Nontreponemal Antigen Research Articles

False Negative Results of First-Tier Treponemal Antibodies in an HIV-Infected Patient

Abstract Introduction/Objective Syphilis diagnosis relies on detecting Treponema pallidum antibodies in serum or CSF. In the reverse syphilis screening algorithm, an automated enzyme immunoassay first detects serum antibodies against treponemal antigens. A negative result halts further testing; however, a positive result prompts manual testing for antibodies against non-treponemal antigens such as cardiolipin. The sensitivity of first-tier automated assays is typically high. We present a case of an HIV patient who initially tested negative for syphilis in the first-tier assay but was subsequently diagnosed with the infection. Methods/Case Report A 30-year-old HIV-positive female (CD4+ count 24/mm3), previously diagnosed with chlamydia and gonorrhea, experienced blurred vision, eye pain, fever, and a palmoplantar rash. Despite clinical suspicion of syphilis, the initial first-tier chemiluminescence immunoassay (CIA) for treponemal antibodies (LIAISON Treponema, DiaSorin, Stillwater, MN) returned a negative result, precluding any further syphilis testing at that time. However, a skin biopsy revealed interface dermatitis and spirochetes. CSF analysis showed pleocytosis, increased proteins, and borderline low glucose, with both VDRL and IFA assays negative. Based on these findings, we retested for serum antibodies by repeating the CIA test and performing RPR and TP-PA assays outside the algorithm sequence. Despite reconfirmation of the CIA negativity, both RPR (titer 1:64) and TP-PA were positive, leading to a secondary syphilis diagnosis and penicillin G treatment. Subsequent investigations aimed to explain the initial false negative CIA result. Serial dilution of the patient's serum up to 1:1000 did not alter the result, excluding the 'hook effect' caused by an excessive concentration of antibodies. Further serum testing at a different laboratory using another type of first-tier immunoassay yielded a positive result, pointing toward differences in the composition of treponemal antigens utilized across various manufacturer assays as the likely cause of the discrepancy. Results (if a Case Study enter NA) NA Conclusion Given their high sensitivity, automated first-tier treponemal assays rarely yield false negative results, whereas false positives are the most common ‘lab error’ and are typically resolved with second-tier assays. Nevertheless, this case highlights that false negatives can occur and, thus, stresses the need to re-evaluate the approach in diagnosing syphilis, especially in patients with antibody production abnormalities, such as those with HIV.

Evaluation of False Positive RPR Results and the Impact of SARS-CoV-2 Vaccination in a Clinical Population with a High Rate of Syphilis Utilizing the Traditional Screening Algorithm

Abstract Background Syphilis infection caused by the bacterium Treponema pallidum is a sexually transmitted infection leading to serious health complications if undiagnosed or untreated. Serologic diagnostic methods include a combined approach for detection of antibodies to non-treponemal (RPR) and treponemal antigens using a traditional or reverse algorithm. The BioPlex2200 Syphilis Total/RPR assay (BioRad Laboratories) is an automated method for simultaneous detection of treponemal/non-treponemal antibodies, but recently recalled due to potential RPR false reactivity following SARS-CoV-2 mRNA vaccination. The purpose of this study was to evaluate syphilis confirmation and false positive RPR rates over various intervals preceding and during the COVID-19 pandemic in a population with a high rate of syphilis, and a subset of pregnant females screened for syphilis prior to delivery, to assess the impact of mRNA vaccines on different RPR reactivity rates and methodologies. Methods The study cohort included all individuals screened for syphilis (n=48,288) and a subset of pregnant patients (n=2,944), where syphilis testing was ordered for routine clinical care utilizing the traditional algorithm. Five timepoints represented various phases and RPR methods utilized throughout the pandemic: 1) pre-COVID-19 (automated RPR, July – December, 2019); 2) COVID-19, pre-mRNA vaccine (manual RPR, July – December, 2020); 3) COVID-19, mRNA vaccine (manual RPR, January – June, 2021); 4) COVID-19, mRNA vaccine/boosters (automated RPR, August – December, 2021); and 5) COVID-19, mRNA vaccine/boosters (RPR/T.pallidium sent out to reference laboratory, January – February, 2022). False positive RPR was defined as reactive RPR/nonreactive T.pallidium. Titers were determined for all reactive RPR specimens. Results Syphilis confirmation rates were between 4.5 – 7.9% for all patients and 0.15 – 0.41% for pregnant patients during the entire study period. False positive RPR rates increased in the screening (5% to 8.6%) and pregnant groups (4.4% to 7.5%) from 2019 to 2021. Comparing only timepoint 1 (2019) to timepoint 4 (end of 2021), both reporting automated RPR, overall reactivity rates increased from 8.2% to 14.1% in the screening cohort and 4.8% to 7.8% in the pregnant cohort. No significant differences were observed in manual RPR reactivity (5.2% vs. 6.3%) or false positive rates (1.3% vs. 1.2%) pre- and post-vaccination in the screening or pregnant population (reactivity rates: 0.68% vs. 0.29%; false positives: 0.27% vs. 0.15%). Over 90% of RPR false positives had titers less than 1:4. False positive RPRs decreased from 8.6% to 2.9% following implementation of RPR sendouts. Conclusions RPR false reactivity rates increased with SARS-CoV-2 vaccination but is specific to the BioPlex2200 RPR assay which has improved analytical sensitivity for anti-lipoidal antibodies compared to manual RPR methods, thus may be more susceptible to false positives post-vaccination. Increased RPR reactivity rates were clinically notable likely because the traditional syphilis screening algorithm is utilized at our institution.

