins of termite gut symbionts convert cellulose into other sugars that can be metabolized by the host. As often observed for pathogens and symbionts, several of these treponemes have reduced genome sizes, and their small genomes correlate with their dependencies on the host. Overall, the transportomes of T. pallidum and other pathogens have a conglomerate of parasitic lifestyle-assisting proteins. For example, a T. pallidum repeat protein (TprK) mediates immune evasion; outer membrane proteins (OMPs) allow nutrient uptake and end product export, and several ABC transporters catalyze sugar uptake, considered pivotal to parasitic lifestyles. Taken together, the results of this study yield new information that may help open new avenues of treponeme research.

Enhanced Molecular Typing of Treponema pallidum subspecies pallidum Strains From 4 Italian Hospitals Shows Geographical Differences in Strain Type Heterogeneity, Widespread Resistance to Macrolides, and Lack of Mutations Associated With Doxycycline Resistance

BACKGROUND

Although syphilis rates have been relatively high in Italy for more than 15 years, no data on the molecular types of Treponema pallidum subspecies pallidum circulating in this country are yet available. Likewise, no data on how widespread is resistance to macrolide or tetracycline antibiotics in these strains exist. Such data would, however, promote comprehensive studies on the molecular epidemiology of syphilis infections in Italy and inform future interventions aiming at syphilis control in this and other European countries.

GOALS AND STUDY DESIGN

Swabs from oral, genital, cutaneous, or anal lesions were obtained from 60 syphilis patients attending dermatology clinics in Milan, Turin, Genoa, and Bologna. Molecular typing of T. pallidum DNA was performed to provide a snapshot of the genetic diversity of strains circulating in Northern Italy. Samples were also screened for mutations conferring resistance to macrolides and tetracyclines.

RESULTS

T. pallidum DNA was detected in 88.3% (53/60) of the specimens analyzed. Complete and partial T. pallidum typing data were obtained for 77.3% (41/53) and 15.0% (8/53) of samples, respectively, whereas 4 samples could not be typed despite T. pallidum DNA being detected. The highest strain type heterogeneity was seen in samples from Bologna and Milan, followed by Genoa. Minimal diversity was detected in samples from Turin, despite the highest number of typeable samples collected there. Resistance to macrolides was detected in 94.3% (50/53) of the strains, but no known mutations associated with tetracycline resistance were found.

CONCLUSIONS

Genetic diversity among T. pallidum strains circulating in Northern Italy varies significantly among geographical areas regardless of physical distance. Resistance to macrolides is widespread.

Urea-mediated dissociation alleviate the false-positive Treponema pallidum-specific antibodies detected by ELISA

The serological detection of antibodies to Treponema pallidum is essential to the diagnosis of syphilis. However, for the presence of cross-reaction, the specific antibody tests [e.g., enzyme-linked immunosorbent assay (ELISA)] always have false-positive results. In this study, we derived and validated the dissociation of urea in an attempt to alleviate the situation of false-positive antibodies to T. pallidum detected by ELISA. Six serum samples that were false-positive antibodies to T. pallidum detected by ELISA, and 16 control serum samples (8 sera positive for both specific IgG and IgM, and 8 IgG-positive and IgM-negative sera) were collected to select the appropriate dissociated concentration and time of urea. Our goal was to establish improved an ELISA method based on the original detection system of ELISA. The sensitivity of the improved ELISA was evaluated by 275 serum samples with class IgM-positive antibodies to T. pallidum. At 6 mol/L with 10 minutes dissociation of urea, 6 samples with false-positive antibodies to T. pallidum were converted to negative, and compared with true-positive antibodies to T. pallidum. The sensitivity of the improved ELISA was 100% by detecting the class IgM-positive antibodies to T. pallidum in sera of patients with syphilis. Considering the importance at the diagnosis of syphilis, antibodies to T. pallidum in serum samples should be retested by the improved ELISA method to avoid false-positive results.