Architect Syphilis TP Research Articles

The Sero-Prevalance of Syphilis among Blood Donors in District Mardan, A comprehensive comparative analysis and blood group correlation with findings across different cities

The necessity and importance of blood donation well known like in thalassemia, leukemia, lymphoma, patients on chemotherapy and after massive hemorrhage from trauma etc.but it’s transfusion can also lead to some major health problems like transmission of infectious diseases such as syphilis and so on. To prevent transmission of infectious diseases through blood transfusion its screening is performed everywhere. For this purpose, a research study is carried out during January 2019 to April 2019 at Mardan medical complex and Mardan teaching institute (MMC-MTI) Mardan KP, Pakistan. The specimens were collected from 625 blood donors with 619 males and 06 females. The samples were sent to the serology section of the pathology department for the diagnosis of syphilis through architect syphilis TP. The sero-prevalence of syphilis and the variation of prevalence in the previous and recent study were the objective of this research. It has found that only 06 male individuals are found to have syphilis infection while there is no such case reported in female individuals. So the overall sero-prevalence and sero-prevalence in male individuals were the same as 0.96%. The most positive cases were in the age group 38-74 years of age individuals. Which is the most sexually active age and it is reported that 1.8% of the sero-prevalence is found. The seroprevalance of syphilis in A- blood group was 5.5%, B+ patients had 1.56%, and with O+ patients it was 1.16%. From the results and analysis, the sero-prevalence of syphilis in the area and population where the study performed are at more risk of syphilis because per annual 0.30 increases is recorded by comparing the recent results with previous studies. As with the passage of time people are educated so we cannot say that it is because of the lack of awareness no also. So the opinion is that the lifestyle, social interaction of people with one another and carelessness in sexual intercourses is the main risk factors responsible for this increase in sero-prevalence of syphilis.

Screening for maternal and congenital syphilis with a chemiluminescence immunoassay in a South African private specialist healthcare sector setting


 
 
 
 Background. Syphilis is a sexually transmitted infection that is most frequently found in lower socio-economic groups globally and is associated with significant maternal and fetal complications. In South Africa (SA), the last two to three decades have seen a rise in the number of people in the low and middle economic social groups seeking private specialist healthcare services.Objective. To evaluate the prevalence rates of maternal and congenital syphilis in a private specialist healthcare setting.
 Methods. The laboratory case records of women who had antenatal maternal syphilis (MS) screening using the automated chemiluminescence immunoassay (Architect Syphilis TP) in a private laboratory facility in Durban were reviewed.Results. A total of 9 740 individual maternal serum samples were analysed and 256 were Architect Syphilis TP positive, resulting in a MS prevalence rate of 2.7%. Of the less than three-quarters of exposed neonates tested (71.1%; n=182/256), 38.5% (n=70/182) were Architect syphilis TP positive. Less than a tenth of exposed neonates (2.43%; n=6) had only rapid plasma reagin (RPR) titers test whereas 26.6% (n=68/256) did not have a syphilis screen test. Based on the 182 exposed neonates tested, the congenital syphilis (CS) prevalence from the laboratory records was 7.7%. The highest rate of MS was in the ≥35 years age group.
 Conclusion. The prevalence of MS in the private specialist healthcare sector in SA is relatively high and warrants continued maternal antenatal screening during early pregnancy across all socio-economic groups. The high rate of MS in the age group over 35 years warrants further investigations and explanation.
 
 
 

Correlation of Treponemal Chemiluminescent Microparticle Immunoassay Screening Test Signal Strength Values With Reactivity of Confirmatory Testing.

