Syphilis and cardiovascular risk: a Taiwanese registry.

BACKGROUND AND AIMS: Studies on the impact of syphilis on the cardiovascular system in large populations are limited. This study investigated the effects of syphilis on cardiovascular outcomes. METHODS: Medical records from 2010 to 2015 were retrieved from the Taiwan National Health Insurance Research Database, linked to the Notifiable Infectious Diseases database from the Taiwan Centers for Disease Control. Patients with syphilis were identified, excluding those with missing information, under 20 years of age, or with a history of human immunodeficiency virus infection, acute myocardial infarction, heart failure, aortic regurgitation, replacement of the aortic valve, aneurysm and/or dissection of the aorta, atrial fibrillation, ischaemic stroke, haemorrhagic stroke, and venous thromboembolism. Primary outcomes included new-onset acute myocardial infarction, heart failure, aortic regurgitation, aneurysm and dissection of the aorta, atrial fibrillation, ischaemic stroke, haemorrhagic stroke, venous thromboembolism, cardiovascular death, and all-cause mortality. RESULTS: A total of 28 796 patients with syphilis were identified from 2010 to 2015. After exclusions and frequency matching, 20 601 syphilis patients and 20 601 non-syphilis patients were analysed. The relative rate (RR) was utilized in the analysis, as the competing risk of death was not considered. Compared with patients without syphilis, patients with syphilis had increased risks of acute myocardial infarction (RR 38%, 95% confidence interval [CI] 1.19-1.60, P < .001), heart failure (RR 88%, 95% CI 1.64-2.14, P < .001), aortic regurgitation (RR 81%, 95% CI 1.18-2.75, P = .006), atrial fibrillation (RR 45%, 95% CI 1.20-1.76, P < .001), ischaemic stroke (RR 68%, 95% CI 1.52-1.87, P < .001), haemorrhagic stroke (RR 114%, 95% CI 1.74-2.64, P < .001), venous thromboembolism (RR 67%, 95% CI 1.23-2.26, P = .001), cardiovascular death (RR 155%, 95% CI 2.11-3.08, P < .001), and all-cause death (RR 196%, 95% CI 2.74-3.19, P < .001) but not for aneurysm and dissection of the aorta. CONCLUSIONS: This study demonstrates that patients with syphilis have a higher risk of cardiovascular events and all-cause mortality compared with those without syphilis.

Congenital Syphilis: a Review of Global Epidemiology.

In 2007, the World Health Organization (WHO) launched a global health initiative for the elimination of mother-to-child transmission (MTCT) of syphilis. This condition is highly preventable through antenatal identification of syphilis infection and treatment with penicillin during pregnancy. This review summarizes the global status of MTCT of syphilis and concludes that this condition remains a significant issue worldwide. There are large variations in case rates by region, with the highest numbers of cases in the African and Eastern Mediterranean regions, where there are also the least data available. There are also pockets of high-incidence areas within the other regions. Although the general trend is of decreasing rates over time, there are concerning indications of consistently increasing congenital syphilis cases in some areas, particularly in areas which have previously had very low case numbers. A concerted effort will be required to achieve the 2007 WHO goal of worldwide elimination of MTCT of syphilis in the near future.

Syphilis Prevalence, Incidence, and Demographic Differences in a Longitudinal Study of Young Sexual and Gender Minority Adults Assigned Male at Birth.

BACKGROUND: Syphilis rates in the United States have increased. Few studies have examined syphilis incidence and prevalence prospectively among young sexual and gender minorities (YSGM). METHODS: This study of YSGM assigned male at birth comes from a Chicago-based prospective cohort at 2 visits 6 months apart (N = 882). Syphilis cases were identified through serologic test results and self-reported history. RESULTS: In this sample, 25.1% had a lifetime prevalence, and 3.3% were incident cases with a crude incidence rate of 6.76 per 100 person-years. CONCLUSIONS: Lifetime syphilis and incidence are high in this sample of YSGM relative to general population samples.

