Incidence and risk factors for the prozone phenomenon in serologic testing for syphilis in a large cohort.

BACKGROUND: The prozone phenomenon is known to be associated with high antibody titers; other associations, such as host factors, have not been elucidated. METHODS: A retrospective analysis was conducted to evaluate the incidence of the prozone phenomenon of the syphilis rapid plasma reagin (RPR) test among 46 856 clinical samples, between June 2010 and June 2013. Logistic regression was used to analyze the risk factors of the prozone phenomenon. RESULTS: Our results showed that the incidence of the prozone phenomenon was low (0.83%) and could occur during any clinical phase, particularly during primary and secondary syphilis. Pregnancy and neurosyphilis were associated with the prozone phenomenon; sex, age, and whether the patient had been treated were not. The results also revealed that the prozone phenomenon not only occurred in patients with a high titer but also could occur in patients with a moderate/low titer. In fact, almost 31% of the patients with the prozone phenomenon had titers ≤1:16. CONCLUSIONS: The prozone phenomenon in the RPR test was associated with the phase of syphilis, pregnancy, and neurosyphilis as well as a range of RPR titers between 1:8 and 1:512. This latter finding is in contrast to previous reports that the prozone phenomenon is associated with very high RPR titers.

Psychiatric manifestations as primary symptom of neurosyphilis among HIV-negative patients.

This study characterizes psychiatric manifestations as a primary symptom of neurosyphilis (NS). Fifty-two of the 169 NS patients presented with psychiatric manifestations, many patients had characteristics of more than one syndrome, including cognitive impairment, personality disorders, delirium, hostility, dysarthria, confusion, disruption of their sleep-wake cycle, fecal and urinary incontinence, dysphoria, paranoia, hallucinations, expansive mood, and mania. Fifty-two patients had positive sera RPR and T. pallidum particle agglutination (TPPA), 75% had positive CSF RPR, 96.2% had positive CSF TPPA, 44.2% had CSF pleocytosis and elevated CSF proteins, and 70.0% had nonspecific, abnormal brain MRIs. These results indicate that NS mimics almost all psychiatric disorders.

Characterization of the classical biological false-positive reaction in the serological test for syphilis in the modern era.

To characterize the CBFP reaction in the modern era, we analyzed the results of parallel rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TPPA) tests from a total of 63,765 blood samples obtained at Zhongshan Hospital in the Medical College of Xiamen University from May 2008 to February 2013. Among the 63,765 tested blood samples, 206 (0.32%) had the CBFP reaction. In multivariate analysis, an increased likelihood of the CBFP reaction was associated with female subjects, subjects ≥80years old, and subjects between 16 and 35years old (P<0.05). The CBFP reaction occurred in association with 17 categories of disease, including 60 types of diseases, in the 206 subjects. To our knowledge, a number of these diseases had not been previously reported to be associated with the CBFP in the RPR test, including false labor, megaloblastic anemias, aplastic anemias, redundant prepuce, congenital malformation of heart, and salpingitis. Among the 206 patients with the CBFP reaction, 35 patients were subjected to follow-up for five years. 26 out of 35 these patients were at a 1:1 initial RPR titer, 8 out of 35 patients were at a 1:2 initial RPR titer, and 1 out of 35 patients were at a 1:4 initial RPR titer. 30 subjects had their RPR seroreverted. In our opinion, additional CBFP research using a large sample population will contribute to the identification of additional underlying serious disorders that are not related to syphilis. Such results could be useful for the prediction and diagnosis of these diseases.

Analysis of 3 algorithms for syphilis serodiagnosis and implications for clinical management.

