Nontreponemal Tests Research Articles

Epidemiologic Characterization and Risk Factors for Congenital Syphilis in Northeast Mexico: A Case-control Study 2016–2024

Background: Congenital syphilis (CS) is an infectious disease caused by Treponema pallidum, which is transmitted through the placenta during pregnancy. Since 2001, a notable and consistent rise in the prevalence of CS cases has been observed, especially in low- and middle-income countries. Currently, information regarding the risk factors for this phenomenon has been scarcely addressed. Methods: A case-control study was conducted to analyze the risk factors for CS. Cases of CS were defined according to scenarios 1 and 2 from Centers for Disease Control criteria, while controls were considered those from scenarios 3 and 4. Data were collected from clinical records from 2016 to 2024 from a hospital in the metropolitan area of Monterrey, Mexico. Statistical analysis was conducted through SPSS V.22. Results: In total 297 syphilis-infected mothers were included in the analyses. Multivariable logistic regression analysis showed that CS was related to late maternal diagnosis, especially after birth [OR: 4.352 (1.313–14.423)]. Additionally, women with a high nontreponemal serum test titer (≥1:8) had an increased risk of delivering an infant with CS [OR: 4.380 (1.946-9.856)]. Infants born to mothers receiving adequate treatment [OR: 0.213 (0.101-0.450)] were a protective factor. Conclusion: CS is a major public health worldwide. Adequate treatment is critical for the prevention of CS. Strategies focusing on prenatal care, early diagnosis, and adequate treatment among those with high nontreponemal titer should be strengthened to prevent CS.

Improved efficiency using sequential automated immunoassays for syphilis screening in blood donors.

The serodiagnosis for syphilis usually follows two methodologies-a "traditional" algorithm using a non-treponemal test followed by confirmation using a treponemal test, or a "reverse" algorithm using a treponemal test followed by a non-treponemal test. There are limited reports in the literature of using a modified reverse algorithm (treponemal test followed by a second treponemal test), and to the best of knowledge, there are currently no published articles using two highly sensitive automated immunoassays to aid the serodiagnosis of syphilis. In addition, the Treponema pallidum particle agglutination (TPPA) assay is commonly used as a confirmatory test for the diagnosis of syphilis. With the withdrawal of the TPPA assay from Australia and presumably from the global market also, alternative testing algorithms are now required. This study provides proof of concept for using sequential immunoassays in the diagnosis of syphilis.

Lack of Serological Response by Delivery to Syphilis Treatment Does Not Impact Pregnancy Outcomes.

Objectives: Maternal syphilis can lead to serious adverse pregnancy outcomes, including neonatal death. A 4-fold decline in blood non-treponemal titer at six months after the treatment of syphilis compared to the baseline is considered as an adequate serological response. However, the duration of normal human gestation does not allow the ascertainment of an adequate serological response. Aim: The aim of this study was to assess correlations between the lack of a 4-fold decrease in non-treponemal titer by delivery after syphilis treatment and fetal and newborns' condition and serological outcomes. Methods: Fourteen pregnant patients (gestational age 16-22 weeks) diagnosed with early syphilis (secondary or latent) were treated with intramuscular benzathine penicillin and subsequently monitored clinically, serologically, and ultrasonographically at monthly intervals. Based on the non-treponemal test results at delivery, patients were stratified into two groups: those with a 4-fold decline in titers and those without such a decline. All newborns were clinically and serologically assessed for congenital syphilis at birth and then monitored until serological tests became negative. Results: Fifty percent of the included women did not achieve a 4-fold decline in non-treponemal titer by delivery. Patients from the group showing a 4-fold decline in RPR titer at delivery and those without such a decline did not differ in basic demographic and clinical characteristics or in ultrasound parameters used for fetal assessment. Based on the clinical and laboratory assessments of newborns on the day of delivery and during a 6-month follow-up, none were diagnosed with congenital syphilis or required treatment for syphilis. Conclusions: The lack of an adequate serological response to syphilis therapy by delivery among patients treated between 16 and 22 weeks of pregnancy does not appear to be associated with adverse fetal and neonatal outcomes.

