Sensitivity and Specificity of Treponemal-specific Tests for the Diagnosis of Syphilis

Evaluating the clinical utility of semi-quantitative luciferase immunosorbent assay using Treponema pallidum antigens in syphilis diagnosis and treatment monitoring

To assess the clinical applicability of a semi-quantitative luciferase immunosorbent assay (LISA) for detecting antibodies against Treponema pallidum antigens TP0171 (TP15), TP0435 (TP17), and TP0574 (TP47) in diagnosing and monitoring syphilis. LISA for detection of anti-TP15, TP17, and TP47 antibodies were developed and evaluated for syphilis diagnosis using 261 serum samples (161 syphilis, 100 non-syphilis). Ninety serial serum samples from 6 syphilis rabbit models (3 treated, 3 untreated) and 110 paired serum samples from 55 syphilis patients were used to assess treatment effects by utilizing TRUST as a reference. Compared to TPPA, LISA-TP15, LISA-TP17, and LISA-TP47 showed a sensitivity of 91.9%, 96.9%, and 98.8%, specificity of 99%, 99%, and 98%, and AUC of 0.971, 0.992, and 0.995, respectively, in diagnosing syphilis. Strong correlations (rs = 0.89-0.93) with TPPA were observed. In serial serum samples from rabbit models, significant differences in the relative light unit (RLU) were observed between the treatment and control group for LISA-TP17 (days 31-51) and LISA-TP47 (day 41). In paired serum samples from syphilis patients, TRUST titres and the RLU of LISA-TP15, LISA-TP17, and LISA-TP47 decreased post-treatment (P < .001). When TRUST titres decreased by 0, 2, 4, or ≥8-folds, the RLU decreased by 17.53%, 31.34%, 48.62%, and 72.79% for LISA-TP15; 8.84%, 17.00%, 28.37%, and 50.57% for LISA-TP17; 22.25%, 29.79%, 51.75%, and 70.28% for LISA-TP47, respectively. Semi-quantitative LISA performs well for syphilis diagnosis while LISA-TP17 is more effective for monitoring syphilis treatment in rabbit models and clinical patients.

A novel syphilis Treponema pallidum lipoprotein peptide antigen diagnostic assay using red cell kodecytes in routine blood centre column agglutination testing platforms

BACKGROUND AND OBJECTIVES

The detection of treponemal antibodies, which are used to make a diagnosis of syphilis, is important both for diagnostic purposes and as a mandatory blood donor test in most countries. We evaluated the feasibility of using Kode Technology to make syphilis peptide red cell kodecytes for use in column agglutination serologic platforms.

MATERIALS AND METHODS

Candidate Kode Technology function-spacer-lipid (FSL) constructs were made for the Treponema pallidum lipoprotein (TmpA) of T. pallidum, using the peptide and FSL selection algorithms, and then used to make kodecytes. Developmental kodecytes were evaluated against a large range of syphilis antibody reactive and non-reactive samples in column agglutination platforms and compared against established methodologies. Overall, 150 reactive and 2072 non-reactive Syphicheck assay (a modified T. pallidum particle agglutination) blood donor samples were used to evaluate the agreement rate of the developed kodecyte assay.

RESULTS

From three FSL-peptide candidate constructs, one was found to be the most suitable for diagnostics. Of 150 Syphicheck assay reactive samples, 146 were TmpA-kodecyte reactive (97.3% agreement), compared with 58.0% with the rapid plasmin reagin (RPR) assay for the same samples. Against the 2072 expected syphilis non-reactive samples the agreement rate for TmpA-kodecytes was 98.8%.

CONCLUSION

TmpA-kodecytes are viable for use as cost-effective serologic reagent red cells for the detection of treponemal antibodies to diagnose syphilis with a high level of specificity in blood centres. This kodecyte methodology also potentially allows for introduction of the reverse-algorithm testing into low-volume laboratories, by utilizing existing transfusion laboratory infrastructure.

Refining a noninvasive prediction model for neurosyphilis diagnosis by using Immunoassay to Detect serum anti-TP0435 (TP17) and TP0574 (TP47) IgG antibodies: Two-center Cross-sectional retrospective study in China

OBJECTIVES

Invasive lumbar puncture (LP) is the conventional method for diagnosing neurosyphilis (NS). We investigated a noninvasive alternative method to detect serum Treponema pallidum specific antibodies against highly immunogenic antigens TP0171 (TP15), TP0435 (TP17), and TP0574 (TP47) by using luciferase immunosorbent assay (LISA).

METHODS

816 HIV-negative patients suspected of NS from Beijing and Guangzhou cohort were retrospectively selected and tested for serum anti-TP15, TP17, and TP47 IgG antibody. Two diagnostic prediction models were developed using stepwise logistic regression in Beijing cohort, and evaluated in Guangzhou cohort for external validation.

RESULTS

Serum antibodies against TP15, TP17, and TP47 showed moderate capability for NS diagnosis in Beijing cohort and the corresponding AUCs were 0.722 (95% CI: 0.680-0.762), 0.780 (95% CI: 0.741-0.817), and 0.774 (95% CI: 0.734-0.811), respectively. An expanded NS prediction model integrated with anti-TP17 and anti-TP47 antibodies showed better performance than the base NS diagnostic model without anti-TP17 and anti-TP47 antibodies with the AUC of 0.874 (95% CI: 0.841-0.906) vs 0.845 (95% CI: 0.809-0.881) (p = 0.007) in the development cohort, and 0.934 (95% CI: 0.909-0.960) vs 0.877 (95% CI: 0.840-0.914) (p<0.001) in validation cohort, respectively. Decision curve analysis (DCA) revealed that the net benefit of the expanded model exceeded that of the base model when the threshold probability was between 0.10 and 0.95 in both the development and external validation cohorts.

