Fluorescent Treponemal Antibody Tests—A Summary and Comparison

A comparison of current serologic tests for syphilis shows that treponemal tests are preferable to reagin tests in detecting specific antibodies, but that reagin tests are best for determining the response to treatment. The newly developed fta-absorption technique is suggested as a reliable, inexpensive test for treponemal antibodies.     

Laboratory methods of diagnosis of syphilis for the beginning of the third millennium

Despite that the whole genome of T. pallidum, the causative agent of syphilis, has been sequenced, syphilis is, and will remain for some time, diagnosed by direct clinical observation and by laboratory methods. This review presents comprehensively most of the practical techniques used for direct detection of T. pallidum and lists all practical methods for phospholipid and treponemal antibodies detection. It describes most novel tests for syphilis, discusses problems with sero-creossreactivity in Lyme disease, immune responses in HIV-syphilis coinfected patients, and reviews serologic responses to antibiotic treatment.     

Routine Serologic Testing for Syphilis in a Community Medical Practice

A retrospective review of 8,100 serologic tests for syphilis ordered during a 42-month period yielded positive rapid plasma reagin test results in 127 patients (1.6 percent) and a positive fluorescent treponemal antibody absorption reaction in 91 patients (1.1 percent). Of the 36 cases of biologic false-positive reactions, most were in prenatal patients. Forty-six cases of syphilis were previously undiagnosed but antibiotic therapy was given in only 26 of the patients. Some 24 percent of syphilitic patients were not treated because the positive serologic findings were overlooked. Cerebrospinal fluid determinations were analyzed and cost-effectiveness of finding a single case of previously undiagnosed syphilis was calculated. We found that routine serologic tests and cerebrospinal fluid studies for syphilis in asymptomatic patients had low rates of positivity in our community hospital and outpatient practice.     

SYPHILIS AND SEROLOGIC EVALUATION OF PATIENTS—A Recurring Problem

Although syphilis is again becoming more prevalent, routine serologic testing for the disease is diminishing. A test such as the VDRL or similar test is useful for general screening. If the test is nonreactive, the probability of the patient having syphilis is minimal. If the screening test is positive, a positive reaction to a Reiter or TPI test indicates a high probability of syphilis. But a negative reaction to these tests is not full assurance of absence of disease.     

Apple Down 152: A putative case of syphilis from sixth century AD Anglo‐Saxon England

This report describes a putative case of a treponemal infection observed on a skeleton of a young male adult from the Apple Down Anglo‐Saxon cemetery dating to the sixth century AD, accompanied by grave goods indicative of a high status burial. The skeleton is well preserved and almost complete. The pathological evidence includes an extensive area of lytic destruction to the frontal bone of the skull, widespread profuse bilateral symmetrical periosteal reaction affecting scapulae, clavicles, arms, legs, hands, feet and ribs. There is also evidence of gummatous destruction on some of the long bones. Application of a differential diagnosis of all probable diseases exhibiting the individual symptoms leads to a clear conclusion that the person was infected with a treponemal pathogen. The skeleton shows none of the stigmata associated with the congenital form of treponemal disease. We propose that the evidence suggests a possible case of venereal syphilis rather than one of the endemic forms of treponemal disease. This diagnosis is based on the geographical pathogen range, the apparent low prevalence of the disease, significant social upheaval at the time, the high social status and early age of death of the individual. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.     

Tests for Syphilis—The Increasing Incidence of Biologic False Positive Reactions As Measured by Treponema Pallidum Immobilization

Analysis of data obtained in 25,787 Treponema pallidum immobilization tests in a ten-year period showed an increase in the incidence of biologic false positive (BFP) reactions for syphilis, and a decrease in the incidence of reactive TPI tests. The percentage of BFP tests increased from 54.2 per cent in 1953 to 70.7 per cent in 1962.Reaction to a standard serologic test for syphilis (STS) indicates only that the patient may have syphilis. A subsequent non-reactive TPI test remains the best procedure for ruling out a diagnosis of syphilis. Thus the clinician should be made more aware of the fact that a biologic false positive reaction strongly implies the existence of another disease, the cause of which should be investigated.     