Exposure to Treponema pallidum among Female Sex Workers: A Retrospective Study Conducted in the State of Pará, Brazilian Amazon.

Syphilis remains a significant global public health issue, and female sex workers (FSWs) are highly vulnerable to the etiological agent of this disease. This study aimed to describe the prevalence of exposure to Treponema pallidum, as well as the vulnerability factors among FSWs in the state of Pará, Brazilian Amazon. A cross-sectional, retrospective study involving 360 FSWs from five cities in Pará was conducted from 2005 to 2007. Blood samples were collected for treponemal and non-treponemal testing, and epidemiological information was obtained through interviews. The exposure rate to T. pallidum was 37.7% (136/360), and the majority of FSWs had serological results indicating past exposure (21.1%). Among the FSWs exposed to T. pallidum, most of them were single, aged 23 to 42 years old, had less than 8 years of schooling, and had a family income of between 1 and 3 minimum wages. They reported using condoms during sexual intercourse and had no history of sexually transmitted infection (STI). Furthermore, many of the FSWs exposed to T. pallidum reported having more than 20 sexual partners per month, and had partners from other Brazilian states, but not from other countries. An age over 42 years and a reduced level of education were factors associated with exposure to T. pallidum. Finally, a high rate of exposure to T. pallidum among FSWs in the Brazilian state of Pará (from 2005 to 2007) was detected. In later years, epidemiological studies conducted with FSWs recorded that this rate remained high. Measures to control, treat, and prevent syphilis among FSWs were necessary between 2005 and 2007, and they are still imperative today. Actions related to educational programs and STI control, treatment, and prevention measures contained in Brazilian policies aimed at women's health have not changed the vulnerability scenario of FSWs regarding their exposure to T. pallidum, even after 16 years, and must be reviewed and adapted to the conditions of the Brazilian Amazon.

Ocular syphilis in patients with nonreactive RPR and positive treponemal serologies: a retrospective observational cohort study.

Screening for syphilis increasingly relies on positive treponemal rather than nontreponemal tests (rapid plasma reagin [RPR]). We compared ocular syphilis in patients with nonreactive versus positive RPR. We conducted a retrospective observational cohort study of ocular syphilis treated at two New England hospitals 1996-2021 based on ophthalmologist-diagnosed eye findings and positive treponemal serology, regardless of RPR. We excluded patients with alternative diagnoses. We categorized RPR into nonreactive RPR, low-titer RPR (<1:8), and high-titer RPR (≥1:8) and compared early and long-term response to therapy. Our sample included 115 patients with ocular syphilis (median follow-up 2.5 years): 25 (22%) nonreactive RPR, 21 (18%) low-titer RPR, 69 (60%) high-titer RPR. Compared with nonreactive and low-titer RPR, people with high-titer RPR were younger (mean 47 years, p<0.001), more likely male (93%, p<0.001) and more likely to be living with HIV (49%, p<0.001). People with nonreactive and low-titer RPR were less likely than high-titer RPR to have posterior/panuveitis (32% and 29% versus 75%, p<0.001) or abnormal CSF (26% and 35% versus 75%, p<0.001), and more likely to present with chronic eye findings (20% and 29% versus 1%, p<0.001). In long-term follow up, eye findings improved and did not recur in most patients (62% nonreactive, 68% low-titer, 96% high-titer RPR); improved but recurred in 29%, 11%, and 4%, respectively; and were stable in 10%, 21%, and 0%, respectively. Patients with ocular syphilis and nonreactive RPR are similar to patients with low-titer RPR, and antibiotic therapy is beneficial in most.