CONCLUSIONS

Serum antibodies against TP17 and TP47 exhibited promising diagnostic capability for NS and significantly enhanced predictive accuracy of model for NS diagnosis. Our study highlights the potential of serum treponemal antibody detection as a noninvasive method for NS diagnosis to substitute invasive LP in NS diagnosis.

Two-Stage Syphilis Testing

A 54-year-old woman presented with erythematous annular and indurated plaques on her face, trunk, and extremities and had false-positive syphilis test results during 2 pregnancies 25 and 22 years prior. What would you do next?

Performance Assessment of Treponemal and Nontreponemal Tests for the Diagnosis of Acquired Syphilis

There are a variety of nontreponemal test (NTT) and treponemal test (TT) kits for the serologic diagnosis of syphilis. Because of the complexity of the infection (multiple clinical stages) and the different antigens used in these kits, a systematic evaluation of the accuracy of the currently available commercial tests is warranted. Our objective was to evaluate the performance of commercially available tests for the diagnosis of syphilis infection. In this study, we analyzed one NTT (Venereal Disease Research Laboratory [VDRL] test, Wiener Laboratories, Rosario, Argentina) and two TTs (fluorescent treponemal antibody absorption [FTA-ABS] test, Euroimmun, Lübeck, Germany, and syphilis recombinant ELISA v. 4.0 test [ELISA], Wiener Laboratories, Rosario, Argentina) using a panel of 187 samples, including serum samples from 31 individuals with primary syphilis, 77 with secondary syphilis, and 79 with latent syphilis. An additional 192 samples from uninfected individuals and 323 serum samples from individuals with other diseases were included. The sensitivities of the VDRL, ELISA, and FTA-ABS tests were 97.9%, 100%, and 96.3%, respectively. The VDRL and ELISA tests showed a specificity of 100%, and the FTA-ABS test showed a specificity of 99.5%. Accuracy was 98.9% for the VDRL test, 100% for the ELISA, and 97.9% for the FTA-ABS test. For primary, secondary, and latent syphilis, the ELISA achieved a diagnostic performance of 100%, whereas the sensitivity for the VDRL and FTA-ABS tests ranged from 96.8% to 98.7% and 93.7% to 98.7%, respectively. No difference was observed when the tests were used as traditional or reverse algorithms. In general, all three tests are able to discriminate positive and negative samples for syphilis, regardless of the diagnostic algorithm.

State-of-the-Art Review: Neurosyphilis

We review key concepts in the diagnosis, treatment, and follow-up of individuals with neurosyphilis. We describe the epidemiology of syphilis in the United States, highlight populations that are markedly affected by this infection, and attempt to estimate the burden of neurosyphilis. We describe the cardinal clinical features of early and late (tertiary) neurosyphilis and characterize the clinical significance of asymptomatic neurosyphilis in the antibiotic era. We review the indications for cerebrospinal fluid (CSF) examination and the performance characteristics of different CSF assays including treponemal and lipoidal antibodies, white cell count, and protein concentration. Future biomarkers and the role of imaging are briefly considered. We review preferred and alternative treatments for neurosyphilis and evidence for their use, including evidence for the use of enhanced intramuscular benzathine penicillin G to supplement intravenous penicillin.

Serological follow-up after syphilis diagnosis in Israel

The global incidence of syphilis is increasing. Continuity of care challenges the control of sexually transmitted diseases. In this study, we assessed the follow-up and serological decline differences between community- and hospital-diagnosed patients in Israel. A historical cohort study was conducted using the Israel National Syphilis Center (NSC) repository. Patients with a positive non-specific Venereal Disease Research Laboratory (VDRL) test between 2011 and 2020 were included. Rates of serological follow-up and serological titre decreases were compared between hospital- and community-diagnosed patients. The study included 4,445 patients, 2,596 (58.4%) were diagnosed in community clinics and 1,849 (41.6%) in hospitals. Of community-diagnosed patients, 1,957 (75.4%) performed follow-up testing, compared with 834 (51.2%) hospital-diagnosed patients (p < 0.001). On multivariate analysis, the odds ratio of serology follow-up among community-diagnosed patients was 2.8 (95 per cent confidence interval (95% CI): 2.2-3.5) that of hospital-diagnosed patients. There were 1,397 (71.4%) community-diagnosed patients with serological titre decrease, compared with 626 (74.9%) hospital-diagnosed patients (p = 0.03). On multivariate analysis, this difference diminished. Serological follow-up testing is suboptimal and was performed more often among patients initially diagnosed in the community compared to hospitals. Continuity of care should be improved to promote successful patient care and prevent disease spread.

Syphilis Serologies: A Practical Approach for the Primary Care Clinician

Syphilis serology interpretation can be challenging even for experienced providers. This article reviews the staging of syphilis and the principles of syphilis serology testing, the algorithms used in diagnosis, and guidance for their use in monitoring the response to treatment. The authors illustrate these principles through a series of clinical scenarios and describe the rationale behind the management approaches.

