Evaluation of treponemal serum tests performed on cerebrospinal fluid for diagnosis of neurosyphilis

LC-MS metabolomics and lipidomics in cerebrospinal fluid from viral and bacterial CNS infections: a review

There is compelling evidence that a dysregulated immune inflammatory response in neuroinfectious diseases results in modifications in metabolic processes and altered metabolites, directly or indirectly influencing lipid metabolism within the central nervous system (CNS). The challenges in differential diagnosis and the provision of effective treatment in many neuroinfectious diseases are, in part, due to limited understanding of the pathophysiology underlying the disease. Although there are numerous metabolomics studies, there remains a deficit in neurolipidomics research to provide a comprehensive understanding of the connection between altered metabolites and changes in lipid metabolism. The brain is an inherently high-lipid organ; hence, understanding neurolipidomics is the key to future breakthroughs. This review aims to provide an integrative summary of altered cerebrospinal fluid (CSF) metabolites associated with neurolipid metabolism in bacterial and viral CNS infections, with a particular focus on studies that used liquid chromatography-mass spectrometry (LC-MS). Lipid components (phospholipids) and metabolites (carnitine and tryptophan) appear to be the most significant indicators in both bacterial and viral infections. On the basis of our analysis of the literature, we recommend employing neurolipidomics in conjunction with existing neurometabolomics data as a prospective method to enhance our understanding of the cross link between dysregulated metabolites and lipid metabolism in neuroinfectious diseases.

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.

Cerebrospinal Fluid Biomarkers of Symptomatic Neurosyphilis in People With HIV Compared with Uninfected Individuals

We evaluated the diagnostic clinical performance characteristics (DCPC) of cerebrospinal fluid (CSF) total protein (TP), white blood cell count (WBC), and lactate (LA) with different cutoff points as adjunct biomarkers of confirmed or presumptive symptomatic neurosyphilis (NS) and the impact of HIV infection. From 5,640 participants who underwent lumbar punctures, 236 participants were included, and classified as either people with HIV (PWH) or people without HIV (PWoH) according to the CDC criteria for confirmed NS (n = 42), presumptive NS (n = 74), systemic syphilis (SS) (n = 38), serological diagnosis of syphilis (n = 18), PWH without SS and NS (n = 10), and negative control (n = 72). In PWoH, for presumptive NS, the combination of CSF TP > 45 mg/dL and/or WBC > 5.0 cells/mm3 is valuable for screening, whereas in PWH, it is not recommended for either screening or case-finding NS, however the DCPC were better in the suppressed group. In PWoH, the value of CSF TP > 45 mg/dL is adequate for both screening and confirmation of presumptive NS, subject to prevalence. For WBC count > 20 cell/mm3, the positive predictive value (PPV) of the test is almost perfect, suggesting a confirmatory test. In PWH, CSF TP is an inadequate marker of NS. The WBC count, with cutoffs of > 10 or > 20 cells/mm3, was moderately applicable for screening.As conclusions: CSF WBC count and TP showed distinct DCPC in confirmed or presumptive NS, better in the former. These biomarkers could be included for presumptive NS diagnosis. DCPC of these biomarkers for the diagnosis of NS is greatly affected by HIV co-infection.

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.

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.

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.

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.

Management of Adult Syphilis: Key Questions to Inform the 2021 Centers for Disease Control and Prevention Sexually Transmitted Infections Treatment Guidelines

A panel of experts generated 5 "key questions" in the management of adult syphilis. A systematic literature review was conducted and tables of evidence were constructed to answer these questions. Available data suggest no clinical benefit to >1 dose of benzathine penicillin G for early syphilis in human immunodeficiency virus (HIV)-infected patients. While penicillin remains the drug of choice to treat syphilis, doxycycline to treat early and late latent syphilis is an acceptable alternate option if penicillin cannot be used. There are very limited data regarding the impact of additional antibiotic doses on serologic responses in serofast patients and no data on the impact of additional antibiotic courses on long-term clinical outcomes. In patients with isolated ocular or otic signs and symptoms, reactive syphilis serologic results, and confirmed ocular/otic abnormalities at examination, a diagnostic cerebrospinal fluid (CSF) examination is not necessary, because up to 40% and 90% of patients, respectively, would have no CSF abnormalities. Based on the results of 2 studies, repeated CSF examinations are not necessary for HIV-uninfected patients or HIV-infected patients on antiretroviral therapy who exhibit appropriate serologic and clinical responses after treatment for neurosyphilis. Finally, several important gaps were identified and should be a priority for future research.