Current Status of the Treatment of Syphilis

Penicillin remains the treatment of choice for syphilis, with sustained low blood levels curing virtually all patients having early syphilis and halting disease progression in most patients with symptomatic syphilis. Tetracycline, erythromycin or cephalothin yields similar cure rates for patients with early syphilis who are allergic to penicillin. The efficacy of non-penicillin regimens for the treatment of late syphilis is uncertain. Results of Venereal Disease Research Laboratory (VDRL) or other reagin tests should become negative or remain at very low titer following adequate therapy, although results of Treponema pallidum immobilization (TPI) and fluorescent treponemal antibody-absorbed (FTA-ABS) tests often remain positive.     

Treponemal serologic tests; experiences of the Bacteriology Laboratory,California State Department of Public Health

In a study of the relationship of clinical impression regarding syphilis and age, sex and pregnancy status to treponemal serologic test reactivity, it was noted that in diagnostic "problem cases" the standard lipid serologic test titers did not differentiate between syphilitic and biologic false positive reactors. Preliminary data indicated that heroin addiction may be a source of biologic false reactions and that pregnant women with standard serologic test reactivity have a lower treponemal reactivity rate than other women with lipid serologic reactivity.     

A Cost-Benefit Analysis of California's Mandatory Premarital Screening Program for Syphilis

As do most states, California requires premarital serologic tests for syphilis. The Venereal Disease Research Laboratory (VDRL) test and a fluorescent treponemal antibody-absorbed (FTA-ABS) are often used in series for this purpose. In 1979 in California, there were approximately 300,000 persons tested premaritally, but only 35 were found to have asymptomatic infectious syphilis (incidence=0.012%). Including all the direct costs of this screening program, the yearly costs of premarital screening is $8.5 million or almost $240,000 per case found. If one takes into account the sensitivities and specificities of the tests, one still has 6 false-negative and 90 false-positive tests using the 1979 figures. The benefits of the program are the number of cases of congenital syphilis that are prevented. Using a worse-case method, no more than 1.5% of the cases of syphilis detected would result in a case of congenital syphilis. The estimated benefits would result in a savings of approximately $161,000. The economic costs of the premarital screening program far outweigh the benefits.     

TREPONEMAL SEROLOGIC TESTS—Experiences of the Bacteriology Laboratory,California State Department of Public Health

In a study of the relationship of clinical impression regarding syphilis and age, sex and pregnancy status to treponemal serologic test reactivity, it was noted that in diagnostic “problem cases” the standard lipid serologic test titers did not differentiate between syphilitic and biologic false positive reactors. Preliminary data indicated that heroin addiction may be a source of biologic false reactions and that pregnant women with standard serologic test reactivity have a lower treponemal reactivity rate than other women with lipid serologic reactivity.     

Automated Fluorescent Treponemal Antibody Test: Instrument and Evaluation

Two evaluations of the automated fluorescent treponemal antibody (AFTA) test for the serodiagnosis of syphilis are described. The results of AFTA and manually performed fluorescent treponemal antibody-absorption (FTA-ABS) tests were compared on serum samples from clinically defined donor groups, and the reproducibility of each procedure was studied. Significant improvement of AFTA test results was obtained in the most recent study after developmental modifications of the instrument and test technique. AFTA test agreement with both syphilis and nonsyphilis categories was considered good. With the increasing usage of the FTA-ABS test as an effective tool for the diagnosis of syphilis, successful automation of this procedure is particularly timely and significant.     