A Review of Syphilis Infection in Pediatric Patients

Nearly half of all sexually transmitted infections occur in adolescents and young adults. Among them, syphilis infections are on the rise in the United States. Sexually active adolescents, especially those who do not use condoms consistently or are men who have sex with men, are at particular risk for syphilis infection. With the rise in acquired syphilis infections, the incidence of congenital syphilis has also increased. Syphilis can have a variety of presentations based on infectious stage and central nervous system involvement. Careful physical examination and history can elicit the diagnosis. Screening with a nontreponemal test followed by treponemal testing can confirm the diagnosis, and staging is determined clinically. Testing for all sexually transmitted infections should be pursued because coinfections are common. Penicillin is the first-line treatment for syphilis, and duration of therapy depends on the presence of neurologic symptoms; all infants with possible congenital syphilis should receive treatment. Posttreatment monitoring is essential to confirm successful eradication of syphilis. All sexually active, at-risk patients, including pregnant persons, should be screened for syphilis, and those diagnosed as having syphilis should be counseled on disclosure to partners. Although not often found in a pediatric population, with the increasing incidence of syphilis infections in the United States, pediatric providers should have a low threshold for syphilis screening in adolescents and a high index of suspicion for congenital syphilis in infants.

An Exuberant Case of Ulceronodular-Rupioid (Malignant) Syphilis in an HIV Patient: A Proposal for New Diagnostic Criteria.

We report the case of a 28-year-old male with uncontrolled human immunodeficiency virus (HIV) infection who presented with extensive ulcerated lesions with dark lamellated crusting on his face, torso, and limbs. The patient had a rapid plasma reagin (RPR) titer of 1:512, indicative of syphilis. A skin biopsy revealed granulomata surrounded by lymphocytes, histiocytes, and plasma cells, with spirochetes visible on immunohistochemical staining. The patient's rash resolved with hyperpigmented scarring after penicillin and doxycycline treatment. This severe form of secondary syphilis has been termed malignant syphilis, lues maligna, ulceronodular syphilis, or rupioid syphilis. We propose a single descriptive name for this entity, ulceronodular-rupioid syphilis. In 1969, Fisher proposed criteria for malignant syphilis based on lesion appearance, histopathologic findings, high RPR values, and rapid response to treatment. We found that the Fisher criteria were imprecise with respect to specific histopathologic findings, the quantitation of RPR values, and what constitutes rapid response to treatment. Thus, we examined an additional 74 cases from the literature and propose new diagnostic criteria based on rash appearance, histopathologic characteristics, non-treponemal and treponemal test positivity, and response to therapy. We also found that uncontrolled viremia, and not a low CD4 count, is a major risk factor for ulceronodular-rupioid syphilis in HIV patients.

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.

Evaluation of Serological Tests for the Diagnosis of Syphilis.

Background Syphilis remains a significant public health concern in India. Ensuring the accuracy of diagnostic tests is crucial for effectively managing this disease. Objectives This study aims to assess the detectability of syphilis using commercially available non-treponemal and treponemal tests due to observed discrepancies in test results, which can lead to confusion and anxiety among healthcare providers and patients. Materials and methods We analyzed 2312 serum samples using the rapid plasma reagin (RPR), Treponema pallidum hemagglutination assay (TPHA), enzyme-linked immunosorbent assay (ELISA), and modified TPHA rapid test, interpreting the results according to the manufacturers' instructions. We evaluated the diagnostic accuracy of all four tests. Concordance between the traditional and reverse algorithms was determined by calculating the percentage of agreement and the kappa (κ) coefficient. Results Of the 2312 samples tested, 34 (1.5%) were positive, and 2098 (90.7%) were negative across all four tests. Comparing the test results with clinical diagnosis, TPHA and TP-ELISA showed the highest sensitivity at 96.08%, while RPR demonstrated the highest specificity at 100%. The agreement between the traditional and reverse algorithms was moderate, with a 97.3% agreement and a κ value of 0.53. Conclusion Reliance on a single serological test for syphilis screening presents limitations. A combined approach using both RPR and TPHA tests can more accurately diagnose and confirm syphilis. This combination strategy is cost-effective and relatively simple to implement.