Evaluating the diagnostic accuracy of TpN17 and TmpA recombinant proteins in syphilis detection: a phase II study

Syphilis is a sexually transmitted infection (STI) caused by the spiral bacterium Treponema pallidum. Diagnosis is based on epidemiology, clinical and serology, but serodiagnosis is challenging because distinct clinical forms of the infection may influence serological performance. Several recombinant Treponema pallidum-proteins have already been tested for syphilis diagnosis and they are critical to achieve high accuracy in serological testing. A total of 647 samples were included in the study: 180 T. pallidum-positive samples, 191 T. pallidum-negative samples and 276 sera from individuals infected with unrelated diseases. The diagnostic potential was validated by analysis of ROC curves. For the indirect ELISA, TpN17 (100%) and TmpA (99%) showed excellent AUC values. Sensitivity values were 97.2% for TpN17 and 90.6% for TmpA, while specificity was 100% for both molecules. According to the clinical phase, TmpA ranged from 84% to 97%, with the highest value for secondary syphilis. TpN17 was 100% sensitive for the primary and secondary stages and 93.2% for recent latent syphilis. All clinical phases achieved 100% specificity. Accuracy values showed that TmpA (> 95%) and TpN17 (> 98%) presented high diagnostic accuracy for all clinical stages of syphilis. Cross-reactivity was only observed in one sample positive for Chagas disease (1.5%), when TpN17 was evaluated. On the other hand, TmpA showed reactivity for two samples positive for Chagas disease (3.1%), one sample positive for HBV (1.25%), two samples positive for HIV (9.5%) and one sample positive for HTLV (1.6%). The TmpA antigen's performance was evaluated in multiple studies for syphilis diagnosis, corroborating our findings. However, TpN17 sensitivity values have ranged in other studies. According to clinical stages of the infection, our findings obtained close performance values.

CDC Laboratory Recommendations for Syphilis Testing, United States, 2024

This report provides new CDC recommendations for tests that can support a diagnosis of syphilis, including serologic testing and methods for the identification of the causative agent Treponema pallidum. These comprehensive recommendations are the first published by CDC on laboratory testing for syphilis, which has traditionally been based on serologic algorithms to detect a humoral immune response to T. pallidum. These tests can be divided into nontreponemal and treponemal tests depending on whether they detect antibodies that are broadly reactive to lipoidal antigens shared by both host and T. pallidum or antibodies specific to T. pallidum, respectively. Both types of tests must be used in conjunction to help distinguish between an untreated infection or a past infection that has been successfully treated. Newer serologic tests allow for laboratory automation but must be used in an algorithm, which also can involve older manual serologic tests. Direct detection of T. pallidum continues to evolve from microscopic examination of material from lesions for visualization of T. pallidum to molecular detection of the organism. Limited point-of-care tests for syphilis are available in the United States; increased availability of point-of-care tests that are sensitive and specific could facilitate expansion of screening programs and reduce the time from test result to treatment. These recommendations are intended for use by clinical laboratory directors, laboratory staff, clinicians, and disease control personnel who must choose among the multiple available testing methods, establish standard operating procedures for collecting and processing specimens, interpret test results for laboratory reporting, and counsel and treat patients. Future revisions to these recommendations will be based on new research or technologic advancements for syphilis clinical laboratory science.

A 4-fold or greater decrease in TPPA titers may indicate effective BPG treatment in primary syphilis

BACKGROUND

In the majority of clinical environments, the treponema pallidum particle agglutination (TPPA) test is known for its higher specificity compared to the rapid plasma reagin (RPR) test and is commonly employed for the diagnosis of syphilis, but their use for serological monitoring after syphilis therapy is controversial.

OBJECTIVES

We aim to evaluate whether the TPPA titers is suitable for monitoring syphilis treatment efficacy.

METHODS

At first, 232 patients with primary syphilis were recruited. Serological testing was performed at baseline (initial visit) and at 6 months (±1 month) after benzathine penicillin G (BPG) treatment. Second, New Zealand white male rabbits were infected with Treponema pallidum (T. pallidum) to evaluate the changes in TPPA titers after BPG therapy. Finally, we compared the TPPA titers in the culture supernatant of rabbit splenocytes stimulated with T. pallidum with or without BPG.

RESULTS

After 6 months of treatment, 150 (64.7%) of 232 primary syphilis patients achieved serological cure, and 82 (35.3%) had adverse outcomes. Among 110 patients with TPPA titers decreased by more than fourfold, 109 of them were serological cure patients (≥4-fold decrease in RPR titers) (P ＜ 0.0001). In the rabbit model of syphilis, the TPPA titers was significantly decreased in the treatment subgroup (P = 0.016) and remained constant (±2-fold) or increased (≥4-fold) in the nontreatment subgroup. In addition, T. pallidum resulted in a positive TPPA titers in the culture supernatant of splenocytes (median titers was 1: 80), while BPG could directly reduce the TPPA titers in the culture supernatant (median titers was 1: 40) (P = 0.032).

CONCLUSIONS

A 4-fold or greater decrease in TPPA titers may indicate effective treatment in primary syphilis. Combining TPPA titers with RPR titers results may potentially aid in the early diagnosis of syphilis.

Evaluation of a minimal array of Treponema pallidum antigens as biomarkers for syphilis diagnosis, infection staging, and response to treatment

IMPORTANCE

This manuscript explores the host humoral response to selected antigens of the syphilis agent during infection to evaluate their potential use as diagnostic tests and markers for treatment.

Primary syphilis, an extremely uncommon cause of acute-onset phimosis

We present a case of phimosis in the context of primary syphilis with a preputial chancre. An accurate diagnosis after an appropriate examination and patient history allowed conservative treatment with antibiotics and the avoidance of circumcision in this patient.