Genomic Epidemiology of Treponema pallidum and Circulation of Strains With Diminished tprK Antigen Variation Capability in Seattle, 2021-2022.

BACKGROUND: The incidence of syphilis continues to increase in the United States, yet little is known about Treponema pallidum genomic epidemiology within American metropolitan areas. METHODS: We performed whole-genome sequencing and tprK deep sequencing of 28 T. pallidum-containing specimens, collected mostly from remnant Aptima swab specimens from 24 individuals from Seattle Sexual Health Clinic during 2021-2022. RESULTS: All 12 individuals infected with Nichols-lineage strains were men who have sex with men, while a specific SS14 cluster (mean, 0.33 single-nucleotide variant) included 1 man who has sex with women and 5 women. All T. pallidum strains sequenced were azithromycin resistant via 23S ribosomal RNA A2058G mutation. Identical T. pallidum genomic sequences were found in pharyngeal and rectal swab specimens taken concurrently from the same individuals. The tprK sequences were less variable between patient-matched specimens and between epidemiologically linked clusters. We detected a 528-base pair deletion in the tprK donor site locus, eliminating 9 donor sites, in T. pallidum genomes of 3 individuals with secondary syphilis, associated with diminution of TprK diversity. CONCLUSIONS: We developed an end-to-end workflow for public health genomic surveillance of T. pallidum from remnant Aptima swab specimens. tprK sequencing may assist in linking cases beyond routine T. pallidum genome sequencing. T. pallidum strains with deletions in tprK donor sites currently circulate and are associated with diminished TprK antigenic diversity.

Clinical presentation of early syphilis and genomic sequences of Treponema pallidum strains in patient specimens and isolates obtained by rabbit inoculation.

BACKGROUND: The global resurgence of syphilis necessitates vaccine development. METHODS: We collected ulcer exudates and blood from 17 primary syphilis (PS) participants and skin biopsies and blood from 51 secondary syphilis (SS) participants in Guangzhou, China for Treponema pallidum subsp. pallidum (TPA) qPCR, whole genome sequencing (WGS), and isolation of TPA in rabbits. RESULTS: TPA DNA was detected in 15 of 17 ulcer exudates and 3 of 17 blood PS specimens. TPA DNA was detected in 50 of 51 SS skin biopsies and 27 of 51 blood specimens. TPA was isolated from 47 rabbits with success rates of 71% (12/17) and 69% (35/51), respectively, from ulcer exudates and SS bloods. We obtained paired genomic sequences from 24 clinical samples and corresponding rabbit isolates. Six SS14- and two Nichols-clade genome pairs contained rare discordances. Forty-one of the 51 unique TPA genomes clustered within SS14 subgroups largely from East Asia, while 10 fell into Nichols C and E subgroups. CONCLUSIONS: Our TPA detection rate was high from PS ulcer exudates and SS skin biopsies and over 50% from SS blood, with TPA isolation in over two-thirds of samples. Our results support the use of WGS from rabbit isolates to inform vaccine development.

The incidence of new cases of syphilis has skyrocketed globally in the twenty-first century. This global resurgence requires new strategies, including vaccine development. As part of an NIH funded Cooperative Research Center to develop a syphilis vaccine, we established a clinical research site in Guangzhou, China to better define the local syphilis epidemic and obtain samples from patients with primary and secondary syphilis for whole genome sequencing (WGS) of circulating Treponema pallidum strains. Inoculation of rabbits enabled us to obtain T. pallidum genomic sequences from spirochetes disseminating in blood, a compartment of immense importance for syphilis pathogenesis. Collectively, our results further clarify the molecular epidemiology of syphilis in southern China, enrich our understanding of the manifestations of early syphilis, and demonstrate that the genomic sequences of spirochetes obtained by rabbit inoculation accurately represent those of the spirochetes infecting the corresponding patients.

Treponema pallidum Periplasmic and Membrane Proteins Are Recognized by Circulating and Skin CD4+ T Cells.

