Presidential Address to the M.S.S.V.D. Systemic disease and the biological false positive reaction

Recent trends in the serologic diagnosis of syphilis

Complexities in the diagnosis of syphilis continue to challenge clinicians. While direct tests (e.g., microscopy or PCR) are helpful in early syphilis, the mainstay of diagnosis remains serologic tests. The traditional algorithm using a nontreponemal test (NTT) followed by a treponemal test (TT) remains the standard in many parts of the world. More recently, the ability to automate the TT has led to the increasingly widespread use of reverse algorithms using treponemal enzyme immunoassays (EIAs). Rapid, point-of-care TTs are in widespread use in developing countries because of low cost, ease of use, and reasonable performance. However, none of the current diagnostic algorithms are able to distinguish current from previously treated infections. In addition, the reversal of traditional syphilis algorithms has led to uncertainty in the clinical management of patients. The interpretation of syphilis tests is further complicated by the lack of a reliable gold standard for syphilis diagnostics, and the newer tests can result in false-positive reactions similar to those seen with older tests. Little progress has been made in the area of serologic diagnostics for congenital syphilis, which requires assessment of maternal treatment and serologic response as well as clinical and laboratory investigation of the neonate for appropriate management. The diagnosis of neurosyphilis continues to require the collection of cerebrospinal fluid for a combination of NTT and TT, and, while newer treponemal EIAs look promising, more studies are needed to confirm their utility. This article reviews current tests and discusses current controversies in syphilis diagnosis, with a focus on serologic tests.

Canadian Public Health Laboratory Network laboratory guidelines for the use of serological tests (excluding point-of-care tests) for the diagnosis of syphilis in Canada

Syphilis, caused by the bacterium Treponema pallidum subsp. pallidum, is an infection recognized since antiquity. It was first reported at the end of the 15th century in Europe. Infections may be sexually transmitted as well as spread from an infected mother to her fetus or through blood transfusions. The laboratory diagnosis of syphilis infection is complex. Because this organism cannot be cultured, serology is used as the principal diagnostic method. Some of the issues related to serological diagnoses are that antibodies take time to appear after infection, and serology screening tests require several secondary confirmatory tests that can produce complex results needing interpretation by experts in the field. Traditionally, syphilis screening was performed using either rapid plasma reagin or Venereal Disease Research Laboratory tests, and confirmed by treponemal tests such as MHA-TP, TPPA or FTA-Abs. Currently, that trend is reversed, ie, most of the laboratories in Canada now screen for syphilis using treponemal enzyme immunoassays and confirm the status of infection using rapid plasma reagin or Venereal Disease Research Laboratory tests; this approach is often referred to as the reverse algorithm. This chapter reviews guidelines for specimen types and sample collection, treponemal and non-treponemal tests utilized in Canada, the current status of serological tests for syphilis in Canada, the complexity of serological diagnosis of syphilis infection and serological testing algorithms. Both traditional and reverse sequence algorithms are recommended and the algorithm used should be based on a combination of local disease epidemiology, test volumes, performance of the proposed assays and available resources.

Comparative study of Treponemal and non-Treponemal test for screening of blood donated at a blood center

The non-Treponemal tests such as Rapid Plasma Reagin test (RPR) or the Venereal Disease Reference Laboratory test are the most commonly used test for screening of syphilis in the blood centers in India. Now, with the availability of Enzyme-linked immunosorbent assay (ELISA) and Immunochromatographic assays in the market, we decided to evaluate these assays in comparison with Treponema pallidum Haemagglutination Assay (TPHA) which was considered as a gold standard for this study. A total of 8 685 samples of voluntary blood donors were tested on Trepolisa 3.0 and then the initially reactive samples were retested in duplicate on the same assay as well as on Omega Pathozyme, RPR, RAPHA (Rapid Anti-Treponema pallidum Assay), and TPHA. Of the 158 initially reactive samples, 104 were repeatedly reactive on the same assay, 85 were reactive with RPR, 77 were reactive with RAPHA, 60 were reactive on Omega, and 53 were confirmed reactive on TPHA. 48 (56.4%) of the results on RPR were biological false positive, while 21.9% of results were false negative on RPR. We evaluated that Omega Pathozyme was quite in agreement with TPHA as compared with Trepolisa 3.0, RAPHA, and RPR. We concluded that Omega Pathozyme (ELISA) can be considered as a suitable test for screening of syphilis in a blood center.