Yaws elimination in Ecuador: Findings of a serological survey of children in Esmeraldas province to evaluate interruption of transmission.

The WHO roadmap for neglected tropical diseases includes yaws eradication requiring certification of elimination of transmission in all endemic and formerly endemic countries worldwide. A community-based programme for yaws control was considered to have achieved elimination of the infection in the endemic focus in Ecuador after 1993. We did a serosurvey of children in this focus to provide evidence for interruption of transmission. Survey of serum samples collected from children aged 2 to 15 years living in the formerly endemic and in geographically contiguous areas. A convenience sample of sera collected between 2005 were 2017 from non-yaws studies, were analyzed using immunochromatic rapid tests to screen (OnSite Syphilis Ab Combo Rapid Test) for Treponema pallidum-specific antibodies and confirm (DPP Syphilis Screen and Confirm) seroreactivity based on the presence antibodies to treponemal and non-treponemal antigens. Seroreactivity was confirmed in 6 (0.14%, 95% CI 0.06-0.30) of 4,432 sera analyzed and was similar in formerly endemic (0.11%, (95% CI 0.01-0.75) and non-endemic (0.14%, 95% CI 0.06-0.34) communities. All seroreactors were of Afro-Ecuadorian ethnicity and most were male (4/6) and aged 10 or more years (5/6), the latter possibly indicating venereal syphilis. Only 1 seroreactor lived in a community in the Rio Santiago, that was formerly hyperendemic for yaws. We observed very low levels of treponemal transmission in both formerly endemic and non-endemic communities which might be indicative of congenital or venereal syphilis and, if yaws, would likely be insufficient to maintain transmission of this endemic childhood infection. Additional surveys of children aged 1 to 5 years are planned in Rio Santiago communities to exclude yaws transmission.

Canadian Public Health Laboratory Network guidelines for the use of point-of-care tests for Treponema pallidum in Canada.

Over the past few years, the increase in infectious syphilis outbreaks in major urban centres and remote or rural locations in Canada, often affecting hard-to-reach patient populations, has renewed an interest and urgency in studying the use of point-of-care tests (POCTs) that can provide test results at the time and place of primary health care delivery, obviating the repeat visit necessary with traditional syphilis serology or molecular diagnostic tests. In 2015, the Canadian Public Health Laboratory Network released its first laboratory guideline for the use of POCTs in the diagnosis of syphilis in Canada. Although Canada has no licensed POCT, two POCTs (Syphilis Health Check and the DPP® HIV Syphilis System) have received US Food and Drug Administration (FDA) approval under premarket approval applications. Most syphilis POCTs detect antibodies to treponemal antigens, so their results cannot be used to differentiate between active and past infection. The only POCT that detects antibodies to both treponemal and non-treponemal antigens does not yet have Health Canada or FDA approval. In this updated guideline, the current landscape of POCTs for syphilis, with an emphasis on data from low-prevalence countries, is described. Individual operators should consider the questions of where, when, how, and why a POCT is used before its actual implementation. Training in the operation and interpretation, quality control, proficiency program, safety, and careful documentation of the process and results are especially important for the successful implementation of POCTs.