Treponema pallidum Detection at Asymptomatic Oral, Anal, and Vaginal Sites in Adults Reporting Sexual Contact with Persons with Syphilis

We investigated Treponema pallidum PCR positivity at mucosal sites (oral, anal, and vaginal sites) among adults who had sexual contact with a person with syphilis (syphilis contacts). All syphilis contacts had oral rinse and swab samples collected for testing. Men who have sex with men had anal swab and women had vaginal swab samples collected for testing, regardless of the presence of lesions. Of 407 persons tested, 42 (10%) had early syphilis diagnosed; of those, 19 (45%) tested positive by PCR from any anatomic site and had a positive serologic test. T. pallidum was positive from vaginal samples in 3 women, anal samples in 3 men, and oral cavity samples in 2 women and 3 men, without symptoms at those sites. Three women had no prior syphilis serologic test. T. pallidum detection at asymptomatic mucosal sites suggests early syphilis infections, particularly in cases that would conventionally be staged as latent syphilis of unknown duration.

Penicillin Responsive Presumed Seronegative Ocular Syphilis in a Patient with Human Immunodeficiency Virus: A Case Report and Review of the Literature

Ocular and systemic syphilis are well known to mimic other clinical entities making them challenging to diagnose in many cases. Syphilis testing plays an important role in diagnosis and timely treatment. Here we describe a patient with untreated human immunodeficiency virus (HIV) infection who presented with bilateral panuveitis with repeatedly negative syphilis serologies. In light of worsening retinitis while on aggressive anti-viral treatment and in consideration of the clinical suspicion for syphilitic uveitis, intravenous penicillin was initiated empirically. The patient demonstrated significant improvement subjectively and objectively after treatment. We also review and discuss syphilis testing reliability generally and in HIV co-infected patients in particular. Empiric intravenous penicillin should be considered in patients with clinical features of ocular syphilis despite negative serologic testing, especially in those with HIV co-infection.

The Diagnostic Performance of Laboratory Tests of Neurosyphilis: A Systematic Review and Network Meta-Analysis

INTRODUCTION

The gold standard for diagnosing neurosyphilis (NS) is currently unavailable; various laboratory parameters in cerebrospinal fluid (CSF) and blood can assist in the diagnosis.

METHODS

PubMed, Embase, and the Cochrane Library were searched. Studies utilizing laboratory tests to assist in the diagnosis of NS were included. The pooled indicators for diagnostic performance and their respective 95% confidence intervals (CIs) were calculated. We used the superiority index to test the superiority of a diagnostic test.

RESULTS

Eleven citations were included in the study. Albumin quotient, CSF-TPHA, CSF-EIA, CSF-LDH, CSF-WBC, CSF-CXCL13, FTA-ABS, CSF-PCR, RPR, CSF-TPPA, TRUST, and CSF-venereal diseases research laboratory (VDRL) were assessed in the studies included. The pooled estimates of sensitivity, specificity, AUC of SROC and their respective 95% CIs for CSF-TPPA and CSF-VDRL were 0.97 (0.17, 1.00), 0.84 (0.62, 0.95), 0.93 (0.91, 0.95) and 0.74 (0.59, 0.85), 0.99 (0.93, 1.00), 0.94 (0.91, 0.96), respectively. CSF-TPHA demonstrated the highest relative sensitivity. CSF-VDRL manifested the highest specificity. CSF-TPHA, TRUST, CSF-VDRL, CSF-EIA, and RPR ranked in the top five laboratory tests with superiority index.

CONCLUSION

CSF-TPHA, TRUST, CSF-VDRL, CSF-EIA, and RPR indicate acceptable performance in detecting NS compared to other modalities. Comprehensive diagnostic strategies still play a significant role in the diagnosis of NS.

Advantages and limitations of current diagnostic laboratory approaches in syphilis and congenital syphilis

INTRODUCTION

The reemergence of syphilis, especially congenital syphilis, presents a significant public health threat. Accurate diagnosis of syphilis depends on recognition of a constellation of symptoms, review of medical and sexual history, and multiple laboratory tests. While reliable, current tests for syphilis can be difficult to interpret, which can lead to delays in treatment.

AREA COVERED

This review summarizes the major advantages and limitations of available diagnostic laboratory methods for syphilis, provides an update on recent advances in laboratory tools, and highlights the urgent need for coordinated efforts to create new tools to halt the resurgence of syphilis.

EXPERT OPINION

In syphilis, the wide variety of short-lived signs and symptoms followed by periods of latency create diagnostic challenges. Currently available laboratory tests, when positive, require additional information to interpret (prior testing, treatment, and sexual history). Point-of-care tests that can rapidly and accurately detect both treponemal and non-treponemal antibodies would be a huge step toward reducing test turnaround time and time to treatment. Incorporating biological insights and technology innovations to advance the development of direct detection assays is urgently needed. A comprehensive coordinated effort is critical to stem the tide of rising syphilis in the United States and globally.

Syphilis

Syphilis is an important public health problem in the U.S. and many high-income nations. The rates of syphilis continue to increase and there is an urgent need for medical providers of a variety of backgrounds to recognize this disease. In this review, we cover the key clinical findings of syphilis and provide an overview of the diagnosis and management of this disease in adults.

Performance of the nontreponemal tests and treponemal tests on cerebrospinal fluid for the diagnosis of neurosyphilis: A meta-analysis

Background

Nontreponemal and treponemal tests for analyzing cerebrospinal fluid to confirm the existence of neurosyphilis have been widely used, so we aim to evaluate and compare their performance on the cerebrospinal fluid in the diagnosis of neurosyphilis.