Automated chemiluminescent microparticle immunoassays (CMIAs) are the most common first step at high-volume laboratories for syphilis screening. If the initial screening test is reactive, 1 more treponemal test is required, resulting in increased cost. In this multicenter study, we aimed to determine the correlation between the CMIA signal-to-cutoff ratio (S/Co) and the confirmatory tests to reduce unnecessary confirmatory testing. Eight hospitals from 5 provinces participated in this study. All laboratories used Architect Syphilis TP CMIA (Abbott Diagnostics, Abbott Park, IL) for initial screening. Treponema pallidum hemagglutination (TPHA), rapid plasma reagin (RPR), and fluorescent treponemal antibody absorption (FTA-ABS) were used as confirmatory tests according to the reverse or European Centre for Disease Prevention and Control algorithms. A receiver operating characteristic analysis was used to determine the optimal S/Co ratio to predict the confirmation results. We evaluated 129,346 serum samples screened by CMIA between January 2018 and December 2020. A total of 2468 samples were reactive; 2247 (91%) of them were confirmed to be positive and 221 (9%) were negative. Of the 2468 reactive specimens, 1747 (70.8%) had an S/Co ratio ≥10.4. When the S/Co ratios were ≥7.2 and ≥10.4, the specificity values were determined to be 95% and 100%, respectively. In a subgroup of 75 CMIA-positive patients, FTA-ABS was performed and 62 were positive. Among these FTA-ABS-positive patients, 24 had an S/Co ratio <10.4, and negative TPHA and RPR. We propose a potentially cost-effective reverse screening algorithm with a treponemal CMIA S/Co ratio ≥10.4, obviating the need for secondary treponemal testing in about 71% of the screening-reactive samples. This would substantially reduce the confirmatory testing volume and laboratory expenses. However, in high-risk group patients with CMIA positive results, S/Co ratio <10.4, and negative TPHA and RPR, FTA-ABS may be used for confirmation.

Clinical performance evaluation of Elecsys HIV Duo, Anti-HCV II, HBsAg II, Anti-HBc II, and Syphilis assays for routine screening of first-time blood donor samples at a French blood donation center.

Implementing fully automated analyzers has become a crucial safety step in blood donation centers. The Elecsys® assays were evaluated on the cobas e 801 module (Roche Diagnostics) for routine first-time blood donor screening. Five Elecsys infectious disease assays were tested on the cobas e 801 module at Etablissement Français du Sang, Montpellier, France (March-April 2018). The performance of Elecsys HIV Duo, Anti-HCV II, HBsAg II, Anti-HBc II, and Syphilis assays was compared with PRISM HIV O Plus, HCV, HBsAg, HBcore, and newbio pk TPHA assays (specificity analyses)/ARCHITECT Syphilis TP (sensitivity analyses), respectively. Specificity was determined in residual fresh serum samples from unselected first-time blood donors (n≥5195 per parameter). Elecsys assay sensitivity was tested using 30 preselected, positively characterized samples per assay and compared with archived routine testing data for comparator assays. Across all parameters, specificities for repeatedly reactive samples ranged from 99.81-100.00% for Elecsys assays and 99.71-99.98% for comparator assays. Sensitivities of Elecsys and comparator assays were the same for hepatitis C (85.19%), hepatitis B surface antigen (70.00%), hepatitis B core antigen antibodies (100.00%), and syphilis (100.00%). The sensitivity of the Elecsys HIV Duo assay was higher than the comparator assay (83.33% vs. 76.67%), but the difference was not statistically significant. Elecsys infectious disease assays on the cobas e 801 module demonstrated high specificity and sensitivity for screening first-time blood donor samples, and were comparable with other commercially available assays. The Elecsys assays are reliable tests for screening blood donations.

Evaluation of BioPlex 2200 Syphilis Total With Automated Rapid Plasma Reagin: Experience From a Tertiary Medical Center.