BACKGROUND: Histologic and serologic studies suggest the induction of local and systemic Treponema pallidum-specific CD4+ T-cell responses to T. pallidum infection. We hypothesized that T. pallidum-specific CD4+ T cells are detectable in blood and in the skin rash of secondary syphilis and persist in both compartments after treatment. METHODS: Peripheral blood mononuclear cells collected from 67 participants were screened by interferon-γ (IFN-γ) ELISPOT response to T. pallidum sonicate. T. pallidum-reactive T-cell lines from blood and skin were probed for responses to 89 recombinant T. pallidum antigens. Peptide epitopes and HLA class II restriction were defined for selected antigens. RESULTS: We detected CD4+ T-cell responses to T. pallidum sonicate ex vivo. Using T. pallidum-reactive T-cell lines we observed recognition of 14 discrete proteins, 13 of which localize to bacterial membranes or the periplasmic space. After therapy, T. pallidum-specific T cells persisted for at least 6 months in skin and 10 years in blood. CONCLUSIONS: T. pallidum infection elicits an antigen-specific CD4+ T-cell response in blood and skin. T. pallidum-specific CD4+ T cells persist as memory in both compartments long after curative therapy. The T. pallidum antigenic targets we identified may be high-priority vaccine candidates.

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.

In-Depth Proteome Coverage of In Vitro-Cultured Treponema pallidum and Quantitative Comparison Analyses with In Vivo-Grown Treponemes.

Previous mass spectrometry (MS)-based global proteomics studies have detected a combined total of 86% of all Treponema pallidum proteins under infection conditions (in vivo-grown T. pallidum). Recently, a method was developed for the long-term culture of T. pallidum under in vitro conditions (in vitro-cultured T. pallidum). Herein, we used our previously reported optimized MS-based proteomics approach to characterize the T. pallidum global protein expression profile under in vitro culture conditions. These analyses provided a proteome coverage of 94%, which extends the combined T. pallidum proteome coverage from the previously reported 86% to a new combined total of 95%. This study provides a more complete understanding of the protein repertoire of T. pallidum. Further, comparison of the in vitro-expressed proteome with the previously determined in vivo-expressed proteome identifies only a few proteomic changes between the two growth conditions, reinforcing the suitability of in vitro-cultured T. pallidum as an alternative to rabbit-based treponemal growth. The MS proteomics data have been deposited in the MassIVE repository with the data set identifier MSV000093603 (ProteomeXchange identifier PXD047625).

Ocular syphilis in patients with nonreactive RPR and positive treponemal serologies: a retrospective observational cohort study.

BACKGROUND: Screening for syphilis increasingly relies on positive treponemal rather than nontreponemal tests (rapid plasma reagin [RPR]). We compared ocular syphilis in patients with nonreactive versus positive RPR. METHODS: We conducted a retrospective observational cohort study of ocular syphilis treated at two New England hospitals 1996-2021 based on ophthalmologist-diagnosed eye findings and positive treponemal serology, regardless of RPR. We excluded patients with alternative diagnoses. We categorized RPR into nonreactive RPR, low-titer RPR (<1:8), and high-titer RPR (≥1:8) and compared early and long-term response to therapy. RESULTS: Our sample included 115 patients with ocular syphilis (median follow-up 2.5 years): 25 (22%) nonreactive RPR, 21 (18%) low-titer RPR, 69 (60%) high-titer RPR. Compared with nonreactive and low-titer RPR, people with high-titer RPR were younger (mean 47 years, p<0.001), more likely male (93%, p<0.001) and more likely to be living with HIV (49%, p<0.001). People with nonreactive and low-titer RPR were less likely than high-titer RPR to have posterior/panuveitis (32% and 29% versus 75%, p<0.001) or abnormal CSF (26% and 35% versus 75%, p<0.001), and more likely to present with chronic eye findings (20% and 29% versus 1%, p<0.001). In long-term follow up, eye findings improved and did not recur in most patients (62% nonreactive, 68% low-titer, 96% high-titer RPR); improved but recurred in 29%, 11%, and 4%, respectively; and were stable in 10%, 21%, and 0%, respectively. CONCLUSION: Patients with ocular syphilis and nonreactive RPR are similar to patients with low-titer RPR, and antibiotic therapy is beneficial in most.