Methods

We conducted a systematic literature search on five databases and utilized a bivariate random-effects model to perform the quantitative synthesis.

Results

Nontreponemal tests demonstrated a pooled sensitivity of 0.77 (95% CI: 0.68-0.83), a pooled specificity of 0.99 (95% CI: 0.97-1.00), and a summary AUC of 0.97 (95% CI: 0.95-0.98). The pooled sensitivity, pooled specificity, and summary AUC of treponemal tests were 0.95 (95% CI: 0.90-0.98), 0.85 (95% CI: 0.67-0.94), and 0.97 (95% CI: 0.95-0.98), respectively. The pooled specificity of all nontreponemal tests varied minimally (ranging from 0.97 to 0.99), with TRUST (0.83) having a higher pooled sensitivity than VDRL (0.77) and RPR (0.73). Among all treponemal tests, EIA has outstanding diagnostic performance with a pooled sensitivity of 0.99 and a pooled specificity of 0.98.

Conclusion

Nontreponemal tests exhibited a higher pooled specificity, and treponemal tests exhibited a higher pooled sensitivity in diagnosing neurosyphilis on cerebrospinal fluid. TRUST may be a satisfactory substitute for VDRL. EIA is a prospective diagnostic tool that deserves further study in the future. Our study may be useful to clinical laboratories in selecting appropriate serological tests on the cerebrospinal fluid for the diagnosis of neurosyphilis.

Evaluation of cerebrospinal fluid ubiquitin C-terminal hydrolase-L1, glial fibrillary acidic protein, and neurofilament light protein as novel markers for the diagnosis of neurosyphilis among HIV-negative patients

OBJECTIVES

To evaluate the possibility of using cerebrospinal fluid (CSF) ubiquitin C-terminal hydrolase L1 (UCH-L1), glial fibrillary acidic protein (GFAP), and neurofilament light protein (NF-L) for the diagnosis of neurosyphilis (NS).

METHODS

A cross-sectional study of 576 subjects was conducted at Zhongshan Hospital from January 2021 to August 2022 to evaluate the diagnostic accuracy of CSF UCH-L1, GFAP, and NF-L for NS and analyze their correlations with CSF rapid plasma reagin (RPR), white blood cells (WBCs), and protein.

RESULTS

Patients with NS had higher CSF UCH-L1, GFAP, and NF-L levels than patients with syphilis/non-NS and nonsyphilis. Using a cut-off point of 652.25 pg/ml, 548.89 pg/ml, and 48.38 pg/ml, CSF UCH-L1, GFAP, and NF-L had a sensitivity of 85.11%, 76.60%, and 82.98%, with a specificity of 92.22%, 85.56%, and 91.11%, respectively, for NS diagnosis. Moreover, parallel and serial testing algorithms improved their sensitivity and specificity to 93.62% and 98.89%, respectively. Interestingly, levels between patients with NS who are CSF RPR-positive and -negative did not differ and showed a weak or moderate correlation with WBC and CSF protein in patients with syphilis.

CONCLUSION

CSF UCH-L1, GFAP, and NF-L can be used as novel markers for the diagnosis of NS, independent of CSF RPR, WBC, and proteins.

CARE-NS, a research strategy for neurosyphilis

Neurosyphilis is a major clinical manifestation of syphilis. In recent years, an increase in neurosyphilis cases has been reported in many countries. The overall incidence of neurosyphilis remains unknown, and there is a lack of understanding of the disease pathogenesis, which hampers clinical management, development of prevention strategies, and control. This article proposes the CARE-NS research strategy to enhance the clinical management of neurosyphilis, which consists of six key features: comprehensive management including multidisciplinary treatment (C), alleviating neurological impairment and sequelae (A), risk factors and clinical epidemiology (R), etiology and pathogenesis (E), new diagnostic indicators and strategies (N), and social impact and cost-effectiveness analysis (S).

A Young Man Presenting With Tongue Lesions

A 19-year-old man presented with tongue pain of 3 months’ duration and a raised tongue lesion with slightly hairy appearance. What is your diagnosis?

Analysis of Treponema pallidum DNA and CXCL13 in Cerebrospinal Fluid in HIV-Negative Syphilis Patients

Purpose

Neurosyphilis (NS) is a chronic infectious disease associated with Treponema pallidum subsp. pallidum (TP) infection of the central nervous system. The purpose of this study was to offer evidence for the diagnosis and treatment of NS by revealing the detection of TP DNA and CXCL13 concentration in the cerebrospinal fluid (CSF) of HIV-negative syphilis patients.

Patients and Methods

This study included 75 syphilis patients. The frequency of TP invasion into the CSF was detected by nested PCR. ELISA was performed to detect CSF CXCL13 concentrations, and ROC analysis was performed to assess diagnostic accuracy. Sociodemographic data, clinical symptoms, and laboratory indices of patients were collected. CSF CXCL13 levels and clinical characteristics of syphilis patients were investigated retrospectively.

Results

The detection rate of CSF DNA of TP by nested PCR was 5.3% and 16.7% in HIV-negative syphilis patients and NS patients, respectively. There was a significant difference between the NS and non-NS groups in terms of neurological symptoms, CSF TPPA, CSF TRUST, CSF nucleated cells, CSF protein, and CSF CXCL13 levels (P<0.05). ROC curve analysis showed that the AUC for CSF CXCL13 levels was 0.906 (95% CI 0.832-0.981, P <0.0001), with an optimal critical value of 57.85 pg/mL and sensitivity and specificity of 88.89% and 78.95%, respectively.