Treponema-specific assays are widely adopted in the first step of the reverse algorithm of serologic syphilis screening. The new BioPlex 2200 Syphilis Total and rapid plasma reagin (RPR) test is designed to perform the first 2 steps of the algorithm simultaneously. However, limited data regarding the BioPlex Syphilis Total and RPR in clinical practice exist. A total of 293 random samples at a tertiary medical center were tested by BioPlex Syphilis Total and RPR, BioPlex Syphilis IgG, Architect Syphilis TP, and BD Macro-Vue RPR card. Treponema pallidum particle agglutination (TP-PA) assay and clinical chart review were used to resolve discrepancies. Comparisons were performed among treponemal-specific assays and between 2 RPR tests. Good overall agreements (>91%) were achieved between BioPlex Syphilis Total, BioPlex Syphilis IgG, and Architect Syphilis TP. Overall agreement between BioPlex RPR and BD RPR was 86.8% with positive percent agreement of 66.7% and negative percent agreement of 96.3%. There were 37 discordant samples including 30 with BD RPR+/BioPlex RPR- and 7 with BD RPR-/BioPlex RPR+. Negative BioPlex RPR results were observed in samples with reactive BD RPR: 10 (91%) of 11 for BD RPR 1:1, 13 (65%) of 20 for BD RPR 1:2, 6 (35%) of 17 for BD RPR 1:4, and 1 (7%) of 14 for BD RPR 1:8. The discordant samples were predominantly from patients with high-risk of syphilis reinfection and included 9 patients with an early reinfection. Our results demonstrated that BioPlex Syphilis Total and Architect Syphilis TP performed similarly. The BioPlex RPR missed a small number of early syphilis reinfections, and its implementation should depend on the patient population that the laboratory serves.

Is the Second Treponemal Test Necessary in the Reverse Algorithm for the Diagnosis of Syphilis?

This study was performed to investigate the necessity of the second treponemal test and to evaluate the diagnostic performance of the first treponemal test in the reverse algorithm of syphilis diagnosis. Abbott Architect Syphilis TP assay, a chemiluminescence immunoassay (CIA), was used as the first step treponemal test. Treponema pallidum haemagglutination assay (TPHA) test results of reactive samples from the first test were recorded. TPHA test result was considered as confirmatory. TPHA test results were grouped according to their Abbott Architect Syphilis TP assay results and they were compared with Mann-Whitney U test. For Abbott Architect Syphilis TP assay, a cutoff value with 100% specificity was determined via a ROC curve analysis which would render TPHA test unnecessary. Out of 146,800 samples 2,646 were reactive in the first step. Of those, 2,002 had a TPHA test result. Of the 2,002 TPHA tests, 1,706 were positive and 296 were negative. TPHA positive and negative groups have significantly different CIA signal/cutoff values. Using a ROC curve built for evaluation of the first-step test, the maximum Youden's index value was found as 5.26. If this value would be accepted as cutoff, it would have a specificity of 85%. The specificity of 100% can be reached if a new cutoff value is set to 27.83. Calculated cutoff value with 100% specificity is not practically applicable. It achieves saving of TPHA test in only six percent of reactive samples. Architect Syphilis TP assay is advantageous in large laboratories but is not enough to lead diagnosis without a second treponemal assay. Therefore it was decided to continue the reverse algorithm with dual treponemal assays.

Implementation of the reverse screening syphilis algorithm in a clinical laboratory

Syphilis remains a public health concern worldwide, the accuracy of diagnostic tests is critical for its successful control. Currently, there are two approaches to the diagnosis of syphilis using serological tests: the traditional algorithm and the reverse algorithm. The goal of this study was to analyse the advantages and disadvantages in the implementation of the syphilis reverse-screening algorithm in an outpatient clinical laboratory. An observational cross-sectional study was carried out analyzing 246 reactive sera from a total of 14700 requests for syphilis serology. Chemiluminescent assay ARCHITECT Syphilis TP, V.D.R.L. and FTA-Abs were performed. Among 246 reactive sera by ARCHITECT Syphilis TP, 129 were reactive and 117 were non-reactive by V.D.R.L. the last mentioned resulted in 97 reactive and 20 non-reactive by FTA-Abs, suggesting false positives (0.13%). Two patients with primary infection were detected, that were not detected by V.D.R.L. and one pregnant woman with primary infection with a high value S/CO and V.D.R.L.:1 dils. Among the advantages of using a reverse algorithm were greater sensitivity in the detection of patients with primary syphilis; automation, complete traceability of the samples; objective interpretation and conclusive results.