Immunization with nontreponemal antigen alters the course of experimental syphilis in the rabbit model

The role of nontreponemal antibodies in the Treponema pallidum infection course is unclear. We investigated the effect of immunization with nontreponemal antigen on T. pallidum-challenged rabbits. Nontreponemal antigen was injected intravenously into rabbits in the nontreponemal group (n = 12) to elicit antibodies (≥1:64), and normal saline-injected rabbits were used as controls (n = 12). Then, rabbits were challenged with 106T. pallidum per site along their back. Lesion development was observed, and the injection sites were biopsied for mRNA analysis every week. Six rabbits from both groups were euthanized at 14 d and 28 d. The popliteal lymph nodes were extracted to assess infectivity using a rabbit infectivity test. The maximum lesion diameters were not different between the two groups (12.4 ± 0.9 mm in the nontreponemal group vs. 12.5 ± 1.0 mm in the control group, P = 0.386), but the time to maximum diameter appearance was delayed by approximately 4 d in the nontreponemal group (14.4 ± 1.6 d vs. 10.8 ± 1.9 d, P = 0.000). There were no significant differences in the proportions of lesions (58/60 (96.7%) vs. 59/60 (98.3%), P = 0.500) or ulcers (55/60 (91.7%) vs. 57/60 (95.0%), P = 0.359) between the two groups. An ulcer development delay of 5 d was observed in the nontreponemal group (19.3 ± 2.0 d vs. 14.0 ± 1.8 d, P = 0.000). IL-2 and IFN-γ mRNA expression in the nontreponemal group was significantly higher than that in the control group at 7 d and 14 d post-challenge. flaA mRNA expression and the rabbit infectivity test positive rate were not different between the two groups. Immunization with nontreponemal antigen altered the syphilis course in rabbits, resulting in delayed maximal lesion diameter and ulcer development, but it could not inhibit the spread of T. pallidum from primary lesion sites to viscera.

A clinical audit of maternal syphilis in a regional hospital in KwaZulu-Natal, South Africa

BackgroundDespite the availability of screening guidelines and effective treatment for maternal syphilis (MS), its prevalence remains high and is re-emerging in many parts of the world. This might be because of varying screening tests and algorithms for the laboratory diagnosis and treatment of syphilis. In addition, HIV co-infection may compromise the elimination of MS. The present study is a clinical audit of the prevalence of MS in KwaZulu-Natal, South Africa, using the ‘Traditional Algorithm’ screening.MethodsThis was a retrospective audit in which data on syphilis testing were obtained over a 1-year period (2016) at a large regional hospital in South Africa. The standard screening test at the study site was the non-treponemal antigen, rapid plasma reagin (RPR). Data on the prevalence of MS and comorbidity with HIV infection were analysed.ResultsThere were 10 680 deliveries in the study period of which 118 were RPR reactive, giving an MS prevalence of 1.1%. MS occurred predominantly in the age groups < 18 and > 35 years (p = 0.001). The prevalence of HIV infection was 41.2% (n = 4451). Seventy-two (61.0%) had both HIV and MS infection, whilst 46 (39.0%) had discordant results (p = 0.001).ConclusionWe report an increase in the prevalence of MS compared to previous South African National Antenatal Syphilis Surveillance studies. This may be because of the prozone effect caused by HIV infection on the sensitivity of the RPR. We propose a change in MS screening, using a Rapid DUO (Dual HIV and syphilis point of care test) and Reverse Algorithm for screening that could improve the sensitivity, detection and management of both diseases.