BACKGROUND: Algorithms for the diagnosis of syphilis continue to be a source of great controversy, and numerous test interpretations have perplexed many clinicians. METHODS: We conducted a cross-sectional study of 24 124 subjects to analyze 3 syphilis testing algorithms: traditional algorithm, reverse algorithm, and the European Centre for Disease Prevention and Control (ECDC) algorithm. Every serum sample was simultaneously evaluated using the rapid plasma reagin, Treponema pallidum particle agglutination, and chemiluminescence immunoassay tests. With the results of clinical diagnoses of syphilis as a gold standard, we evaluated the diagnostic accuracy of the 3 syphilis testing algorithms. The κ coefficient was used to compare the concordance between the reverse algorithm and the ECDC algorithm. RESULTS: Overall, 2749 patients in our cohort were diagnosed with syphilis. The traditional algorithm had the highest negative likelihood ratio (0.24), a missed diagnosis rate of 24.2%, and only 75.81% sensitivity. However, both the reverse and ECDC algorithms had higher diagnostic efficacy than the traditional algorithm. Their sensitivity, specificity, and accuracy were 99.38%-99.85%, 99.98%-100.00%, and 99.93%-99.96%, respectively. Moreover, the overall percentage of agreement and κ value between the reverse and the ECDC algorithms were 99.9% and 0.996, respectively. CONCLUSIONS: Our research supported use of the ECDC algorithm, in which syphilis screening begins with a treponemal immunoassay that is followed by a second, different treponemal assay as a confirmatory test in high-prevalence populations. In addition, our results indicated that nontreponemal assay is unnecessary for syphilis diagnosis but can be recommended for determining serological activity and the effect of syphilis treatment.

Neuropsychiatric disorders secondary to neurosyphilis in elderly people: one theme not to be ignored.

BACKGROUND: Neurosyphilis (NS) may present with neuropsychiatric disorders characterized by cognitive impairment, personality disorders, and confusion, among others. Very few studies have focused on neuropsychiatric disorders secondary to NS in elderly people. METHOD: A retrospective chart review was performed to characterize the psychiatric findings, clinical signs and symptoms, laboratory findings, and brain magnetic resonance imaging results of ten elderly inpatients with NS. RESULTS: In these ten patients, the most common presenting symptoms included a wide variety of psychiatric manifestations. The serum rapid plasma regain (RPR) and Treponema pallidum particle agglutination assay (TPPA) of the ten patients were positive, with positive CSF TPPA and RPR rates of 100% and 60%, respectively. In addition, 90% of the patients demonstrated abnormal imaging, including cerebral atrophy, infarct ischemic stroke, and hydrocephalus. CONCLUSIONS: Our findings support the importance of serological tests for syphilis as a routine component of the evaluation of patients with clinically evident neurological or psychiatric symptoms. If the serology is positive, all of the patients should be examined with a lumbar puncture. Moreover, psychiatric illnesses secondary to NS in the elderly also deserve medical attention.

Spectrum and characterization of movement disorders secondary to neurosyphilis.

There have been frequent reports of Neurosyphilis with atypical features. Syphilitic infection of the central nervous system can result in various movement disorders (MD). The few reports of MD patients with neurosyphilis have been mainly of single patient. Between June 2005 and February 2012 we identified, 169 in-patients with neurosyphilis at Zhongshan Hospital. We performed a retrospective chart review to characterize MD findings, clinical signs and symptoms, misdiagnosis rate, laboratory findings, and brain magnetic resonance imaging results. We found that seven of the 169 neurosyphilis patients presenting with MD, had originally been misdiagnosed with Parkinsonism (4), laryngeal dystonia (1), corticobasal syndrome (1), and sensory ataxia (1). None of these patients were initially suspected of having neurosyphilis. The correct diagnosis was syphilitic meningitis (1), meningovascular neurosyphilis (2), general paresis (3), and tabes dorsalis (1). Among them, six patients had abnormal imaging studies, and sera rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TPPA) from all seven patients were positive. The cerebrospinal fluid (CSF) examinations showed that four patients were CSF-RPR positive (titers ≤1:16) by CSF syphilitic serologic testing, but all seven patients were CSF-TPPA reactive. Moreover, two patients had CSF pleocytosis and four patients had elevated CSF protein expression. Our findings reinforced the importance of routine serologic testing for syphilis should be a part of the evaluation of patients with atypical MD presentations or in whom alternative diagnoses are not forthcoming. When serology is positive, all patients should be examined more thoroughly for neurosyphilis by lumbar puncture.