700: Diagnostic accuracy of Abbott ARCHITECT Syphilis TP chemiluminescent immunoassay in pregnant women

An alternative to a traditional syphilis diagnostic algorithm, the reverse sequence algorithm (treponemal antibody with reflex to rapid plasma reagin (RPR)) utilizes a screening test such as Abbott ARCHITECT Syphilis TP chemiluminescent immunoassay (CIA) to provide objective, rather than subjective, results. We evaluated the diagnostic accuracy of the CIA screen in pregnant women compared to the traditional RPR prior to clinical implementation of the reverse algorithm at our hospital. Prospectively collected blood samples from routine prenatal RPR tests were collected and frozen. Samples were batch-tested with treponemal-specific CIA (index test). Women with reactive (positive) RPR had particle agglutination assay (TPPA, gold standard) available for analysis; for RPR-/CIA+ samples, TPPA was performed. We calculated sensitivity, specificity, predictive value, and false positive rate of the CIA test in pregnant women and evaluated perinatal outcomes of women with reactive CIA. Of 1,605 specimens, 35(2.1%) were RPR+, including 24(69%) CIA+/TPPA+ and 11(31%) CIA-/TPPA- (false positive RPR) (Figure 1). Of 1,570 RPR- specimens, 14(0.9%) were CIA+, including 13(93%) confirmed TPPA+, and 1(7%) TPPA- (false positive CIA). Diagnostic performance of the CIA (with 95% CI) was: sensitivity 100%(90.5-100%), specificity 99.9%(99.6 -100%), positive predictive value 97.4% (86.2-99.9%), and false positive rate 0.06%(0.002-0.4%)(Table 1). Among 37 CIA+/TPPA+ women, 11(30%) had previously treated syphilis, 19(51%) had active infection, and 7(19%) had RPR- status which did not require treatment or investigation by the local health department. There was no difference in age, parity, or race/ethnicity among women with RPR+/CIA+/TPPA+ versus RPR-/CIA+/TPPA+ results. One stillbirth occurred in a woman with early, active RPR+/CIA+/TPPA+ syphilis identified at delivery; no adverse perinatal outcomes occurred among women with RPR-/CIA+/TPPA+ results. Compared with the traditional RPR screening test, the treponemal-specific CIA accurately diagnoses current or past syphilis in pregnancy. While women with RPR+/CIA+/TPPA+ and RPR-/CIA+/TPPA+ results had similar demographic characteristics, the clinical significance of RPR-nonreactive status in pregnancy is unclear: adverse perinatal outcomes were limited to women with untreated, RPR+/CIA+/TPPA+ results in our study.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Investigation of syphilis coinfection and performance of the Architect Syphilis Tp ELISA screening test in HIV positive patients

Limited data on syphilis coinfection in human immunodeficiency virus (HIV) positive cases exist in Turkey. Our aim is to investigate syphilis coinfection and to evaluate the compatibility of the screening Architect Syphilis Tp ELISA with the fluorescent treponemal antibody absorption (FTA-abs) confirmation test in HIV positive cases. Totally 519 HIV positive patients were included in the study. Enzyme linked fluorescent assay (ELFA) was used as a screening test and positive samples were confirmed by line immunassay (LIA). In order to discriminate acute HIV infection and false ELISA positivity, HIV-1 RNA PCR was performed in ELFA positive and LIA negative samples. Architect Syphilis TP ELISA was used for the detection of total antibodies against Treponema pallidum in HIV positive patients. Positive results were confirmed by the FTA-abs test. Out of 519 HIV-1 positive patients, IgG and IgM positivity, and only IgG positivity was detected as 1.9% and 11.4% in all the samples, respectively. A total of 79 (15.2%) sera were positive with Architect Syphilis Tp ELISA test and 69 (13.3%) were positive with FTA-abs test. Statistically significant, almost perfect agreement was found between Architect Syphilis Tp ELISA and FTA-abs tests (kappa = 0.921 and P < 0.001). Implementation of syphilis and HIV screening tests together among risk groups is considered to be appropriate.