Conclusion

Nested PCR can be used as an auxiliary diagnosis of NS, and CSF CXCL13 >60 pg/mL has high sensitivity and specificity for NS patients and non-NS patients. CXCL13 may be a useful marker to distinguish NS from non-NS syphilis in HIV-negative patients.

Advances in laboratory diagnostic methods for cerebrospinal fluid testing for neurosyphilis

Neurosyphilis is a chronic infectious disease caused by the invasion of Treponema pallidum into the central nervous system. In recent years, with the increase in the latent syphilis infection rate, the incidence of neurosyphilis has gradually increased, the typical symptoms of neurosyphilis have decreased, atypical manifestations have increased, and the clinical manifestations have become increasingly diverse. Cerebrospinal fluid testing plays an important role in the diagnosis of neurosyphilis. In recent years, there have been many advances in cerebrospinal fluid testing. This review focuses on the current and potential laboratory indicators of neurosyphilis in cerebrospinal fluid, aiming to provide a reference for clinical application and ideas for future experimental research of neurosyphilis.

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.

Congenital Syphilis Presenting with Brain Abnormalities at Neuroscan: A Case Report and a Brief Literature Review

A case of vertical transmission in a 35-year-old pregnant woman, gravida 4, para 2 with an unknown medical history of carrying primary syphilis is described. A routine 3rd trimester scan was performed at 30 + 5 weeks of pregnancy, which revealed fetal growth restriction (FGR) associated with absent fetal movement, a pathologic neuroscan characterized by cortical calcifications and ominous Doppler waveform analysis of the umbilical artery and ductus venosus. Computerized electronic fetal monitoring (EFM) showed a Class III tracing, according to the American College of Obstetricians and Gynecologists (ACOG) guidelines. An emergency C-section was performed and a female newborn weighing 1470 g was delivered. The Apgar scores were 5 and 8 at the first and fifth min, respectively. Besides the prompted obstetrical and neonatal interventions, the neonate died after 7 days. A histologic examination of the placenta revealed a chorioamnionitis at stage 1/2 and grade 2/3. The parenchyma showed diffuse delayed villous maturation, focal infarcts, and intraparenchymal hemorrhages. The decidua presented with chronic deciduitis with plasma cells. The parents declined the autopsy. Congenital syphilis is an emerging worldwide phenomenon and the multidisciplinary management of the mother and the fetus should be mandatory.

Point-of-Care Diagnostics for Diagnosis of Active Syphilis Infection: Needs, Challenges and the Way Forward

Syphilis, a curable sexually transmitted infection, has re-emerged as a global public health threat with an estimated 5.6 million new cases every year. Pregnant women and men who have sex with men are key target populations for syphilis control and prevention programs. Frequent syphilis testing for timely and accurate diagnosis of active infections for appropriate clinical management is a key strategy to effectively prevent disease transmission. However, there are persistent challenges in the diagnostic landscape and service delivery/testing models that hinder global syphilis control efforts. In this commentary, we summarise the current trends and challenges in diagnosis of active syphilis infection and identify the data gaps and key areas for research and development of novel point-of-care diagnostics which could help to overcome the present technological, individual and structural barriers in access to syphilis testing. We present expert opinion on future research which will be required to accelerate the validation and implementation of new point-of-care diagnostics in real-world settings.

Neurosyphilis in China: A Systematic Review of Cases From 2009-2021

Considered the increased threaten of neurosyphilis in China, a review on cases reported in the literature to describe the clinical epidemiological characteristics of neurosyphilis cases, may be beneficial to the early detection and management strategies of neurosyphilis for clinicians. We searched the literature on Chinese neurosyphilis cases published from January 1, 2009 to December 31, 2021, described their clinical epidemiological characteristics and calculated the prevalence of neurosyphilis amongst other associated diseases, according to the individual study criteria. A total of 284 studies including 7,486 neurosyphilis cases were included. No meta-analysis was performed due to the heterogeneity of the data. Among 149 case reports and 93 retrospective case series studies, the main clinical manifestation of 3,507 neurosyphilis cases was cerebral parenchymal syphilis (57.3%), followed by asymptomatic neurosyphilis (16.7%), meningovascular syphilis (13.6%), meningitis syphilis (7.7%) and ocular syphilis (2.8%), etc. In addition, the initial diagnosis was incorrect in 53.2% patients, and the most frequent misdiagnoses were mental disorders (31.0%), stroke (15.9%), cognitive impairment (9.0%), etc. The positive or abnormal rates of cerebrospinal fluid non-treponemal and treponemal tests, white blood cell counts and protein concentrations were 74.2%, 96.2%, 61.5%, and 60.9%, respectively. Aqueous penicillin was the first choice for treatment in 88.3% cases, and 81.7% and 50.0% patients had response in the improvement of symptoms and serological effective in CSF, respectively. Among 26 studies on neurosyphilis patients amongst other associated diseases, the prevalence of neurosyphilis amongst central nervous system infectious diseases, syphilis-associated neurological symptoms, serofast status, coinfected with human immunodeficiency virus were 10.6%-30.1%, 23.2%-35.5%, 9.8%-56.1%, and 8.9%, respectively. In summary, the lack of early detection of neurosyphilis cases remains a clinical challenge. The high rate of misdiagnosis and high prevalence of neurosyphilis amongst associated diseases strongly remind clinicians to focus on the early detection among suspected cases. Besides, the standard treatment regimen and long-term follow-up, which complied with guideline should be provided. Further prospective studies are urgent to better delineate the clinical epidemiological characteristics of neurosyphilis in China.