Acute syphilitic posterior placoid chorioretinitis: when the great mimicker cannot pretend any more; new insight of an old acquaintance

Purpose

To review the multimodal imaging patterns of Acute Syphilitic Posterior Placoid Chorioretinitis (ASPPC).

Methods

A systematic review.

Results

Syphilis has started to attract the attention of researchers once again due to recent surges, with The World Health Organization (WHO) reporting around 12 million new cases per year. When left untreated, syphilis has a mortality rate of 8–58%, with a higher death rate in males. Eye manifestations occur both in secondary and tertiary stages of syphilis, although ocular involvement may occur at any stage of the disease.

Syphilis has been always recognized as “the great mimicker” since it can have multiple clinical patterns of presentation.

However, Acute Syphilitic Posterior Placoid Chorioretinitis (ASPPC) represents the typical pattern of the disease and can be easily distinguished.

In addition, the advent of modern technologies and the progress made in multimodal imaging have provided more details on its identikit: the pattern of pre-retinal, retinal, retinochoroidal and optic nerve involvement can be identified before going through the laboratory work-up for a correct and appropriate investigation of the disease.

Conclusion

This review highlights the peculiar pattern of ASPPC, by reporting the diagnostic process made by all the imaging techniques used for a correct multimodal imaging assessment.

Intrathecal Synthesis Index of Specific Anti-Treponema IgG: a New Tool for the Diagnosis of Neurosyphilis

Neurosyphilis (NS) diagnosis is challenging because clinical signs are diverse and unspecific, and a sensitive and specific laboratory test is lacking. We tested the performance of an antibody index (AI) for intrathecal synthesis of specific anti-Treponema IgG by enzyme-linked immunosorbent assay (ELISA) for NS diagnosis. We conducted a retroprospective monocentric study including adults with neurological symptoms who had serum and cerebral spinal fluid (CSF) samples collected between 2006 and 2021. Two NS definitions were used. NS1 included patients with neurological symptoms, positive Treponema pallidum particle agglutination (TPPA) serology, and CSF-TPPA of ≥320, as well as CSF-leukocytes of >5 cells/mm³ and/or CSF-protein of >0.45 g/L and/or a reactive CSF-VDRL/RPR test. NS2 included patients with acute ocular and/or otologic symptoms, positive TPPA serology, and a response to NS treatment. Controls were patients with central nervous system disorders other than neurosyphilis. Anti-Treponema pallidum IgG were measured simultaneously in serum and CSF, and AI was calculated according to Reiber diagram. We assessed the AI test area under the curve (AUC), sensitivity/specificity, and estimated positive and negative predictive values. In total, 16 NS1 patients, 11 NS2 patients, and 71 controls were included. With an AI of ≥1.7 as a positive test for NS diagnostic, specificity was 98.6% (95% confidence interval [CI 95%] of 92.4 to 100.0) and sensitivity was 81.3% (CI 95% of 54.4 to 96.0) for NS1 and 98.6% (CI 95% 92.4 to 100.0) and 27.3% (CI 95% 6.0 to 61.0), respectively, for NS2. Positive and negative predictive values were >95% for NS1 and >85% for NS2, for prevalence above and below 20%. Measuring an AI for intrathecal synthesis of specific anti-Treponema pallidum IgG is a new promising tool highly specific for NS diagnosis.

IMPORTANCE In the context of a lack of a gold standard for the diagnosis of neurosyphilis due to either nonspecific or nonsensitive tests, we present in this article a new promising tool highly specific for NS diagnosis. This new test involves measuring an intrathecal synthesis index of specific anti-Treponema IgG by ELISA.

Diagnostic tools for neurosyphilis: a systematic review

Purpose

Increasing incidences of syphilis highlight the preoccupation with the occurrence of neurosyphilis. This study aimed to understand the current diagnostic tools and their performance to detect neurosyphilis, including new technologies and the variety of existing methods.

Methods

We searched databases to select articles that reported neurosyphilis diagnostic methods and assessed their accuracy, presenting sensitivity and specificity values. Information was synthesized in tables. The risk of bias was examined using the Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy recommendations.