Performance evaluation of nine different syphilis serological tests in comparison with the FTA-abs test

BackgroundSerological methods have great importance for the detection of Treponema pallidum antibodies in syphilis diagnosis. The goal of the present study is to evaluate various commercially available screening assays in comparison with the FTA-abs test. MethodsA total of 363 serum samples were enrolled in the study. Following routine testing including RPR and TPHA tests, each sample was tested by treponemal immunoassays (Chorus Syphilis Screen Recombinant, Architect Syphilis TP, Syphilis Virclia Monotest, Siemens Advia Centaur Syphilis, Euroimmun Treponema pallidum Screen ELISA, Vircell Syphilis ELISA IgG + IgM, SD Bioline Syphilis). The result obtained from each test was compared with the confirmatory FTA-abs test. Kappa (κ) coefficients were used to compare the concordance of the tests. ResultsWhen the various tests were evaluated in comparison with the FTA-abs test, the sensitivity, specificity and percent agreement of each test were as follows: Architect Syphilis TP, 92.3%, 94.5%, 92.8%; Chorus Syphilis Screen Recombinant, 87.9%, 91.2%, 88.7%; Syphilis Virclia Monotest, 80.5%, 97.8%, 84.9%; Siemens Advia Centaur Syphilis, 87.5%, 89%, 87.9%; Euroimmun Treponema pallidum Screen ELISA, 87.5%, 85.7%, 87.1%; Vircell Syphilis ELISA IgG + IgM, 73.2%, 62.6%, 70.5%; TPHA, 89%, 63.7%, 82.6%; SD Bioline Syphilis, 58.1%, 94.5%, 67.2%; RPR test, 57.7%, 57.1%, 57.6%. ConclusionThe results of the present study show that Treponema pallidum specific immunoassays with a performance similar or better than TPHA test generally performed well with the confirmatory FTA-abs test and may be an alternative for screening total antibodies in syphilis infection.

Determination of a Sample-to-Cutoff Ratio to Predict True-Positivity in Blood Donor Samples Screened for Syphilis by a Chemiluminescent Immunoassay

Purpose: The use of Architect Syphilis TP CMIA in the blood bank raised the number of syphilis positive samples requiring confirmation. The aim of this study is to determine a sample-to-cutoff s/co ratio for CMIA predicting ≥95% of true-positive samples to reduce these samples.Methods: CMIA reactive samples n=177 were evaluated by Western blot WB as the reference standard, as well as by Treponema pallidum hemagglutination TPHA and Rapid Plasma Reagin RPR tests. The s/co ratio predicting ≥95% of true-positive samples was defined as the threshold leaving ≥95% of WB confirmed samples greater than the particular value. The performances of TPHA and RPR tests were also evaluated with respect to s/co ratios of CMIA positive samples.Results: The s/co ratio 15.17 predicted a true-positive result for ≥95% of samples tested 95% confidence interval: 85.9–99.3 and reduced the number of samples requiring confirmation by 29.9%. Higher s/co ratios were correlated with the increasing number of bands on WB strips p95% of positive samples with s/co ratios ≥15, its sensitivity was 47.7%.Conclusion: Higher s/co ratios can be used to define true-positivity and may indicate an active infection. TPHA may replace WB to confirm samples with s/co ratios between 3 and 15. RPR should not be used as a screening test in blood banks as it could miss almost half of the truepositive samples

Screening and identification of immunoactive FlaB protein fragments of Treponema pallidum for the serodiagnosis of syphilis.

Flagellin is a classical pathogen-associated molecular pattern that can evoke a robust immune response. We have demonstrated previously that three full-length flagellins of Treponema pallidum, namely FlaB1, FlaB2 and FlaB3, did have diagnostic value in the serodiagnosis of syphilis. Here, we selected and constructed three recombinant fragments of each complete FlaB, both the conserved N-terminal and the C-terminal region, and the middle variable part, with the goal of exploring fragments unique to Treponema pallidum for use as antigen targets in a fragment-based serological test. The diagnostic performance of fragments was evaluated using different panels of serum specimens (=332) by indirect IgG enzyme-linked immunosorbent assay. The data showed that all the conserved fragments exhibited excellent sensitivities (91.1-95.0%) but poor specificities (64.1-78.4%), while the three middle regions demonstrated higher sensitivities and specificities for detecting IgG antibody, with 92.7% and 96.1% for FlaB1M ('B1M'), 91.6% and 94.8% for B2M, and 95.0% and 100% for B3M, respectively. In comparison, the sensitivity and specificity of Architect Syphilis TP was found to be 95.5% and 94.8%, respectively. These findings revealed that the middle portion of each FlaB had epitopes specific for Treponema pallidum and identified B3M as a promising candidate antigen for the serodiagnosis of syphilis.