Filling in the Gaps: Updates on Doxycycline Prophylaxis for Bacterial Sexually Transmitted Infections.

Over the past two decades, cases of sexually transmitted infections (STIs) due to syphilis, gonorrhea, and chlamydia have been rising in the United States, disproportionately among gay, bisexual, and other men who have sex with men (MSM), as well as racial and ethnic minorities of all genders. In this review, we address updates about the evidence on doxycycline post-exposure prophylaxis (doxy-PEP) for prevention of bacterial STIs, including efficacy, safety, antimicrobial resistance (AMR), acceptability, modeling population impact, and evolving guidelines for use. Equitable implementation of doxy-PEP will require evaluation of who is offered and initiates it, understanding patterns of use and longer-term STI incidence and AMR, provider training, and tailored community education.

Risk for Donor-Derived Syphilis after Kidney Transplantation, China, 2007-2022.

To evaluate the risk of acquiring syphilis from a donated kidney, we evaluated kidney transplantation pairs from West China Hospital, Sichuan, China, during 2007-2022. Donor-derived syphilis was rare. Risk may be higher if donors have active syphilis and may be reduced if recipients receive ceftriaxone.

Relapsed Mpox Keratitis, St. Louis, Missouri, USA.

We describe a case of a 46-year-old man in Missouri, USA, with newly diagnosed advanced HIV and PCR-confirmed mpox keratitis. The keratitis initially resolved after intravenous tecovirimat and penicillin for suspected ocular syphilis coinfection. Despite a confirmatory negative PCR, he developed relapsed, ipsilateral PCR-positive keratitis and severe ocular mpox requiring corneal transplant.

Congenital Syphilis Prevention Challenges, Pacific Coast of Colombia, 2018-2022.

High incidences of congenital syphilis have been reported in areas along the Pacific coast of Colombia. In this retrospective study, conducted during 2018-2022 at a public hospital in Buenaventura, Colombia, we analyzed data from 3,378 pregnant women. The opportunity to prevent congenital syphilis was missed in 53.1% of mothers because of the lack of syphilis screening. Characteristics of higher maternal social vulnerability and late access to prenatal care decreased the probability of having >1 syphilis screening test, thereby increasing the probability of having newborns with congenital syphilis. In addition, the opportunity to prevent congenital syphilis was missed in 41.5% of patients with syphilis because of the lack of treatment, which also increased the probability of having newborns with congenital syphilis. We demonstrate the urgent need to improve screening and treatment capabilities for maternal syphilis, particularly among pregnant women who are more socially vulnerable.

Could ceftriaxone be a viable alternative to penicillin for the treatment of ocular syphilis?

This study was conducted to compare the effectiveness of ceftriaxone with that of aqueous crystalline penicillin G in treating ocular syphilis. We conducted a retrospective study from 2010 to 2021. Syphilis patients were administered either ceftriaxone (2 g intravenously daily for 14 days) or aqueous crystalline penicillin G [4 million units (MU) intravenously every 4 h for 14 days] as therapeutic interventions. Subsequently, we utilized these two groups to assess the serological results, cerebrospinal fluid analysis, and visual acuity at time intervals spanning 3 to 6 months post-treatment. A total of 205 patients were included, with 34 assigned to the ceftriaxone group and 171 to the penicillin group. The median age of patients was 56 years, with an interquartile range of 49-62 years, and 137 of them (66.8%) were male. Between 3 and 6 months after treatment, 13 patients (38.2%) in the ceftriaxone group and 82 patients (48.0%) in the penicillin group demonstrated effective treatment based on the clinical and laboratory parameters. The crude odds ratio (OR) was 0.672 (95% confidence interval [CI]: 0.316-1.428, P = 0.301), indicating no significant difference in effectiveness between the two groups. Thirty patients (17.5%) in the penicillin group and six patients (17.6%) in the ceftriaxone group did not experience successful outcomes. Notably, no serious adverse effects were reported in both the groups. There was no significant difference in the effectiveness of ceftriaxone and aqueous crystalline penicillin G in treating ocular syphilis. The administration of ceftriaxone without requiring hospitalization presents a convenient and safe alternative treatment option for ocular syphilis.