Evaluation of the usefulness of Treponema pallidum hemagglutination test in the diagnosis of syphilis in weak reactive Venereal Disease Research Laboratory sera

BACKGROUND AND OBJECTIVES

Biological false positive (BFP) reactivity by the Venereal Disease Research Laboratory (VDRL) test used for diagnosis of syphilis is a cause for concern. The use of the VDRL as a screening procedure is challenged by some studies. The aim of this study is to determine the prevalence of BFP reactions in different subject groups and to assess the usefulness of Treponema pallidum hemagglutination (TPHA) test in low titre VDRL reactive sera.

MATERIALS AND METHODS

A total of 5785 sera from sexually transmitted diseases (STD) clinic attendees, antenatal clinic attendees, husbands of antenatal cases, peripheral health centres attendees (representing community population) and from patients referred from different OPDs/wards were screened for BFP reactions by the VDRL test. Sera reactive in the VDRL test were confirmed by the TPHA test.

RESULTS

Out of 80 qualitative VDRL reactive sera, 68 had <1:8 titre on quantitation and TPHA was positive in 59 samples, indicating BFP reactivity in 0.2% in all the subject groups. BFP was nil in the community population. The male-to-female ratio of BFP reactions was 2:1. VDRL and TPHA positivity was highest (76%) in the age group of 20-29 years. The seroprevalence of syphilis varied from 0.4% to 3.5% in different patient groups.

CONCLUSIONS

The results of this study highlight that the TPHA positivity was high (86.8%) in sera with VDRL titre less than 1:8. Therefore, for the diagnosis of syphilis, it is recommended that a confirmatory test such as TPHA should be performed on all sera with a reactive VDRL regardless of its titre.

Evaluation of the usefulness of Treponema pallidum hemagglutination test in the diagnosis of syphilis in weak reactive Venereal Disease Research Laboratory sera

Background and Objectives:

Biological false positive (BFP) reactivity by the Venereal Disease Research Laboratory (VDRL) test used for diagnosis of syphilis is a cause for concern. The use of the VDRL as a screening procedure is challenged by some studies. The aim of this study is to determine the prevalence of BFP reactions in different subject groups and to assess the usefulness of Treponema pallidum hemagglutination (TPHA) test in low titre VDRL reactive sera.

Materials and Methods:

A total of 5785 sera from sexually transmitted diseases (STD) clinic attendees, antenatal clinic attendees, husbands of antenatal cases, peripheral health centres attendees (representing community population) and from patients referred from different OPDs/wards were screened for BFP reactions by the VDRL test. Sera reactive in the VDRL test were confirmed by the TPHA test.

Results:

Out of 80 qualitative VDRL reactive sera, 68 had <1:8 titre on quantitation and TPHA was positive in 59 samples, indicating BFP reactivity in 0.2% in all the subject groups. BFP was nil in the community population. The male-to-female ratio of BFP reactions was 2:1. VDRL and TPHA positivity was highest (76%) in the age group of 20-29 years. The seroprevalence of syphilis varied from 0.4% to 3.5% in different patient groups.

Conclusions:

The results of this study highlight that the TPHA positivity was high (86.8%) in sera with VDRL titre less than 1:8. Therefore, for the diagnosis of syphilis, it is recommended that a confirmatory test such as TPHA should be performed on all sera with a reactive VDRL regardless of its titre.

Molecular characterization of syphilis in patients in Canada: azithromycin resistance and detection of Treponema pallidum DNA in whole-blood samples versus ulcerative swabs

Although detection of Treponema pallidum DNA in whole-blood specimens of syphilis patients has been reported, it is uncertain at what stage of the disease such specimens are most suitable for the molecular diagnosis of syphilis. Also, few studies have directly compared the different gene targets for routine laboratory diagnostic usage in PCR assays. We examined 87 specimens from 68 patients attending two urban sexually transmitted disease clinics in Alberta, Canada. PCR was used to amplify the T. pallidum tpp47, bmp, and polA genes as well as a specific region of the 23S rRNA gene linked to macrolide antibiotic susceptibility. In primary syphilis cases, PCR was positive exclusively (75% sensitivity rate) in ulcerative swabs but not in blood specimens, while in secondary syphilis cases, 50% of the blood specimens were positive by PCR. Four out of 14 (28.6%) of our PCR-positive syphilis cases were found to be caused by an azithromycin-resistant strain(s). Our results confirmed that swabs from primary ulcers are the specimens of choice for laboratory diagnostic purposes. However, further research is required to determine what specimen(s) would be most appropriate for molecular investigation of syphilis in secondary and latent syphilis.