Analytical and clinical comparison of Elecsys syphilis (Roche®) – Architect syphilis TP and reformulated Architect syphilis TP (Abbott®) assay

The performance of Elecsys Syphilis was compared to Architect Syphilis TP and Reformulated Architect Syphilis TP. The overall sensitivity and specificity were 98.4% and 99.5%, 97.7% and 97.1%, and 99.2% and 99.7% respectively. The assays are comparable and considered adequate for syphilis screening.

Evaluation of Elecsys Syphilis Assay for Routine and Blood Screening and Detection of Early Infection

Treponema pallidum infections can have severe complications if not diagnosed and treated at an early stage. Screening and diagnosis of syphilis require assays with high specificity and sensitivity. The Elecsys Syphilis assay is an automated treponemal immunoassay for the detection of antibodies against T. pallidum. The performance of this assay was investigated previously in a multicenter study. The current study expands on that evaluation in a variety of diagnostic settings and patient populations, at seven independent laboratories. The samples included routine diagnostic samples, blood donation samples, samples from patients with confirmed HIV infections, samples from living organ or bone marrow donors, and banked samples, including samples previously confirmed as syphilis positive. This study also investigated the seroconversion sensitivity of the assay. With a total of 1,965 syphilis-negative routine diagnostic samples and 5,792 syphilis-negative samples collected from blood donations, the Elecsys Syphilis assay had specificity values of 99.85% and 99.86%, respectively. With 333 samples previously identified as syphilis positive, the sensitivity was 100% regardless of disease stage. The assay also showed 100% sensitivity and specificity with samples from 69 patients coinfected with HIV. The Elecsys Syphilis assay detected infection in the same bleed or earlier, compared with comparator assays, in a set of sequential samples from a patient with primary syphilis. In archived serial blood samples collected from 14 patients with direct diagnoses of primary syphilis, the Elecsys Syphilis assay detected T. pallidum antibodies for 3 patients for whom antibodies were not detected with the Architect Syphilis TP assay, indicating a trend for earlier detection of infection, which may have the potential to shorten the time between infection and reactive screening test results.

A novel ELISA using a recombinant outer membrane protein, rTp0663, as the antigen for serological diagnosis of syphilis.

The lack of Treponema pallidum-specific antigens with highly accurate diagnosis makes the diagnosis of syphilis challenging. A soluble recombinant version of a new diagnostic protein Tp0663 has been produced. The serodiagnostic potential of this protein was assessed by screening 3326 serum samples simultaneously evaluated by rapid plasma reagin and T. pallidum particle agglutination tests. Kappa (κ) coefficients were used to compare the concordance between clinical diagnosis and the Tp0663-based ELISA or the ARCHITECT Syphilis TP chemiluminescent immunoassay (Abbott GmbH and Co. KG). Using the results of clinical diagnosis as the gold standard, the sensitivity and specificity of Tp0663 were found to be 98.83% (95% confidence interval (CI) 96.61-99.60%) and 100% (95% CI 99.88-100%), respectively. In comparison, the ARCHITECT Syphilis TP assay was found to have a lower sensitivity (97.27%, 95% CI 94.46-98.67%) and specificity (99.61%, 95% CI 99.32-99.78%). In particular, the ARCHITECT Syphilis TP exhibited a false-positive rate of 0.39%. Moreover, the ELISA was in perfect agreement with the gold standard, with a κ value of 0.99, comparable to that of ARCHITECT Syphilis TP (0.96). These results identified Tp0663 as a novel serodiagnostic candidate with great potential for developing novel tests for the diagnosis of syphilis.