Differential influence of race and environment on indeterminate reactivities to non-treponemal and treponemal antigens by immuno-chromatographic dual syphilis rapid test.

IntroductionSyphilis rapid test results may be influenced by numerous environmental and genetic factors.MethodsThe proportion of false positive syphilis non-treponemal (NT) and treponemal (T) test results using immuno-chromatographic dual syphilis rapid test on serum from Cameroonian blacks (n=103) versus French blacks (n=104) or French caucasians (n=51), all HIV-negative and free of clinical syphilis, was examined.ResultsBlack individuals in Cameroon had a significantly higher frequency of false positive NT or T tests than black individuals in France. black individuals in France had a higher frequency of indeterminate NT tests as compared to caucasians in France.ConclusionBoth racial and environmental factors may affect immuno-chromatographic dual syphilis rapid testing.

Canadian Public Health Laboratory Network laboratory guidelines for the use of point-of-care tests for the diagnosis of syphilis in Canada.

Syphilis point-of-care tests (POCT) are widely available in developing countries enabling early diagnosis, treatment and support. The majority of commercially available tests use treponemal antigens and the presence of antibodies does not distinguish between current and past infection, which may lead to unnecessary antibiotic use and stigmatization of having a current STI. In hard-to-reach populations, the benefits may outweigh the risks. Available studies show reasonable performance of POCT with median sensitivity of 86%, specificity of 99% and positive predictive values >80% when prevalence was >0.3%. Although no syphilis POCT are approved in Canada at this time, a single study in an outreach setting in Alberta showed limited benefit due to a high prevalence of previous infection but more studies are needed. Newer dual tests employing treponemal and nontreponemal antigens look promising.

A Fatal Fall Associated With Undiagnosed Parenchymatous Neurosyphilis

A fall from a great height is often associated with altered mental status. Aside from the usual contributing factors, for example, alcohol consumption or mental illness, natural disease leading to a fatal fall is seldom identified by autopsy. The case described in this report is that of a 57-year-old man who had been clinically diagnosed with presenile Alzheimer disease and fell head first into a river from the bridge. These events were captured by a surveillance camera on the bridge; an acquaintance reported that he had previous suicidal ideation. At autopsy, the cervical spinal cord was determined to have been severely injured, and the sixth cervical vertebra was observed to have been fractured. Histological examination showed chronic meningoencephalitis including neuronal loss, perivascular cuffing, and the proliferation of microglia and astrocytes in the cerebral cortex. Serologic evaluation consisting of the nontreponemal antigen test (rapid plasma reagin [RPR]) and treponemal antibody test (Treponema pallidum latex agglutination) was positive in both cases (RPR: 18.2 RPR units, T. pallidum latex agglutination: 7718 U/mL). These findings suggested that the patient had been affected by a syphilis infection and that his suicidal behavior was associated with parenchymatous neurosyphilis.

O15.3 Evaluation of an Immunochromatographic Point-Of-Care Test For the Simultaneous Detection of Nontreponemal and Treponemal Antibodies in Patients with Syphilis

BackgroundWe described the evaluation of the DPP Syphilis Screen and Confirm Assay, a point-of-care test (POC) for the simultaneous detection of nontreponemal and treponemal antibodies for the serological diagnosis of patients with syphilis.MethodsA total of 248 samples from patients with active syphilis (173), past syphilis (15) and from individuals considered as no infected byTreponema pallidum(60) were studied with the DPP Syphilis Screen and Confirm, Rapid Plasma Reagin (RPR), and fluorescent treponemal antibody absorption (FTA-Abs) tests. In addition patients with active syphilis cases (36) primary, (39) secondary, and (98) latent, were evaluated. The DPP Syphilis Screen and Confirm device consists of a plastic cassette with a recombinantT. pallidumand a synthetic nontreponemal test line antigens and a procedural control line.ResultsThe sensitivity of the DPP Syphilis Screen and Confirm, nontreponemal and treponemal tests was 97.6% and 96.8% while the specificity was 94.7% and 93.1% respectively, when compared to the predicates RPR and FTA-abs tests. The treponemal and nontreponemal clinical sensitivity of primaries was 100% (36/36), for both and for secondary syphilis was also 100% (39/39), for both test and predicates. For patients with latent syphilis the sensitivity was 97.96% (96/98) for the treponemal test and 98.98% (97/98) for the nontreponemal test while for the predicates FTA-ABS and RPR was 100% (98/98) and 98.98% (97/98), respectively. With patients without syphilis the specificity of the DPP Syphilis Screen and Confirm test was 91.66% (55/60) for the treponemal line and 96.66% (58/60) for the nontreponemal line.ConclusionThese results indicates that the DPP Syphilis Screen and Confirm POC test could be a useful tool for the serological diagnosis of syphilis, including resource-poor settings where there is a need to provide counselling and treatment on site and thus prevent the further spread of the disease.