Results

Fourteen studies were included. The main finding was a remarkable diversity of tests, which had varied purposes, techniques, and evaluation methodologies. There was no uniform criterion or gold standard to define neurosyphilis. The current basis for its diagnosis is clinical suspicion and cerebrospinal fluid analysis. There are new promising tests such as PCR tests and chemokine measurement assays.

Conclusions

The diagnosis of neurosyphilis is still a challenge, despite the variety of existing and developing tests. We believe that the multiplicity of reference standards adopted as criteria for diagnosis reveals the imprecision of the current definitions of neurosyphilis. An important next step for the scientific community is to create a universally accepted diagnostic definition for this disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06264-8.

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

We conducted a systematic review of relevant syphilis diagnostic literature to address the question, “What is the sensitivity and specificity of the treponemal tests currently approved by the Food and Drug Administration (FDA) for the diagnosis of syphilis (by stage)?” There were 16 treponemal assays evaluated: 13 immunoassays and 3 manual assays (fluorescent treponemal antibody absorbed test [FTA-ABS], microhemagglutination assay for Treponema pallidum antibodies [MHA-TP], Treponema pallidum particle agglutination assay [TP-PA]). MHA-TP and FTA-ABS were less sensitive in primary and secondary syphilis than TP-PA; TP-PA is the most specific manual treponemal assay. There is insufficient evidence to recommend one particular treponemal immunoassay (eg, enzyme immunoassays, chemiluminescence immunoassays, microbead immunoassays) over another based on published performance data. For diagnosis of neurosyphilis, cerebrospinal fluid (CSF) TP-PA has similar performance to CSF FTA-ABS in studies with patients with definitive or presumptive neurosyphilis. However, CSF treponemal testing has limitations in its sensitivity and specificity and should be interpreted within the context of the clinical scenario, additional CSF test results and syphilis prevalence.

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.

Diagnostic role of CXCL13 and CSF serology in patients with neurosyphilis

BACKGROUND

Considering the unknown prevalence of neurosyphilis in West China, and the confusing diagnosis of neurosyphilis, the role of CSF_CXCL13 and syphilis serology was studied to provide a more accurate reference for the clinical detection and diagnosis of neurosyphilis.

METHODS

A retrospective data set I was used to investigate the prevalence of neurosyphilis, as well as the laboratory characteristics of 244 patients. Besides, to explore the diagnostic value of CSF_CXCL13 and syphilis serology for neurosyphilis, another 116 CSF_serum paired samples (data set II) were collected from 44 neurosyphilis and 72 non-neurosyphilis/syphilis patients.

RESULTS

About 6.25% (156 out of 2494) syphilis was neurosyphilis. When Treponema pallidum infection occurs, syphilis serology (sero_TRUST ≥1:16 and sero_TPPA titre ≥1:10240) can be good predictors of neurosyphilis, as well as syphilis CSF serology (CSF_TPPA ≥1:320, CSF_TRUST and venereal disease research laboratory). The sensitivity of serology in neurosyphilis can be complemented by CSF_CXCL13, which could be the therapy monitor of neurosyphilis.

CONCLUSION

Due to the lack of ideal biomarkers for neurosyphilis, the importance of syphilis serology cannot be ignored, and their combination with CSF_CXCL13 or other biomarkers should be further investigated.

German guidelines on the diagnosis and treatment of neurosyphilis

Introduction

In view of the importance of neurosyphilis and the difficulties encountered in diagnosing it, the S1 guideline "Neurosyphilis" has been published by the German Society for Neurology (DGN) in accordance with the stipulations of the Association of the Scientific Medical Societies in Germany (AWMF). The present article is an abridged translation of that German guideline.

Main recommendations

(a) Neurosyphilis can manifest as early neurosyphilis (meningitis, meningovascular neurosyphilis or syphilitic gummas) or late neurosyphilis (tabes dorsalis, general paresis). (b) The following diagnostic criteria help to establish the presence of probable neurosyphilis (always point iv, accompanied by any two of points i to iii): (i) subacute or chronic neuro-psychiatric symptoms; (ii) increased cerebrospinal fluid (CSF) cell count or signs of blood-CSF barrier disruption; (iii) positive effect of anti-neurosyphilis antibiotic therapy on clinical course and CSF findings; (iv) positive TPHA/TPPA or FTA test in serum. (c) The diagnosis of neurosyphilis is confirmed by the subsequent detection of intrathecal production of antibodies against Treponema pallidum. (d) In neurosyphilis, treatment with intravenous penicillin or ceftriaxone for 14 days is recommended. (e) The following parameters can be used to assess a therapeutic effect: clinical findings, serum VDRL, and CSF cell count.