Lower genital tract infections in infertile Nigerian women compared with controls

OBJECTIVE

To investigate the possibility that infertile Nigerian women have a higher rate of cervical colonisation with pathogenic and facultative organisms than fertile controls.

DESIGN

The prevalence of common microorganisms in the vagina and endocervical canals of infertile women was compared with that of pregnant controls.

SETTING

The Obafemi Awolowo University Hospital Maternity Centre.

SUBJECTS

92 infertile women were compared with 86 pregnant controls.

MAIN OUTCOME MEASURES

rates of isolation of Neisseria gonorrhoeae, Candida albicans, Trichomonas vaginalis and other facultative organisms in cases and controls.

RESULTS

The rate of isolation of Neisseria gonorrheae was 17.4% among infertile women compared with 10.5% in the group of pregnant women (p > 0.05). There was no significant difference between the groups in the rate of isolation of Candida albicans, Trichomonas vaginalis and other facultative organisms. High rates of isolation of microorganisms were observed in both groups. However, women with secondary infertility had higher rate of carriage of Neisseria gonorrheae, Candida albicans and Staphylococcus aureus as compared with women with primary infertility. Nearly 15% of infertile women had previous episodes of pelvic inflammatory disease and 26% had had induced abortions. A positive history of vaginal discharge was a poor predictor of vagina and endocervical carriage of microorganisms.

CONCLUSIONS

High rates of pathogenic organisms exist in the lower genital tract of infertile women and controls. Women with secondary infertility are more likely to have pathogenic organisms than women with primary infertility. A policy of routinely screening women for lower genital tract infections should be pursued in this population because of the high rate of infection.

Evaluation of a Treponema pallidum enzyme immunoassay as a screening test for syphilis

The CAPTIA Syphilis-G enzyme immunoassay for the detection of antibodies to Treponema pallidum was evaluated as a screening test for syphilis in comparison with the standard rapid plasma reagin (RPR) test. One thousand samples were tested, and the standard fluorescent treponemal antibody absorption test and the standard microhemmaglutination test were used to confirm the presence of treponemal antibodies. Diagnosis of syphilis was based on traditional standard serology results. Clinical data used in the diagnosis of patients whose samples yielded conflicting results were provided by physicians. Initially, 7 patients whose samples were reactive in the RPR test and 14 patients whose samples yielded positive or equivocal results in the CAPTIA Syphilis-G test were diagnosed as not being infected. After discrepancies due to technical problems were reconciled, samples from six patients remained reactive in the RPR test and that from one patient remained positive in the CAPTIA Syphilis-G test. In addition, seven patients whose samples were nonreactive in the RPR test and two patients whose samples were negative in the CAPTIA Syphilis-G test were diagnosed as having untreated syphilis. After discrepancies were reconciled, samples from five patients remained nonreactive in the RPR test and none remained negative in the CAPTIA Syphilis-G test. Final results indicate that the specificities are 99.4 and 99.9%, respectively. In addition to the improved sensitivity and specificity of the CAPTIA Syphilis-G screen, other potential benefits of this assay lead us to believe that this method could serve as a better screening tool than the RPR test.

Biological false positive serological tests for syphilis in the Jamaican population

A total of 19,067 sera were screened for biological false positive (BFP) reactivity by the Venereal Disease Research Laboratory (VDRL) test. Sera which were reactive in the VDRL test were confirmed by the fluorescent treponemal antibody absorption (FTA-ABS) test. BFP reactions were detected in 0.59% of the general population, 0.72% of pregnant women and 11.8% of patients with systemic lupus erythematosus (SLE). The rate of BFP reactors among pregnant women did not differ significantly from the general population. The female to male ratio of BFP in the general population was 2:1 whilst that in the group of patients with SLE was 8:1. The overall seroprevalence of syphilis was 2.2%.