Improved efficiency using sequential automated immunoassays for syphilis screening in blood donors.

Using sequential immunoassays for the screening of blood donors is well described for viral serology testing but not for the screening of syphilis. In this study, we report the evaluation results and 2-year sequential testing data using two highly sensitive automated serology assays, the Alinity s Syphilis chemiluminescent immunoassay for screening, with all repeatedly reactive samples then tested on the Elecsys Syphilis electrochemiluminescence immunoassay. We screened 1,767,782 blood donor samples between 7 July 2021 and 6 July 2023 and found the Alinity false-positive rate to be low at 0.08% (1,456/1,767,782). The common false-positive rate between the two assays was also low (3.83%, 58/1,514). Concordantly reactive samples were further tested using a Treponema pallidum particle agglutination test, a rapid plasma reagin test, and a fluorescent treponemal antibody absorption test. There were 262/1,376 concordantly reactive Alinity and Elecsys blood donor samples with reactivity on one or more of the confirmatory tests. A total of 26/1,376 donors had a current syphilis infection, 152/1,376 reported a past history of syphilis and had been treated, and 84/1,376 did not report a past history of syphilis. We suggest that future studies could explore the use of sequential immunoassays to aid in the serodiagnosis for syphilis. IMPORTANCE: The serodiagnosis for syphilis usually follows two methodologies-a "traditional" algorithm using a non-treponemal test followed by confirmation using a treponemal test, or a "reverse" algorithm using a treponemal test followed by a non-treponemal test. There are limited reports in the literature of using a modified reverse algorithm (treponemal test followed by a second treponemal test), and to the best of knowledge, there are currently no published articles using two highly sensitive automated immunoassays to aid the serodiagnosis of syphilis. In addition, the Treponema pallidum particle agglutination (TPPA) assay is commonly used as a confirmatory test for the diagnosis of syphilis. With the withdrawal of the TPPA assay from Australia and presumably from the global market also, alternative testing algorithms are now required. This study provides proof of concept for using sequential immunoassays in the diagnosis of syphilis.

Anti-Neuron-Derived Neurotrophic Factor Antibodies in Secondary Membranous Nephropathy Caused by Syphilis: A Case Report.

We present the case of a 61-year-old man who developed nephrotic syndrome as a result of syphilis-associated secondary membranous nephropathy (MN). The patient showed nephrotic syndrome remission following antibiotic treatment for syphilis alone. Pathologically, the target antigen of immune complexes accumulated on glomerular basement membranes (GBM) in secondary MN caused by syphilis has been reported to be neuron-derived neurotrophic factor (NDNF). His renal histopathology was consistent with secondary MN caused by syphilis, with a full-house pattern on immunofluorescence microscopy, in addition to NDNF deposits that colocalized with IgG deposits granularly on the GBM. However, to date, there is no serological evidence for the involvement of NDNF in the GBM. In the present study, we found that anti-NDNF autoantibodies in the acute-phase serum disappeared in the convalescent-phase serum of a patient who recovered from syphilis and nephrotic syndrome after antibiotic therapy alone. This result supports the hypothesis that treatment of syphilis with antibiotics suppresses NDNF's antigenicity. In summary, we found new serological evidence emphasizing that NDNF is an etiological antigen in secondary MN caused by syphilis.

Improvement and exacerbation of multiple disparities in sexually transmitted infections among children and adolescents aged 6-22 years: An analysis of national surveillance data from 2013 to 2021.