Conclusion

The German guideline on the diagnosis and treatment of neurosyphilis is a practical tool to support clinicians in diagnosing and treating patients with neurosyphilis. This article is an abridged translation of this guideline (Klein MW, J.; Angstwurm, K.; Esser, S.; Hahn, K.; Matschke, M.; Scheithauer, S.; Schoefer, H.; Sturzenegger, M.; Wildemann, B. Neurosyphilis, S1-Leitlinie. Deutsche Gesellschaft für Neurologie, Leitlinien für Diagnostik und Thearpie in der Neurologie 2020).

Multimodal imaging patterns of posterior syphilitic uveitis: a review of the literature, laboratory evaluation and treatment

PURPOSE

To review the multimodal imaging patterns of posterior syphilitic uveitis.

METHODS

A systematic review.

RESULTS

The percentage of syphilis has started to increase again: The World Health Organization has reported 12 million new cases of syphilis each year. In addition, syphilis was responsible for 0.3% of deaths globally in 2002. Eye manifestations happen prevalently in secondary and tertiary stages of syphilis, even though ocular involvement can occur in all stages. Syphilis has the nickname: "the great imitator" since it has no unique clinical presentation, even though posterior uveitis is considered the most common form. Syphilis is known as "the great imitator," making its diagnosis in the presence of posterior uveitis particularly challenging as it presents similarly to other ocular conditions such as acute retinal necrosis. However, with the advent of multimodal imaging some particular patterns of pre-retinal, retinal, retinochoroidal and optic nerve involvement from syphilis can be identified to guide the diagnosis and the laboratory workup.

CONCLUSION

This review highlights the various patterns of pre-retinal precipitates, multifocal retinitis, retinochoroiditis (confluent and placoid) and optic neuritis caused by syphilis, the appropriate laboratory work to be obtained and the treatment to be initiated.

Cerebrospinal Fluid Treponema pallidum Particle Agglutination Assay for Neurosyphilis Diagnosis

Limited data suggest that the cerebrospinal fluid Treponema pallidum particle agglutination assay (CSF-TPPA) is sensitive and a CSF Treponema pallidum hemagglutination assay (CSF-TPHA) titer of ≥1:640 is specific for neurosyphilis diagnosis. CSF-TPPA reactivity and titer were determined for a convenience sample of 191 CSF samples from individuals enrolled in a study of CSF abnormalities in syphilis (training data set). The sensitivity of a reactive test and the specificity for reactivity at serial higher CSF dilutions were determined. Subsequently, CSF-TPPA reactivity at a 1:640 dilution was determined for all available samples from study participants enrolled after the last training sample was collected (validation data set, n = 380). Neurosyphilis was defined as (i) a reactive CSF Venereal Disease Research Laboratory test (CSF-VDRL), (ii) detection of T. pallidum in CSF by reverse transcriptase PCR, or (iii) new vision loss or hearing loss. In the training data set, the diagnostic sensitivities of a reactive CSF fluorescent treponemal antibody absorption test (CSF-FTA-ABS) and a reactive CSF-TPPA did not differ significantly (67 to 98% versus 76 to 95%). The specificity of a CSF-TPPA titer of ≥1:640 was significantly higher than that of lower dilutions and was not significantly different from that of CSF-VDRL. In the validation data set, the diagnostic specificity of a CSF-TPPA titer of ≥1:640 was high and did not differ significantly from that of CSF-VDRL (93 to 94% versus 90 to 91%). Ten CSF samples with a nonreactive CSF-VDRL had a CSF-TPPA titer of ≥1:640. If a CSF-TPPA titer of ≥1:640 was used in addition to a reactive CSF-VDRL, the number of neurosyphilis diagnoses would have increased from 47 to 57 (21.3%). A CSF-TPPA titer cutoff of ≥1:640 may be useful in identifying patients with neurosyphilis when CSF-VDRL is nonreactive.