Reformation and evaluation of an operating procedure for detecting syphilitic anticardiolipin reagin

Objective To estimate the application value of a standard operating procedure (SOP) in the detection of syphilitic anticardiolipin reagin. Methods Clinical laboratories from 9 local hospitals in Shanghai participated the program. Quality control samples with unknown target value were qualitatively and quantitatively examined according to the uniform SOP in these laboratories with the same reagent and facility of horizontal reaction. External quality assessment (EQA) was carried out by using seven serum samples with no, or low (1∶ 128 dilution) to high (1∶1 dilution) concentrations of target before and after the implementation of SOP. The test results were statistically analyzed and the reasons for the detecting error were assessed. Results A total of 388 tests were performed in the 9 clinical laboratories. The total accuracy rate was 93.0%, including 40.2% in the detection of samples with 1 ∶ 8 dilution of target, 49.2% in the detection of samples with 1 ∶ 16 dilution of target, and 3.6% in the detection of samples with 1 ∶ 32 dilution of target. No forward bias was observed in these tests. There was a significant difference in the accuracy rate between the two times of EQA before and after the implementation of SOP (x2 = 4.17, P < 0.05). Conclusions The improved standard procedure for nontreponemal antigen test is beneficial to the decrease of testing error, and may provide a basis for the establishment of SOP and implementation of internal quality assessment. Key words: Syphilis serodiagnosis; Reference standards; Quality assurance

Screening for congenital syphilis with TPPA and TRUST in 7800 neonates

Objective To assess the value and clinical applicability of non-treponemal antigen serologic test and Treponema pallidum antigen serologic test in the diagnosis of congenital syphilis. Methods Totally,7800 newborns were collected from the out-patient and in-patient department. Toluidine red unheated serum test (TRUST) was conducted to quantitatively detect non-treponemal antibodies and Treponema pallidum particle agglutination assay (TPPA) to qualitatively detect specific treponemal antibodies in these subjects. The results of first serology test for syphilis were assessed for neonates with confirmed congenital syphilis. The sensitivity and specificity in the diagnosis of congenital syphilis were compared between TPPA and TRUST.Results Of the 7800 newborns undergoing syphilis serology testa, 60 were positive for TPPA and TRUST,including 15 cases of congenital syphilis, 47 were positive for TPPA but negative for TRUST, including 5 cases of congenital syphilis. The sensitivity and specificity were 75% (5/20) and 99.41% (7734/7780) respectively for TRUST in the diagnosis of congenital syphilis, 100% (20/20) and 98.88% (7693/7780) respectively for TPPA. Conclusion TPPA seems more applicable than TRUST to the screening for congenital syphilis.

Lipid removal from human serum samples.

The efficacy of lipid removal from human serum samples obtained by using Cleanascite HC, a commercially available product, was compared to that obtained by the standard chloroform method. Separate samples of 21 frozen, banked human serum samples used in the preparation of samples for proficiency testing were treated with either Cleanascite HC or chloroform. The lipid content was measured before and after treatment. The total percentages of lipid removed ranged from 61 to 70% with Cleanascite HC and from 60 to 62% with chloroform. The advantage of Cleanascite HC over chloroform is based on the simplicity of the procedure with Cleanascite HC without the environmental concerns inherent in the use of chloroform. In 15 serum samples known to contain antibodies to treponemal and nontreponemal syphilis antigens, Cleanascite HC bound some immunoglobulin, but with only minimal loss of reactivity in the serologic tests for syphilis. Cleanascite HC is therefore an acceptable alternative to chloroform for lipid reduction in human serum samples.