Assessing cerebrospinal fluid abnormalities in neurosyphilis patients without human immunodeficiency virus infection.

Neurosyphilis (NS) caused by Treponema pallidum (T. pallidum) subspecies pallidum, can affect the central nervous system during any stage of the disease. To assess several laboratory parameters for NS diagnosis, we performed a case control study on 42 hospitalized NS patients negative for human immunodeficiency virus (HIV) and 40 syphilis/non-NS patients, excluding NS patients at Xiamen Zhongshan Hospital from June 2010 to June 2011. Multivariate logistic regression model showed that the cerebrospinal fluid white blood cell (CSF-WBC, P = 0.009) levels, the CSF-LDH (P = 0.006) levels, the albumin quotient (P = 0.009) and the IgA index (P = 0.042) were independently associated with high risk of NS. The receiver operator characteristic (ROC) curve analysis revealed that the optimal cut-offs were 10 × 106 cells/L for the CSF-WBC concentration, 19.3 U/L for the CSF lactate dehydrogenase (LDH) concentration, 7.08 for the albumin quotient, and 0.14 for the IgA index. Combining the CSF-WBC level, the CSF-LDH level, the albumin quotient and the IgA index increased the NS diagnosis sensitivity to 97.6%. T. pallidum particle agglutination (TPPA) index significantly correlated with the CSF-WBC (r = 0.453, P = 0.000), the IgA index (r = 0.446, P = 0.000), the albumin quotient (r = 0.262, P = 0.017), and the CSF-LDH (r = − 0.278, P = 0.012), respectively. In addition, there were correlations between the CSF-WBC and the IgA index (r = 0.329, P = 0.003), and between the CSF-WBC and the albumin quotient (r = 0.306, P = 0.005). Our results indicated that simultaneous testing of CSF-WBC levels, albumin quotient, IgA index and CSF-LDH can help predict the likelihood of NS in HIV-negative patients.

RNA interference inhibits hepatitis B virus gene expression and replication in HepG2-N10 cells.

OBJECTIVE: RNA interference (RNAi) refers to the phenomenon of sequence-specific degradation of homologous mRNA induced by double-stranded RNA. It has been successfully utilized to down-regulate endogenous gene expression or suppress the replication of various pathogens in mammalian cells. In this study, the effect of vector-based small interfering RNA (siRNA) promoted by pSilencer2.0-U6 inhibit hepatitis B virus (HBV) replication in cell culture was evaluated. METHODS: Three fragments of short nucleic acids, respectively, targeting on S, X and C region of HBV genome were inserted into pSilencer vectors after they were annealed with their partly antisense strands. The recombination plasmids were pS, pX and pC. These expression plasmids were transfected into HepG2-N10 cells, a cell line which stably expresses hepatitis B virus surface antigen (HBsAg), hepatitis B virus e antigen (HBeAg) and adw2 subtype Dane particles. The effect of RNAi was evaluated from the changes of DNA, RNA and protein levels. Viral antigens were measured by ELISA. Viral mRNA was analyzed by RT-PCR. The covalent closed circular DNA and genome DNA of HBV secreted into the culture media were measured by quantitative real-time PCR. Analysis of variance was performed for the results. RESULTS: Vector-based RNA interference could potently reduce HBsAg (pS vs pN: 47%, pX vs pN: 30%, and pC vs pN: 25%, P < 0.001) and HBeAg (pX vs pN: 57% and pC vs pN: 66%, P < 0.001) expression in cell culture. Furthermore, RT-PCR analysis showed that viral mRNAs were effectively degraded, thus eliminating the messengers for protein expression as well as templates for reverse transcription (pS and pC vs pN, P < 0.001; pX vs pN, P = 0.003). Quantitative real-time PCR analysis of HBV DNA revealed that vector-based RNA interference can inhibit HBV replication efficiently (pS, pX and pC vs pN, P < 0.001). CONCLUSIONS: Our results indicate that RNAi can inhibit HBV gene expression and replication, and it might have the potential to revolutionize the treatment of HBV.