Comparison of molecular and serological assays on cerebrospinal fluid for the diagnosis of neurosyphilis

The performance of a novel diagnostic criteria for neurosyphilis in HIV-negative patients

Diagnosing neurosyphilis in clinical settings poses significant challenges due to the absence of highly efficient diagnostic criteria. Our objective was to enhance the existing diagnostic criteria and assess their sensitivity and specificity for identifying neurosyphilis in HIV-negative patients. We conducted a retrospective review of patient records from a cross-sectional study carried out between December 2019 and May 2023. This study was designed to explore clinical practices in the diagnosis and treatment of neurosyphilis. We proposed and validated a new set of diagnostic criteria across 782 cases, comparing three different NS criteria for diagnostic efficiency. Among the 782 patients analyzed, 410 were diagnosed with neurosyphilis, while 372 were not. The newly developed NS criteria demonstrated a sensitivity of 99.5% and a specificity of 94.6%, with the added benefit of being user-friendly. In subgroups categorized by neurological symptoms and syphilis stages, the new NS criteria also exhibited high sensitivity and specificity. Statistical analyses confirmed that the novel NS criteria performed comparably well to the expanded NS criteria. The novel NS criteria for HIV-negative patients exhibited high sensitivity and specificity, proving to be both effective and convenient for physicians to implement.

Ocular findings in neurosyphilis: a retrospective study from 2012 to 2022

Purpose

This study aimed to investigate ocular manifestations in patients with neurosyphilis and their association with general indexes.

Methods

This retrospective study was conducted among patients who were hospitalized for neurosyphilis from 2012 to 2022. Clinical manifestations, laboratory tests, brain MRI, and ocular examinations were reviewed and analyzed.

Results

A total of 106 neurosyphilis patients were included, of which 10 patients presented with ocular signs as their initial symptoms. The most common main complaint was reduced vision (6/10), followed by diplopia (2/10) and ptosis (2/10). The causes of vision loss included optic neuropathy (4/6) and posterior uveitis (2/6), with all six patients showing optic nerve involvement. A total of 29 (27.4%) patients exhibited pupil abnormalities. A lumbar puncture was performed on all 106 patients, and abnormal cerebrospinal fluid (CSF) findings were revealed in 101 (95.3%) patients, indicating central nervous involvement. The median white blood cell count in the CSF of the patients with pupil abnormalities was significantly higher than that of those without pupil abnormalities (14.0 vs. 6.0 cells/μl, p = 0.037). In addition, the patients with abnormal pupillary light reflex (PLR) were more likely to have multiple brain lesions compared to those with normal PLR (77.3% vs. 29.2%, p < 0.001).

Conclusion

Optic nerve involvement is the main cause of vision loss in neurosyphilis. Patients with optic neuropathy or posterior uveitis should undergo prompt diagnostic evaluation for syphilis. Pupil abnormalities can serve as indicators of more severe CSF and MRI findings.

Typing of Treponema pallidum in a Brazilian sample and follow-up of treatment using molecular assays

Syphilis remains a significant public health concern, with serological assays being the primary method for diagnosis. However, molecular techniques have proven to be reliable tools for the diagnosis and understanding of the transmission dynamics of Treponema pallidum infection. This study aimed to evaluate the efficacy of syphilis treatment using molecular assays, perform Enhanced Centers for Disease Control and Prevention (ECDC) typing, and analyze resistance (macrolide and doxycycline) in the T. pallidum isolate. PCR assay amplified treponemal DNA only from the lesion sample, whereas qPCR was able to amplify DNA in both lesion and blood samples before treatment. Throughout the treatment follow-up, qPCR effectively did not identify treponemal DNA in the blood for up to one to two weeks after treatment. ECDC typing revealed the genotype 14 e/g in the Brazilian T. pallidum isolate, and the presence of the A2058G mutation in 23 S rRNA gene, indicating macrolide resistance. Although, the G1058C mutation in 16 S rRNA gene was not detected. Notably, qPCR demonstrated its potential for diagnosing T. pallidum in blood samples, even when the treponemal DNA levels were low, enabling more accurate and sensitive diagnosis and guiding better syphilis therapy. In addition, to the best of our knowledge, this study represents the first identification of subtype 14 e/g and azithromycin resistance in a Brazilian T. pallidum isolate.

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.

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.

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.