Syphilis serology and HIV infection in Harare, Zimbabwe.

OBJECTIVE: To determine the reliability of serological tests in detecting syphilis in a factory worker cohort and examine the impact of concurrent HIV infection on serological tests for syphilis. METHOD:...

Enzyme-linked immunosorbent assays for detection of immunoglobulin M to nontreponemal and treponemal antigens for the diagnosis of congenital syphilis.

Sera from newborn infants born of mothers with a high risk of syphilis were examined for immunoglobulin M (IgM) antibodies in two different enzyme-linked immunosorbent assays (ELISAs), using either purified flagella from Treponema phagedenis biotype Reiter or the Venereal Disease Research Laboratory (VDRL) antigen as the antigen. All sera were also examined by the fluorescent treponemal antibody absorption (FTA-ABS) test for IgM. Three different groups of patients were studied. Group 1 consisted of 84 women and their newborn infants from a high-risk population for syphilis. Congenital syphilis was diagnosed in one child who had an IgM-positive cord blood specimen in both the ELISA and the FTA-ABS test. Group 2 consisted of 10 mothers and their newborn children. All mothers had positive syphilis-screening tests, and all children had signs of congenital syphilis. All but one child had positive IgM tests. Group 3 consisted of 15 mothers and their newborn children. These mothers had been treated for syphilis late in pregnancy, and all had a positive screening test at delivery. Two of the children had positive IgM tests, probably caused by reactivity after late intrauterine treatment of congenital syphilis. The specificities of the IgM tests were high when evaluated with sera from newborn children without signs of congenital syphilis. Even though IgM rheumatoid factor was found in all of the children tested with definite congenital syphilis, the rheumatoid factor did not cause false-positive results in either the VDRL ELISA or the flagellum ELISA. No significant IgG-IgM competition was noticed in the ELISAs. This study also confirmed that IgA antibodies do not cross the placenta; most newborn children with congenital syphilis were positive in the VDRL ELISA for IgA. Both the VDRL ELISA and the flagellum ELISA are very useful in the diagnosis of congenital syphilis and may be substitute for the FTA-ABS test. The VDRL ELISA for IgM will be especially useful in developing countries with a high incidence of congenital syphilis.

Correlation of positive syphilis serology with invasive amebiasis in Japan.

Approximately 20% of 52 Japanese males with invasive amebiasis confirmed by gel diffusion precipitin test (GDP) were positive by both Treponema pallidum hemagglutination test (TPHA) and nontreponemal antigen tests, and an additional 20% were positive by TPHA alone. However, none of 109 GDP-negative Japanese males without invasive amebiasis were positive on these serologic tests for syphilis. At least 2 bisexuals and 4 homosexuals were among those with invasive amebiasis. All of these biased males were positive on both TPHA and nontreponemal antigen tests. Four of the biased males had liver abscess and 2 had amebic dysentery or colitis. Bisexual or homosexual males were not found in the negative GDP group. These observations suggest that sexually transmitted amebiasis due to Entamoeba histolytica occurs among sexually biased males in Japan.

Toluidine red unheated serum test, a nontreponemal test for syphilis.

We have shown that a modification of the color-coded antigen developed by Kasatiya and Lambert (Appl. Microbiol. 28:317-318, 1974) can be used as a substitute for other nontreponemal antigens used in screening tests for syphilis. The antigen is based on the Venereal Disease Research Laboratory antigen, with EDTA, choline chloride, and toluidine red toner added. Performance of the toluidine red unheated serum test (TRUST) is identical to that of the rapid plasma reagin 18-mm circle card test (U.S. Department of Health, Education, and Welfare, Public Health Service Publication no. 411). In a series of preliminary evaluations, the TRUST antigen was found to be stable over a period of 6 months at 4 degrees C. In a comparison of TRUST with the rapid plasma reagin card test, the qualitative agreement was 100%, whereas agreement between these two tests and the Venereal Disease Research Laboratory slide test was 99.7%. The quantitative agreement +/- 1 twofold dilution between TRUST and the rapid plasma reagin card test was 100%; between TRUST and the Venereal Disease Research Laboratory slide test it was 75.0%; and between the rapid plasma reagin card and Venereal Disease Research Laboratory slide tests it was 60.0%.