Evaluation of the Qualitative and Automated Quantitative Microhemagglutination Assay for Antibodies to Treponema pallidum

Qualitative and quantitative microhemagglutination assays for antibodies to Treponema pallidum (MHA-TP) were performed on 314 syphilitic and 597 presumably nonsyphilitic sera, and the results were compared with those of the fluorescent treponemal antibody-absorbed (FTA-ABS), the Treponema pallidum immobilization (TPI), and the Veneral Disease Research Laboratory (VDRL) tests. MHA-TP sensitivity was similar to that of the other tests in all stages of syphilis except primary syphilis, in which MHA-TP reactivity was only 64% compared with 82% in the FTA-ABS test, 73% in the VDRL test, and 67% in the TPI test. MHA-TP specificity was satisfactory and comparable to that of the other treponemal tests. Quantitation of the MHA-TP test was automated by use of Autotiter II equipment. Titers tended to become elevated later in the course of syphilis and to remain elevated longer than did VDRL titers. Reproducibility of the quantitative MHA-TP test was satisfactory, with duplicate tests agreeing within one doubling dilution on 97.5% of 351 reactive sera. Poor reproducibility was obtained with sera giving minimal reactions in the qualitative test, and such sera should be routinely retested. The MHA-TP is less time-consuming and costly than the FTA-ABS test and could be used in conjunction with the VDRL or another reagin test for syphilis to eliminate a large number of the FTA-ABS tests now required.     

Serological diagnosis of syphilis: comparison of the Trep-Chek IgG enzyme immunoassay with other screening and confirmatory tests

The Trep-Chek IgG Enzyme Immunoassay (Trep-Chek IgG EIA) was evaluated with 604 serum specimens submitted for syphilis serology from patients across Canada against a battery of conventional syphilis serology tests, including the Rapid Plasma Reagin (RPR) test, the Venereal Disease Research Laboratory (VDRL) test, the Treponema pallidum passive particle agglutination (TP-PA) test, the fluorescent treponemal antibody absorption (FTA-ABS) test, and the newer confirmatory test, Innogenetics INNO-LIA. On the basis of a consensus result derived from these serologic tests, 34 specimens were found to be syphilis-positive (28 active and six past infections), and 570 were syphilis-negative (including 12 biological false positives). When the test results on this set of samples were compared to those obtained with the conventional tests RPR, VDRL, TP-PA, and FTA-ABS, the sensitivity and specificity of the Trep-Chek IgG EIA were found to be 85.3% and 95.6%, respectively. Without further evaluation, we do not recommend use of the Trep-Chek IgG EIA as a stand-alone test for either screening or confirmatory syphilis serology.     

CONGENITAL SYPHILIS IN CALIFORNIA

Routine serologic tests for syphilis (as required by California law governing prenatal examination) and penicillin therapy during pregnancy for infected mothers have been major factors in the prevention of congenital syphilis in California during the past ten years. In 1940 one of each 822 infants had the disease, as indicated by morbidity reports of congenital syphilis in infants under the age of one year. In 1950 the ratio was one in 8,148. To determine why congenital syphilis continues to occur, a study of the 134 cases reported over a two-year period was made with the cooperation of local health officers and practicing physicians. It showed that in 76 per cent of cases the mother did not consult a physician prior to delivery or reported so late in pregnancy that the infant was born before adequate penicillin therapy could be given. In another 15 per cent syphilis developed in the mother during pregnancy after a negative reaction to a prenatal serologic test. The other 9 per cent of cases were due to various factors, such as infectious relapse or reinfection in previously adequately treated mothers. The study indicated that most cases occur in the lower socioeconomic population groups. Seventy-four per cent of cases were in infants delivered in county hospitals.     