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This article summarizes the diagnostic possibilities when the physician is faced with a serological test which is positive for syphilis. Management, sensitivity and specificity of tests, and differential diagnosis are illustrated by tables.

Modern neurosyphilis: a partially treated chronic meningitis

Approximately 5,000 new cases of neurosyphilis may occur in the United States each year. General paresis and tabes dorsalis, however, have become relatively rare since the introduction of penicillin. Seizures, neuro-ophthalmologic symptoms, stroke and acute meningoencephalitis are currently the most common manifestations of neurosyphilis. In more than a third of patients with neurosyphilis, nontreponemal tests for syphilis (such as VDRL) are negative and should not be used to exclude the diagnosis. Specific treponemal tests are more sensitive and more specific. Examination of the cerebrospinal fluid may show no abnormalities in neurosyphilis and is not an infallible guide to the activity of the infection. Penicillin is the only proven antibiotic treatment of neurosyphilis. However, low-dose regimens do not produce spirocheticidal concentrations in the brain, and high-dose penicillin therapy is recommended to insure eradication of the spirochetes. Doxycycline, a tetracycline derivation that achieves relatively high concentration in the brain, may also be effective.

Non-specific positive test results to syphilis in dermatological diseases

Sera from 3028 patients attending a dermatological clinic were examined by the fluorescent treponemal antibody (FTA) test, the fluorescent antibody-absorbed (FTA-ABS) test, the Venereal Disease Research Laboratory (VDRL) test, and Kolmer's test. Eleven cases of late syphilis were found. Sera from 63 (2.08%) of the remaining 3017 patients showed non-specific results; these were found more frequently in patients with pyodermas, neoplasms, acne, mycoses, crural ulceration, and psoriasis than in those with other diseases. No non-specific results were observed in patients with bullous skin diseases and only a few in patients with viral skin diseases and chronic lupus erythematosus. The test producing the most non-specific results was the FTA test, followed by the FTA-ABS test, the VDRL test, and Kolmer's test.

Clinical application of serological tests for syphilis

This article differentiates and describes the serological tests for syphilis- antitreponemal antibody tests (TPI, FTA-ABS, TPHA), non-treponemal antigen test (VDRL)-their clinical and serological correlation, the responses to therapy and the biologically false positive syndrome.

Influence of genital herpes on results of fluorescent treponemal antibody absorption test

Both the fluorescent treponemal antibody absorption (FTS-ABS) test and Venereal Disease Laboratory (VDRL) test for syphilis were performed routinely on 113 men with histories of genital ulcerations. The difference in negative VDRL and borderline FTS-ABS results between patients with and without herpes simplex virus in their genital ulcers and no evidence of previous or untreated syphilis was not statistically significant. Furthermore, use of the FTA-ABS test as a confirmatory rather than a screening test eliminates false-positive, borderline, or reactive results in patients with non-syphilitic ulcers.

Polymyositis with biological false-positive serological test for syphilis. A case report

A young female came to the clinic with polymyositis and a biological false-positive serological test for syphilis (BFP reaction). Polymyositis, like other connective-tissue diseases, should be considered in the study of BFP reactors.

Leucocyte migration inhibition with mitochondria in human autoimmune thyroid disorders

Leucocyte migration inhibition tests (LMT) with rat and human liver mitochondria are reported in forty-nine thyroid patients and forty-seven healthy controls. Whereas normal subjects and colloid goitre cases were inactive in this test, patients with autoimmune thyroiditis and thyrotoxicosis gave positive mitochondrial reactions which paralleled the organ-specific thyroid microsomal LMT obtained in the same patients and were not species dependent. The active antigen may be in the inner membranes of the particles.

As with thyroid microsomes, intense inhibition with mitochondria was seen in the hypercellular variant of Hashimoto goitre characterized serologically by low or absent thyroglobulin antibodies, and the lowest LMT values occurred in the rare cases showing poor response to thyroxine therapy. An inverse correlation was found between mitochondrial LMT and thyroglobulin antibody titres. Surprisingly, weak LMT was also found in four thyroid patients who happened to have mitochondrial antibodies in the serum in addition to the usual thyroidspecific reactivities. The mitochondrial LMT appears to be of widespread occurrence in autoimmune diseases and also develops following tissue injury. Its possible significance in relation to cellular immunity, cell destruction and the inflammatory response is discussed.