Diagnosis and Treatment of Sexually Transmitted Infections: A Review

IMPORTANCE

Approximately 1 in 5 adults in the US had a sexually transmitted infection (STI) in 2018. This review provides an update on the epidemiology, diagnosis, and treatment of gonorrhea, chlamydia, syphilis, Mycoplasma genitalium, trichomoniasis, and genital herpes.

OBSERVATIONS

From 2015 to 2019, the rates of gonorrhea, chlamydia, and syphilis increased in the US; from 1999 to 2016, while the rates of herpes simplex virus type 1 (HSV-1) and HSV-2 declined. Populations with higher rates of STIs include people younger than 25 years, sexual and gender minorities such as men and transgender women who have sex with men, and racial and ethnic minorities such as Black and Latinx people. Approximately 70% of infections with HSV and trichomoniasis and 53% to 100% of extragenital gonorrhea and chlamydia infections are asymptomatic or associated with few symptoms. STIs are associated with HIV acquisition and transmission and are the leading cause of tubal factor infertility in women. Nucleic acid amplification tests have high sensitivities (86.1%-100%) and specificities (97.1%-100%) for the diagnosis of gonorrhea, chlamydia, M genitalium, trichomoniasis, and symptomatic HSV-1 and HSV-2. Serology remains the recommended method to diagnose syphilis, typically using sequential testing to detect treponemal and nontreponemal (antiphospholipid) antibodies. Ceftriaxone, doxycycline, penicillin, moxifloxacin, and the nitroimidazoles, such as metronidazole, are effective treatments for gonorrhea, chlamydia, syphilis, M genitalium, and trichomoniasis, respectively, but antimicrobial resistance limits oral treatment options for gonorrhea and M genitalium. No cure is available for genital herpes. Effective STI prevention interventions include screening, contact tracing of sexual partners, and promoting effective barrier contraception.

CONCLUSIONS AND RELEVANCE

Approximately 1 in 5 adults in the US had an STI in 2018. Rates of gonorrhea, chlamydia, and syphilis in the US have increased, while rates of HSV-1 and HSV-2 have declined. Ceftriaxone, doxycycline, penicillin, moxifloxacin, and the nitroimidazoles are effective treatments for gonorrhea, chlamydia, syphilis, Mycoplasma genitalium, and trichomoniasis, respectively, but antimicrobial resistance limits oral therapies for gonorrhea and Mycoplasma genitalium, and no cure is available for genital herpes.

[Syphilis in young Brazilian military recruits in 2016: sociodemographic, behavioral, and clinical aspects]

The objective was to characterize sociodemographic, behavioral, and clinical aspects in young Brazilian military recruits according to prevalence of syphilis. This was a descriptive study based on a nationwide population-based survey in 2016 with a probabilistic sample of military recruits 17 to 22 years of age. A confidential self-applied questionnaire was used. Blood samples were drawn from participants for treponemal and non-treponemal syphilis tests. Descriptive statistical techniques were used to estimate syphilis prevalence rates and distribution of frequencies between the target variables, considering 95% confidence intervals (95%CI), after weighting the data. Of the total of 37,282 participants, 73.7% were sexually initiated. Prevalence rates for lifetime and confirmed syphilis were 1.6% and 1.1%, respectively. The following population variables showed higher prevalence of syphilis: lack of Internet access at home; initiation of sexual activity before 14 years of age; men who have sex with men; more than five sexual partners; having received presents, drugs, or other incentives in exchange for sex; and prior history of symptoms of sexually transmissible infections. An increase was observed in syphilis in Brazilian military recruits when compared to previous surveys. This increase emphasizes the importance of this sentinel population for performing active surveillance in order to support healthcare strategies for youth, including in the school system.

Sexually Transmitted Infections Treatment Guidelines, 2021

These guidelines for the treatment of persons who have or are at risk for sexually transmitted infections (STIs) were updated by CDC after consultation with professionals knowledgeable in the field of STIs who met in Atlanta, Georgia, June 11–14, 2019. The information in this report updates the 2015 guidelines. These guidelines discuss 1) updated recommendations for treatment of Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis; 2) addition of metronidazole to the recommended treatment regimen for pelvic inflammatory disease; 3) alternative treatment options for bacterial vaginosis; 4) management of Mycoplasma genitalium; 5) human papillomavirus vaccine recommendations and counseling messages; 6) expanded risk factors for syphilis testing among pregnant women; 7) one-time testing for hepatitis C infection; 8) evaluation of men who have sex with men after sexual assault; and 9) two-step testing for serologic diagnosis of genital herpes simplex virus. Physicians and other health care providers can use these guidelines to assist in prevention and treatment of STIs.

Syphilis Diagnosis and Treatment: State of The Art

The present review summarises the current knowledge in the field of syphilis diagnosis and treatment, along with epidemiologic and historical data. A literature search was conducted in PubMed and Google Scholar, using the search terms “syphilis”, “diagnosis”, “dermoscopy”, “management AND treatment”, “laboratory tests AND syphilis”, and “primary OR secondary OR tertiary OR congenital syphilis”. A total of 55 out of 100 papers were included in this review. An overview of the different clinical presentation of primary, secondary, tertiary, and congenital syphilis, with particular attention to dermatologic signs and dermoscopic examination, is provided. The panorama diagnostic procedures are illustrated, along with their accuracy and recommendation. Treatment and management options of patients at different syphilis stages are provided and discussed according to the referring guidelines. The dermatologist can play a key role in providing the early and correct diagnosis and setting up in the proper management of patients with syphilis infection.