To investigate the progress of disparities in human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), gonorrhea, and syphilis among children and adolescents aged 6-22 years in China during 2013-2021. A total of 614 325 cases data were extracted from the Chinese Information System for Infectious Diseases Control and Prevention during 2013-2021. Puberty health education data were drew from the Student Health Surveillance in 2021. Disparity patterns and average annual percentage changes (AAPCs) in sexually transmitted infections (STIs) incidence or new cases in China were examined using descriptive statistics and joinpoint regression. The incidence across 345 cities was stratified by gross domestic product (GDP). Between 2013 and 2021, there were 614 325 reported cases of HIV/AIDS, gonorrhea, and syphilis among children and adolescents aged 6-22, with an annual average incidence of 24.0967 per 100 000. The expansion of HIV/AIDS has halted, yet the surge in gonorrhea and syphilis remains notably pronounced. The ratio of male to female AIDS incidence increased from 2.75 (2.60, 2.90) to 7.13 (6.68, 7.62), but that of syphilis changed from 0.33 (0.32, 0.34) to 0.56 (0.55, 0.57). Students and out-of-school individuals aged 13-15 experienced a notably high increase in STI cases, surpassing other age groups, with an average annual percentage increase of 29.2% and 26.3%, respectively. Nonstudents consistently had a higher incidence rate than students, with an IRR reaching 31.80 (31.24, 32.37) in 2021. A noticeable clustering pattern of new cases emerged in the southeastern region of the Heihe-Tengchong line, extending inland from the coastal areas. Districts and counties with lower rates of puberty sexual health education tended to have higher average STI incidence rates. At the prefecture and city levels, there was a noticeable upward trend on average STI incidence rates in cities with per capita GDPs. Strategies to address those disparities include promoting equitable health education, and widespread sexual health education, particularly in areas with limited access to education and experiencing rapid economic development. The effectiveness of sexual health education intervention needs to be further evaluated in well-designed studies.

Clinical spectrum of late symptomatic neurosyphilis in China: an 11-year retrospective study.

OBJECTIVES: This study aimed to describe the clinical features of neurosyphilis in Chinese patients in an attempt to find clinical features that are helpful for the early identification of neurosyphilis. METHODS: This retrospective study included people with syphilis who visited Shanghai Skin Disease Hospital between January 2010 and December 2020. Lumbar puncture was performed on those who met the inclusion and exclusion criteria. The diagnosis of neurosyphilis was based on clinical and laboratory findings. The parameters were analysed statistically. RESULTS: Of the 3524 patients with neurosyphilis, 2111 (59.9%) and 1413 (40.1%) were asymptomatic and symptomatic neurosyphilis, respectively. General paresis was the most common type of symptomatic neurosyphilis (46.8%). The clinical manifestations of symptomatic neurosyphilis include psychiatric and neurotic symptoms, among which general paresis predominantly presented as psychiatric symptoms such as affective (66.7%) and memory disorder (72.9%). Tabes dorsalis is often presented as neurotic symptoms. One hundred fifty patients (10.6%) with symptomatic neurosyphilis presented candy signs, a rare and specific neurosyphilis symptom that is common in general paresis. Girdle sensation was presented in 13 patients, mainly with tabes dorsalis, which had not been reported in previous studies. CONCLUSIONS: Notably, the candy sign is identified as a specific symptom of general paresis, while girdle sensations are highlighted as a particular symptom of tabes dorsalis. This is the largest study describing the clinical spectrum of neurosyphilis since the onset of the penicillin era and could help doctors learn more about the disease. A comprehensive description of the possible clinical manifestations of late symptomatic neurosyphilis, particularly highlighting rare symptoms, can identify suspicious patients and prevent diagnostic delays.

Multicentric evaluation of a specific intrathecal anti-Treponema pallidum IgG index as a diagnostic biomarker of neurosyphilis: results from a retro-prospective case-control study.