Evaluation of FlaB1, FlaB2, FlaB3, and Tp0463 of Treponema pallidum for serodiagnosis of syphilis

Syphilis is a multistage disease caused by the invasive spirochete Treponema pallidum subsp. pallidum, and accurate diagnosis is important for the prevention and treatment of syphilis. Here, to identify appropriate diagnostic antigens for serodiagnosis of syphilis, 6 recombinant proteins were expressed in Escherichia coli and purified, including flagellins (FlaB1 [Tp0868], FlaB2 [Tp0792], and FlaB3 [Tp0870]), Tp0463, Tp0751, and Tp1038. The sensitivities were determined by screening sera from individuals with primary (n=82), secondary (n=115), latent (n=105), and congenital (n=65) syphilis. The specificities were determined by screening sera from uninfected controls (n=30) and potentially cross-reactive infections including Lyme disease (n=30), leptospirosis (n=5), and hepatitis B (n=30). Our data showed that FlaB1, FlaB2, FlaB3, Tp0463, and Tp1038 exhibited higher overall sensitivities and specificities for detecting IgG antibody, with 95.4% and 98.9%, 92.6% and 95.8%, 95.1% and 95.8%, 92.6% and 97.9%, and 95.9% and 98.9%, respectively. In contrast, Tp0751 demonstrated only an overall sensitivity of 39.2%. For comparison, the sensitivity and specificity of Architect Syphilis TP were determined to be 98.1% and 93.7%, respectively. In addition, FlaB1, FlaB2, FlaB3, and Tp0463 demonstrated excellent performance for detecting IgM antibody in primary and congenital syphilis, with sensitivities of 76.8% and 83.1%, 72.0% and 87.7%, 74.4% and 89.2%, and 64.6% and 75.3%, respectively. These results indicate that FlaB1, FlaB2, FlaB3, and Tp0463 could be as novel diagnostic candidates for serodiagnosis of syphilis.

P07.20 Field evaluation of a dual rapid diagnostic test for hiv infection and syphilis in port-au-prince, haiti

Introduction Congenital syphilis is responsible for over 500,000 adverse pregnancy outcomes globally every year, including stillbirth, fetal loss, neonatal death, low birth weight, preterm birth and syphilis infection in the infant. In Haiti, 90% of pregnant women report at least one antenatal visit. We evaluated the field performance of the SD BIOLINE HIV/Syphilis Duo test in a high-risk setting in Port-au-Prince, Haiti using whole blood fingerprick specimens. Methods GHESKIO (Haitian Study Group for Kaposi’s sarcoma and Opportunistic Infections) clinic attendees 18 years of age or older were invited to participate. Venipuncture blood specimens were used for reference testing: for HIV, Murex HIV-1.2.0 (DiaSorin S.p. A.) or Determine HIV-1/2 (Alere Inc). Positive results were confirmed with the HIV(1+2) Rapid Test Strip (KHB Shanghai Kehua Bioengineering Co. Ltd). For Treponema pallidum (Tp) antibody comparison, Treponema Pallidum Hemagglutination Assay (TPHA) (Human Gesellschaft fur Biochemica und Diagnostica mbH) was used. For 21 TPHA indeterminate results, specimens were retested using a Tp enzyme-linked immunosorbent assay test (ELISA) (Architect Syphilis Tp, Abbott Laboratories). Sensitivity and specificity were calculated and the exact binomial method was used to determine 95% confidence intervals (CI). Results Of 298 study participants, 61 (20.5%) were male. Of 237 females, 49 (20.7%) were pregnant. For the HIV component, sensitivity and specificity were 99.2% (95% CI: 95.8%, 100%) and 97.0% (95% CI: 93.2%, 99.0%), respectively. All 21 TPHA indeterminate results were Tp ELISA reactive. For the Tp component, sensitivity and specificity were 96.5% (95% CI: 91.2%, 99.0%) and 90.8% (95% CI: 85.7%, 94.6%), respectively. In pregnant women, the HIV component sensitivity and specificity were 93.3% (95% CI: 68.0%, 99.8%) and 94.1% (95% CI: 80.3%, 99.3%), respectively; and for the Tp component were 100% (95% CI: 81.5%, 100%) and 96.8% (83.3%, 99.9%), respectively. Conclusion The HIV antibody component of the Duo test shows excellent performance. The Treponema pallidum antibody component showed high sensitivity, and slightly lower specificity. Amongst pregnant women the test performed very well. Disclosure of interest statement The study was supported in part by Standard Diagnostics.