Single-test syphilis serology: A case of not seeing the forest for the trees

Introduction There have been few empirical studies for diagnostic test accuracy of syphilis using a sequence of rapid tests in populations with low prevalence of syphilis such as pregnant women. This analysis describes syphilis test positivity frequency among pregnant women at an antenatal clinic in Zambia using a reverse-sequence testing algorithm for antenatal syphilis screening. Methods Between August 2019 and May 2023, we recruited 1510 pregnant women from a peri-urban hospital in Lusaka, Zambia. HIV positive and HIV negative women were enrolled in a 1:1 ratio. Blood collected at recruitment from the pregnant mothers was tested on-site for syphilis using a rapid treponemal test. Samples that tested positive were further tested at a different laboratory, with rapid plasma reagin using archived plasma. Results Of the total 1,421 sera samples which were screened with a rapid treponemal test, 127 (8.9%) were positive and 1,294 (91.1%) were negative. Sufficient additional samples were available to perform RPR testing on 114 of the 127 (89.8%) RDT positive specimens. Thirty-one (27.2%) of these 114 were reactive by RPR and 83 (72.8%) were negative, resulting in a syphilis overtreatment rate of 3 fold (i.e, 84/114). Insufficient sample or test kit availability prevented any testing for the remaining 89 (5.9%) participants. Conclusion Use of only treponemal tests in low prevalence populations, like pregnant women, subjects individuals with non-active syphilis to the costs and possible risks of overtreatment. The use of the dual treponemal and non-treponemal tests would minimize this risk at some additional cost.

Syphilitic Unorthodoxy: A Case of Lues Maligna in a Human Immunodeficiency Virus-negative 28-year-old Filipino Male

Lues maligna, also known as malignant syphilis, is an uncommon variant of syphilis at the secondary stage – more commonly reported in immunocompromised patients or those with concomitant human immunodeficiency virus (HIV) infection. In this report, we present a case of a 28-year-old HIV-negative male with a 9-month history of multiple, well-defined, irregularly-shaped, erythematous papules, and small plaques evolving to ulcerated plaques and nodules with crusts, associated with pain, pruritus, and episodes of fever, arthralgia, and weight loss. Positive treponemal and nontreponemal tests, aided by histopathologic findings consistent with syphilis led to the diagnosis of lues maligna. Significant improvement of lesions was noted with 3 weekly doses of 2.4 million units of benzathine penicillin G. For patients presenting with painful and pruritic erythematous ulcerated plaques with crusts associated with systemic symptoms, and with a significant sexual history despite testing negative for HIV infection, a high index of suspicion for uncommon presentations of other sexually transmitted infections such as syphilis could aid in early diagnosis and subsequent treatment.

Development of toluidine red particle agglutination-based turbidimetric immunoassay for anticardiolipin antibody detection in syphilis

IntroductionSerological tests of non-treponemal and treponemal types are the most frequently used for syphilis diagnosis. Nontreponemal tests are used to monitor disease activity. Toluidine red unheated serum test (TRUST), as one of nontreponemal tests, is generally applicable to hospitals at different levels. However, accurate judgment of TRUST results is inseparable from an experienced and accurate operator. To reduce current shortcomings of manual TRUST method, we attempted to convert the manual TRUST test into automatic TRUST test, that is, to determine the degree of aggregation of toluidine red particles by detecting the absorbance value of serum after reaction with toluidine red particles. Methods50 μL of serum sample and 80 μL toluidine red particles were added to 96-well plate. Then, the 96-well plate was placed on a microplate reader at medium grade for 8 min to mix. Then, plasma reagin reacted with toluidine red particles and promoted the aggregation of toluidine red particles to form a large clot, which eventually caused a decrease in the absorbance at 540 nm. ResultsThe results showed that the specificity of the automatic TRUST test was 100%, the sensitivity was 87%. And this method showed 93.5% correlation with manual TRUST test. The developed method is simple and involves less subjectivity in reading results, opening new avenues for syphilis diagnostic testing. ConclusionTurbidimetric immunoassay can avoid the shortcomings of subjective interpretation, time-consuming and manual operation of manual TRUST method, and is more suitable for large-scale screening in health examination.

Insights into ocular syphilis in Nepal.