BACKGROUND AND OBJECTIVES: The diagnosis of neurosyphilis (NS) lacks a true 'gold standard', making the diagnosis challenging while consequences of a misdiagnosis are potentially severe. The aim of this study was to evaluate the diagnostic performance of measuring an antibody index (AI) for the intrathecal synthesis of specific anti-Treponema pallidum (T. pallidum) IgG for the diagnosis of NS. METHODS: Specific anti-T. pallidum IgG were measured simultaneously in paired cerebrospinal fluid (CSF)-serum samples collected retrospectively and prospectively between 2007 and 2022, from patients suspected of NS, in Switzerland. An AI was calculated to account for blood-brain barrier integrity. Area under the receiver operating characteristic curve, sensitivity/specificity and positive/negative predictive values of AI test were estimated. Two NS definitions were used: NS1 included patients with NS suspicion presenting with neurological symptoms and/or acute neurosensory signs, and positive T. Pallidum Hemagglutinations Assay (TPHA)/T. pallidum particle agglutination assay (TPPA) serology and CSF-TPHA/TPPA ≥320, and either CSF-leucocytes >5 cells/mm3 and/or CSF-protein >0.45 g/L and/or a reactive CSF-venereal disease research laboratory (VDRL)/rapid plasma reagin (RPR) test. NS2 included patients with suspected NS presenting with acute ocular and/or otologic symptoms, and positive TPHA/TPPA serology, and a favourable response to NS treatment. Controls were patients diagnosed with any other central nervous system (CNS) pathologies and with positive TPHA/TPPA serology. RESULTS: The study included 71 NS (43 NS1 and 28 NS2) and 110 controls. With a threshold of ≥1.7, sensitivity and specificity of the specific AI test were 90.7% (CI 77.7 to 97.4) and 100% (CI 96.7 to 100.0), respectively, for NS1 and 14.3% (CI 4 to 32.7) and 100% (CI 96.7 to 100.0) for NS2. In patients suspected of NS with a CNS involvement (NS1 group), NS could be confirmed by the positivity of this specific AI. CONCLUSIONS: Measurement of an intrathecal synthesis index of specific anti-T. pallidum IgG in patients with CSF inflammatory signs appears to be a valuable diagnostic test. However, in otic or ocular syphilis, presenting few CSF abnormalities, AI is not sufficient alone to confirm NS diagnosis. TRIAL REGISTRATION: Swiss Association of Research Ethics Committees number 2019-00232.

Seroconversion in syphilis screening without positive confirmatory tests points at early infection.

INTRODUCTION: The chemiluminescence immunoassay (CLIA) is a widely used screening test for syphilis. A CLIA seroconversion in the absence of a positive line immunoassay (LIA) or rapid plasma reagin (RPR) could indicate either an early incubating syphilis or a false positive result. We aimed to evaluate the diagnostic value of such seroconversions. METHODS: We retrospectively analysed data of clients visiting the Centre for Sexual Health Amsterdam between July 2013 and August 2021 with a positive CLIA and a negative RPR and negative or indeterminate LIA (at time To), and a preceding visit (T-1) with a negative CLIA <6 months of To ('unconfirmed CLIA seroconversion'). If available, data of follow-up visits (T1) <2 months of To were also included. A syphilis diagnosis was confirmed if darkfield microscopy or PCR for Treponema pallidum was positive at T0 or T1, or if RPR and/or LIA were positive at T1. RESULTS: We included data of 107 clients with unconfirmed CLIA seroconversion. The value of CLIA seroconversion could not be established in 13 (12.1%) clients. In the remaining 94 clients, the unconfirmed CLIA seroconversion was confirmed as early syphilis in 72 (76.6%) clients and probable syphilis in 6 (6.4%) clients. In 16 (17.0%) clients, the unconfirmed CLIA seroconversion was regarded as a false positive reaction of whom 4 (5.3%) clients had a seroreversion of the CLIA at T1. CONCLUSION: The majority of unconfirmed CLIA seroconversions represented early syphilis infections. Therefore, additional T. pallidum PCR, a follow-up consultation or early treatment is recommended.