Evaluation of the BioPlex 2200 Syphilis System as a First-Line Method of Reverse-Sequence Screening for Syphilis Diagnosis

Despite recent technological advances, the diagnosis of syphilis remains a challenging enterprise. Actually, most high-volume laboratories have adopted the "reverse algorithm" due several factors, including the potential to automate testing. Recently, immunoassays processed on random-access systems have been proposed as screening tests. The purpose of this study was to evaluate diagnostic performances of BioPlex 2200 Syphilis IgG and BioPlex 2200 Syphilis IgM, tests based on Multiplex Flow technology, in comparison with the performance of Architect Syphilis TP, a chemiluminescent immunoassay for the detection of IgG and/or IgM anti-Treponema pallidum antibodies. A retrospective study was performed with a panel of 100 blood donor sera, a panel of 350 clinical and laboratory-characterized syphilitic sera, and 170 samples obtained from subjects with potentially interfering conditions. Moreover, 200 unselected samples submitted to the Microbiology Laboratory of St. Orsola Hospital in Bologna for routine screening for syphilis were evaluated. As confirmatory tests, T. pallidum hemagglutination and Western blot assays were used. Considering the IgG Western blot (WB) assay to be the gold standard method, BioPlex 2200 Syphilis IgG specificity was far higher than Architect Syphilis TP specificity (89.7% versus 78.4%, respectively), whereas the sensitivity was 100% for both automated methods. Compared to the IgM WB assay, BioPlex 2200 Syphilis IgM performed with a specificity of 94.9%, whereas the sensitivity was 84.8%. Considering the excellent ease of use and automation, the high sample throughput and its valuable analytical performances, BioPlex Syphilis 2200 IgG could represent a suitable choice for high-volume laboratories. BioPlex Syphilis 2200 IgM could be considered a good addition to IgG testing for uncovering active infections.

The Clinical Significance Comparison of a Latex Agglutination Based Syphilis Screening Test at Low Antibody Titer

The rapid increase of syphilis underscores a tremendous need to carefully evaluate many new serological tests for syphilis and choose efficient and economical strategies for syphilis screening, especially in the case of primary infection with low antibody titer. Between 2011 and 2012, 73 patients' sera samples were included in this retrospective study. They were either TRUST or TPPA reactive, either LA (latex agglutination) based auto3 TP or CLIA (chemiluminescence assay) based Architect Syphilis TP assay reactive. The contradictory weak response samples were further examined by FTA-Abs method. TPPA could not give reactive results in samples with antibody concentration less than 10 mIU. Auto3 TP reagent shows good linearity at low antibody titers and was more sensitive than TPPA, while the former does not show significant superiority compared to the Architect Syphilis TP assay at low antibody titer, except that it is suitable for adaptation on diverse automated chemistry analyzers.

Characterization of sera with discordant results from reverse sequence screening for syphilis.

Reverse sequence screening for syphilis (RSSS) (screening with treponemal tests, followed by confirmation with nontreponemal tests) has been increasingly adopted. CDC recommends confirmation of discordant results (reactive EIA/CIA and nonreactive nontreponemal test) with Treponema pallidum particle agglutination assay (TP-PA). We characterized sera with discordant results from RSSS with Architect Syphilis TP CIA. Among 15,713 screening tests using Architect Syphilis TP at Seoul National University Gangnam Center between October 2010 and May 2011, 260 (1.7%) showed reactive results. Rapid plasma reagin (RPR) and TP-PA were performed on 153 available sera among them. On sera with discordant results between Architect Syphilis TP and TP-PA, INNO-LIA Syphilis Score and FTA-ABS were performed. Among 153 sera, RPR was nonreactive in 126 (82.4%). Among them, TP-PA was positive in 103 (81.7%), indeterminate (±) in 7 (5.6%), and negative in 16 (12.7%). Out of 16 CIA(+)/RPR(−)/TP-PA(−) sera, INNO-LIA Syphilis Score and/or FTA-ABS were negative on 14 sera. Out of 7 CIA(+)/RPR(−)/TP-PA(±) sera, INNO-LIA Syphilis Score and FTA-ABS were positive/reactive in 6 sera. RSSS with confirmation by TP-PA on sera with discordant results between Architect Syphilis TP and RPR effectively delineated those discordant results and could be successfully adopted for routine checkup for syphilis.