This study aims to elucidate the demographic characteristics, clinical features, diagnostic approaches, and medical management of patients with ocular syphilis, known as 'the great masquerader,' at a tertiary eye care center in Nepal. We conducted a retrospective review involving 15 eyes from ten patients with ocular syphilis treated at a uveitis referral center between 2020 and 2022. Lumbar puncture was performed if neurosyphilis was suspected. Treatment success was defined as the absence of ocular inflammation in both eyes and a decrease in Veneral disease research laboratory (VDRL) titres after completing therapy. A total of 15 eyes of 10 patients were diagnosed with syphilitic uveitis based on positive treponemal and non-treponemal serological tests. The mean age of the patient was 39.9years (range 22-54years) with an equal distribution between males and females. HIV coinfection was not found in any of the patients. Syphilitic uveitis was the primary presentation in nine patients (90%), while one patient presented with recurrent nodular scleritis. Ocular involvement was bilateral in 50% (5 patients). The mean duration between the initial symptom and the first presentation was 8.7weeks (range: 4days to 24weeks). The most common ocular findings was panuveitis (6 eyes). Eight patients with early syphilis received weekly intramuscular injections of benzathine penicillin G for 3 weeks whereas 2 patients with neurosyphilis were treated with intravenous ceftriaxone 1 gm twice a day for 14 days. Signs and symptoms of majority of patients improved with systemic therapy for syphilis. Syphilitic uveitis should be included in the differential diagnosis of any form of ocular inflammation.

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.

Low genetic diversity of Treponema pallidum ssp. pertenue (TPE) isolated from patients' ulcers in Namatanai District of Papua New Guinea: Local human population is infected by three TPE genotypes.

Yaws is an endemic disease caused by Treponema pallidum subsp. pertenue (TPE) that primarily affects children in rural regions of the tropics. The endemic character of yaws infections and the expected exclusive reservoir of TPE in humans opened a new opportunity to start a yaws eradication campaign. We have developed a multi-locus sequence typing (MLST) scheme for TPE isolates combining the previously published (TP0548, TP0488) and new (TP0858) chromosomal loci, and we compared this typing scheme to the two previously published MLST schemes. We applied this scheme to TPE-containing clinical isolates obtained during a mass drug administration study performed in the Namatanai District of Papua New Guinea between June 2018 and December 2019. Of 1081 samples collected, 302 (28.5%) tested positive for TPE DNA, from which 255 (84.4%) were fully typed. The TPE PCR-positivity in swab samples was higher in younger patients, patients with single ulcers, first ulcer episodes, and with ulcer duration less than six months. Non-treponemal serological test positivity correlated better with PCR positivity compared to treponema-specific serological tests. The MLST revealed a low level of genetic diversity among infecting TPE isolates, represented by just three distinct genotypes (JE11, SE22, and TE13). Two previously used typing schemes revealed similar typing resolutions. Two new alleles (one in TP0858 and one in TP0136) were shown to arise by intragenomic recombination/deletion events. Compared to samples genotyped as JE11, the minor genotypes (TE13 and SE22) were more frequently detected in samples from patients with two or more ulcers and patients with higher values of specific TP serological tests. Moreover, the A2058G mutation in the 23S rRNA genes of three JE11 isolates was found, resulting in azithromycin resistance.

Factors influencing the positivity of diagnostic tests for congenital syphilis.

The objective of this study was to analyze the factors that influence the positivity of treponemal and non-treponemal tests in cases of congenital syphilis. This cross-sectional and correlational study was carried out from the analysis of the database of Disease and Notification Information System (SINAN, in Portuguese) using the data obtained through the Epidemiological Surveillance Group 29, with 639 notifications of congenital syphilis between 2007 and 2018. The data were analyzed by a descriptive and inferential analysis from logistic regression with a significance level of 5% (p≤0.05). The positivity of the treponemal test was higher by 4.5 times in infants living in rural areas and 19.6 times among those whose mothers obtained the diagnosis of syphilis after birth. The treponemal test showed positivity 3.2 times higher for the variable "having been diagnosed between 2007 and 2015" and 5.5 times higher for the variable "having been diagnosed with maternal syphilis in the postpartum period." This study shows that testing during prenatal care is essential for early diagnosis and prevention of syphilis complications.