Seronegative dementia paralytica: report of a case.

Dementia paralytica may present diagnostic difficulties when routine serological test using a non-treponemal antigen is non-reactive. We present an illustrative demented patient who initially had negative VDRL test both in his serum and cerebrospinal fluid. However, the brain biopsy specimen showed active meningoencephalitis. By special staining technique, a spiral organism was found in the brain exhibiting morphology perfectly compatible with treponema pallidum. Later in the course, the VDRL became reactive in the blood but remained non-reactive in the cerebrospinal fluid. On the basis of the experience of other workers in the field and ours with this patient, we advise the use of FTA-ABS test as a screening procedure in patients with neurological problems of possible syphilitic origin. We urge further research in this field.

Experience with VDRL Flocculation Antigen in the Kolmer Complement Fixation Test

IN RECENT years interest has been concentrated on treponemal antigens and little attention has apparently been given to improvement of the currently available nontreponemal antigens. This is unfortunate, since an easily available lipoidal antigen with improved specificity would be of extreme value in the laboratory. In the United States, with its premarital and prenatal laws, millions of serologic tests for syphilis are performed on presumably healthy individuals. All too frequently, particularly with cardiolipin antigens commercially available, reactive laboratory findings are obtained which are not supported by clinical findings. Various estimates of biologic false positive reactions with routine procedures have been advanced by various authors. Variation in these figures is wide. They, of course, are influenced by the type of population group evaluated, the serologic procedures and type of antigen employed, and the definition of positivity used. Deservedly or not, the current criterion of the value of a serologic test for syphilis is its sensitivity and specificity in comparison with the sensitivity and specificity of the Tbreponema palliduim immobilization (TPI) test of Nelson and Mayer. Using the TPI test as a reference, rather high false positive figures have been found with standard lipoidal antigens. MacPherson, Ledbetter, and Martens (1) reported results of 21 to 40 percent of routine reactive tests as biologic false positives, and a number of other authors, including Moore and Lutz (2), reported 40 percent false positives, In a comparative study of 572 serums which were reactive with nontreponemal tests, Wilkinson (3) found that the Kahn test gave 17 percent nonspecific reactions, the Wassermann test with lipoidal antigen 13 percent, and the Wassermann test with cardiolipin antigen 23 percent. In 244 patients found to be seropositive on routine testing during pregnancy, blood tests of 27.5 percent gave presumed nonspecific reactions. In our own laboratory, of 796 reactive VDRL slide tests, 435, or 54.6 percent, were assumed to be biologic false positives, with the TPI test used as the reference test. Of 724 reactive cardiolipin Kolmer tests, 385, or 53.2 percent, were in the same category. These figures were obtained on specimens submitted to us for TPI tests, and these cases can consequently be placed in the problem category.

Comparison of the fluorescent treponemal antibody test with other tests for syphilis on cerebrospinal fluids.

Tests for syphilis on cerebrospinal fluids were evaluated in the Washington, D.C., Serology Conference of 1941 (J. vener. Dis. Inform., 1942), but spinal fluids were omitted from the later Serology Evaluation and Research Assembly Study in 1956-57 (S.E.R.A., 1959). Since this earlier evaluation, several treponemal antigen tests have been described. The Treponema pallidum immobilization (TPI), fluorescent treponemal antibody (FTA), and Kolmer complement-fixation tests using Reiter protein antigen (KRP) are three tests designed to detect antibodies differing from those that caused reactivity in the non-treponemal antigen tests. The FTA test has been used for testing sera, but has not properly been evaluated as a spinal fluid test. This study was conducted to evaluate the FTA test in comparison with other treponemal tests for syphilis on spinal fluids. The VDRL spinal fluid test was included in this study to offer a comparison of the non-treponemal with the treponemal test results.