Neurosyphilis and Lyme neuroborreliosis

PURPOSE OF REVIEW

Neurosyphilis (NS) and Lyme neuroborreliosis (LNB) are spirochetal diseases with distinct clinical manifestations. The diagnosis of NS remains challenging due to imperfect diagnostic criteria and testing modalities. With LNB, misconceptions about diagnosis and treatment lead to considerable morbidity and drug related adverse effects.

RECENT FINDINGS

Although studies continue investigating alternate approaches and new diagnostic tests for NS, few data exist to change current approaches to diagnosis, management or follow up. In the diagnosis of LNB, the chemokine CXCL13 shows promising diagnostic accuracy. A systematic review discourages the use of cell-based assays when investigating Lyme disease. Clinical studies show no benefit from extended antibiotic treatment for patients with unspecific symptoms labelled as having Lyme disease.

SUMMARY

The diagnosis of NS may be delayed due to a lack of specificity of findings, low suspicion for syphilis, and/or similarities in presentation to other diseases. A high index of suspicion for syphilis is required provide timely diagnosis and management of NS. Fortunately, penicillin remains the treatment of choice. Overdiagnosis and overtreatment in patients labelled as having Lyme disease can be avoided by an evidence-based approach towards diagnosis and treatment.

Syphilitic Aortic Aneurysm: A Rare Entity in the Era of Antibiotics

A thoracic aortic aneurysm is a rare entity of tertiary syphilis in the era of antibiotics. The diagnosis of the aortic aneurysm due to tertiary syphilis may be challenging due to deceptive clinical presentation and rarity of the disease in the western world. We report the case of a 59-year-old man, who presents with worsening shortness of breath and was found to have a large ascending aortic aneurysm on computed tomography angiogram (CTA) of the chest. Further workup demonstrated a positive syphilis test. Untreated earlier stages of syphilis attribute to the development of the ascending aortic aneurysm. The patient was medically treated with IV penicillin and underwent surgical repair of the aortic aneurysm. Histopathology confirmed the diagnosis of syphilitic aortitis. Tertiary syphilis often presents several years after initial infection and usually after a latent phase, making it difficult to diagnose. Syphilitic aortic aneurysms may result in a high mortality rate in untreated patients. Therefore, a high index of suspicion is required for the early recognition of a syphilitic aortic aneurysm. Early treatment with antibiotic therapy and surgical repair of syphilitic aortic aneurysms can prevent life-threatening complications.

Rational laboratory testing in uveitis: A Bayesian analysis

Uveitis encompasses a heterogeneous group of clinical entities with the common feature of intraocular inflammation. In addition to patient history and examination, a focused set of laboratory investigations is frequently necessary to establish a specific diagnosis. There is limited consensus among uveitis specialists regarding appropriate laboratory evaluation for many distinct patient presentations. The appropriateness of a laboratory test for a given case of uveitis will depend on patient-specific as well as epidemiologic factors. Bayesian analysis is a widely used framework for the interpretation of laboratory testing, but is seldom adhered to in clinical practice. Bayes theorem states that the predictive value of a particular laboratory test depends on the sensitivity and specificity of that test, as well as the prevalence of disease in the population being tested. In this review we will summarize the performance of commonly-utilized laboratory tests for uveitis, as well as the prevalence of uveitic diagnoses in different geographic practice settings. We will propose a logical framework for effective laboratory testing in uveitic disease through rigorous application of Bayesian analysis. Finally, we will demonstrate that while many highly sensitive laboratory tests offer an effective means to rule out associated systemic disease, limited test specificity and low pretest probability often preclude the diagnosis of systemic disease association with any high degree of certainty, even in the face of positive testing.

Laboratory Diagnostic Tools for Syphilis: Current Status and Future Prospects

With the increasing number of patients infected with syphilis in the past 20 years, early diagnosis and early treatment are essential to decline syphilis prevalence. Owing to its diverse manifestations, which may occur in other infections, the disease often makes clinicians confused. Therefore, a sensitive method for detecting T. pallidum is fundamental for the prompt diagnosis of syphilis. Morphological observation, immunohistochemical assay, rabbit infectivity test, serologic tests, and nucleic acid amplification assays have been applied to the diagnosis of syphilis. Morphological observation, including dark-field microscopy, silver-staining, and direct fluorescent antibody staining for T. pallidum, can be used as a direct detection method for chancre specimens in primary syphilis. Immunohistochemistry is a highly sensitive and specific assay, especially in the lesion biopsies from secondary syphilis. Rabbit infectivity test is considered as a sensitive and reliable method for detecting T. pallidum in clinical samples and used as a historical standard for the diagnosis of syphilis. Serologic tests for syphilis are widely adopted using non-treponemal or treponemal tests by either the traditional or reverse algorithm and remain the gold standard in the diagnosis of syphilis patients. In addition, nucleic acid amplification assay is capable of detecting T. pallidum DNA in the samples from patients with syphilis. Notably, PCR is probably a promising method but remains to be further improved. All of the methods mentioned above play important roles in various stages of syphilis. This review aims to provide a summary of the performance characteristics of detection methods for syphilis.