Syphilitic Chorioretinitis – two case Reports and Literature Analysis

IntroductionSyphilis, a systemic, sexually transmitted inflammatory disease caused by Treponema pallidum, presents challenges in diagnosis due to its varied manifestations. Ocular syphilis often presents with non-specific symptoms. This study aims to elucidate the diagnostic process through the analysis of two patient cases, including one with HIV co-infection.Material and MethodsThe study evaluated two ocular syphilis cases, diagnosed using comprehensive treponemal (fluorescent treponemal antibody absorption test, Treponema pallidum hemagglutination assay, enzyme immunoassay) and nontreponemal (venereal disease research laboratory test, rapid plasma reagin test) testing. Factors such asuveitis symptoms, sexual behavior, drug use, previous treatments, and available medical history were considered.ResultsThe results highlight the complexity of ocular syphilis diagnosis. Both cases underscored the need to include ocular syphilis in differential diagnoses for eye infections or inflammations, especially in patients with high-risk behaviors, drug use, or a history of syphilis. The non-specific nature of symptoms necessitates comprehensive testing for accurate diagnosis.ConclusionsThis study reinforces the importance of considering ocular syphilis in the differential diagnosis of inflammatory eye diseases. A meticulous approach combining both treponemal and nontreponemal tests is crucial for accurate diagnosis. These findings emphasize the need for thorough clinical evaluation and history-taking in patients presenting with ocular symptoms.

Current Diagnosis Pathway of Syphilis: An Update

Syphilis is a multifaceted contagious disease caused by Treponema pallidum, a spiral-shaped bacterium that can infect practically any organ or tissue in the body and result in a wide range of clinical symptoms. The purpose of this paper is to provide a comprehensive overview of the current diagnostic process for syphilis. The progression of acquired syphilis is typically categorized into two primary phases: early (infectious) syphilis and late syphilis. Traditional screening algorithms employ treponemal tests to validate positive nontreponemal testing. Due to its high sensitivity, particularly in the advanced stages of the illness, treponemal testing is valuable in cases where there are clinical indications of syphilis, but nontreponemal serologic testing for syphilis yields negative results. The treponemal tests yielded positive results in a significant number of patients diagnosed with primary syphilis and in nearly all patients diagnosed with secondary syphilis.

A-315 Pregnant Women Showed Lower Incidence Rates of False-positive Treponemal Antibody Screening Results When Compared with Nonpregnant Women and Men at an Appalachian Academic Medical Center

Abstract Background Screening for syphilis infection is recommended for all pregnant women and any adult or adolescent with increased risk for infection. Many clinical labs have adopted the reverse syphilis serology testing algorithm, that employs an automated and high-throughput treponemal antibody test as the initial screen followed by a non-treponemal antibody test to confirm all reactive samples. For specimens with discordant results, a second treponemal antibody test is used as the adjudicator. Syphilis serological tests can have false-positive results, causing discordant results between screening test and confirmatory test and complicating result interpretation. It is controversial from the literature whether pregnancy is a cause of false-positive results. This study is to determine the incidence rate of false-positive treponemal screening results among pregnant and nonpregnant patients, and to assess whether false-positivity is associated with pregnancy and age. Methods This is a retrospective study of sequential results from two treponemal antibody screening tests, including BioPlex 2200 Syphilis Total immunoassay between May 2020 and Jan 2022, and Alinity i Syphilis TP assay between Feb 2022 and Nov 2022. For each screening test, the incidence rates of false-positive results were calculated based on the reverse algorithm criteria and compared among pregnant women, nonpregnant women and men. The age differences between patients with false-positive results and patients with nonreactive results were also evaluated. Results Overall, 0.32% of 9 575 samples tested by Alinity assay showed false-positive results not confirmed by RPR or TP-PA. This is significantly lower (P &amp;lt; 0.01) than 0.60% of 14 983 samples observed for BioPlex assay. However, the lower incidence rate of false-positive results for Alinity assay relative to the Bioplex assay is only observed in pregnant women (0.18% vs 0.44%, P &amp;lt; 0.01) and nonpregnant women (0.32% vs 0.71%, P = 0.06), but not in men (0.68% vs 0.63%, P = 0.81). For both assays, male patients with false-positive results had an older median age than those with nonreactive results, and female patients showed the opposite trend, although statistical significance was only observed in nonpregnant women for Bioplex assay (median [IQR], 25 [19–35] vs 30 [22–43], P = 0.047). For both assays, pregnant women had lower incidence rates of false-positive results than nonpregnant women, although the differences did not reach statistical significance without age adjustment (Bioplex assay: 0.44% vs 0.71%, P = 0.07; Alinity assay: 0.18% vs 0.32%, P = 0.26). When age is adjusted, binary logistic regression analysis showed that pregnant women had significantly lower incidence rates of false-positive results relative to nonpregnant women for both assays (BioPlex assay: P = 0.049; Alinity assay: P &amp;lt; 0.01). Conclusion Although the incidence rates of false-positive results in BioPlex and Alinity treponemal antibody screening tests were overall within a low range, a significantly lower rate was observed for Alinity assay in pregnant women but not in men. For both assays, pregnant women showed a significantly lower incidence rate of false-positive results in comparison with nonpregnant women after age adjustment.

A-180 A Retrospective Review of Syphilis Serology Interpretation Accuracy

Abstract Background Syphilis is a sexually transmitted disease caused by the spirochaete bacterium Treponema pallidum. It is acquired through direct contact, is highly infectious and can survive in an untreated host for years. Multiple tests are available for diagnosis and broadly classified as treponemal and nontreponemal. Treponemal tests are used to detect T. pallidum particles and antibodies and the nontreponemal tests include the rapid plasma regain (RPR). Due to this complexity, interpreting syphilis serology tests are a common cause of questions to clinical consultants and have the potential for incorrect diagnosis. Because of this we initiated a retrospective review of past positive serology results to assess provider accuracy in interpreting these tests. Methods The study cohort was composed of 108 patients from July—December 2021 that had at least one positive serology test. The assays used were the Syphilis Total Antibodies and RPR assays and both were performed in-house. The clinical history of each patient was reviewed to obtain relevant data pertaining to the diagnosis. This information included the age, gender, additional send out confirmatory testing, previous history of syphilis, provider type and specialty who ordered the tests. The interpretation by the clinicians was also determined and whether they prescribed antibiotics. Statistical analysis was performed to assess what patient and provider characteristics were associated with a correct or incorrect interpretation of the syphilis test results. This study was approved by the institutional IRB. Results The study cohort showed that 12/108 (11.1%) positive results were interpreted incorrectly. The comparison of correct vs incorrect interpretation was insignificant across most of the variables, including age, gender, diagnosis and provider type. However, in relation to provider specialty the comparison was significant with a P-value of 0.003. This was due to a high percentage of incorrect interpretations obtained from family medicine providers, reaching roughly 50% of total incorrect interpretations. Empirically, questions to the Pathology laboratory concerning syphilis results interpretation have also been observed more often among the family medicine providers. Additionally, providers from infectious disease, internal medicine and OB/GYN composed 54.3% of the providers in our study and only had one interpretation error indicating very high accuracy. Conclusion Overall, the study demonstrated a significant number of incorrectly interpreted syphilis results, with the majority occurring among the family medicine providers. Assistance with interpretation of syphilis results is one of the most frequently asked questions received at the Pathology laboratory. Appropriate education, in particular for the family medicine providers, will assist in addressing this issue, as well as implementing additional resources to the electronic medical record that can be linked to the reported syphilis results. The distinction of a true positive diagnosis from a false one is important for proper patient care, preventing the treatment of patients who don’t need it and allowing for the timely treatment of those who do.