Regional, social, and evolutionary perspectives on treponemal infection in the Southeastern United States

The origin and geographic distribution of syphilis, a form of treponemal infection, have long been regarded as among the most important medical riddles of prehistoric and historic disease evolution. In this study, we expand on previous discussions of the origin, evolution, and relationship of treponemal infections as they occur in the prehistoric southeastern United States. Individuals from 25 skeletal series (n = 2,410 individuals) were examined for cranial and dental lesions characteristic of treponemal infection. They lived between the Archaic period (8000-1000 BC) and protohistoric period (AD 1500-1600), and in physiographic zones from the coast to the mountains of Alabama, Florida, North Carolina, and Tennessee. Radial cranial scars were found for 47 individuals, but none of the four cases of dental lesions could be attributed to congenital syphilis. Differences in frequency of cranial lesions by region were minimal, with the least number of cases found for the mountains, but the frequency of positive cases tended to increase through time. It is suggested that increasing population density and changing behaviors, rather than novel strains of the treponemal pathogen, are responsible for the chronological increase in the frequency of positive cases.     

Quantitative profile of cardiolipin and group treponemal IgD antibodies in syphilis estimated by single radial immunodiffusion technique (SRID)

150 serum samples (reactive in VDRL, Reiter-ELISA, FTA-Abs tests), from male patients 25-45 years old, in various stages of syphilis whether treated or untreated, were tested for IgD by SRID. On 154 sera from healthy males 25-45 years old, the reference normal values for IgD levels were established, as: 0-131.2 IU/ml with a mean of 29.92 +/- 29.61 IU/ml. Cardiolipin and group treponemal fraction values for IgD class were obtained by assessing the difference between the immunodiffusion diameter values produced by sera before and after complete absorption with VDRL antigen or delipidated T. reiteri suspension. The individual, mean +/- SD values (expressed in IU/ml) and the percentage of cardiolipin and treponemal IgD of the total IgD class were calculated for each stage. The mean value of the total IgD class, excepting secondary syphilis (sigma 2) 52.53 +/- 26.66 IU/ml), did not overstep the normal levels but all minimal individual values from syphilitic patients (7.09-14.89 IU/ml) surpassed significantly the normal minimal values which were less than or equal to 3.54 IU/ml. The total lack of cardiolipin (IgD and the presence of group treponemal IgD in all sera of the syphilis stages studied were manifest. The group treponemal IgD mean values ranged between 7-9 IU/ml, with a maximum of 19.32 +/- 10.58 IU/ml in sigma 2 followed by latent syphilis (sigma lat) with a mean value of 9.37 +/- 4.9 IU/ml. A significant percentage of treponemal IgD vs total IgD was recorded: primary syphilis (sigma 1) 32.01%, primary-secondary syphilis (sigma 1-2) 28.76%, sigma 2 36.77%, sigma lat and treated persistent seroreactive syphilis (sigma t+) 29.61%. The high proportion of treponemal IgD in latent and treated persistent reactive syphilis suggests a steady activation of B lymphocytes by treponemal antigens and presumably is an expression of an active infectious process. The absence of cardiolipin IgD and the presence of only the treponemal IgD, in all sera from all stages, might confer to their detection an extremely specific diagnostic value in syphilis.     

Europium Nanoparticle-Based High Performing Immunoassay for the Screening of Treponemal Antibodies

Treponema pallidum subspecies pallidum (Tp) is the causative agent of syphilis which mainly spreads through sexual contact, blood transfusion and perinatal route. In order to curtail the spread of the infection and to clinically manage the disease, timely, accurate and reliable diagnosis is very important. We have developed an immunoassay for the detection of treponemal antibodies in human serum or plasma samples. In vivo biotinylated and non-biotinylated versions of the recombinant antigen were designed by the fusion of three Tp-specific antigens namely Tp15, Tp17 and Tp47. These fusion antigens were expressed in E. coli and purified using single-step metal affinity chromatography. Biotinylated fusion antigen immobilized on streptavidin coated plate was used to capture the treponemal antibodies and the non-biotinylated antigen coated on europium nanoparticles was used as tracer. Assays with two different incubation times of 10 min and 1 h were developed, and following the incubation the europium fluorescence was measured using time-resolved fluorometry. The developed time-resolved fluorometric (TRF) immunoassays were evaluated with in-house and commercial serum/plasma sample panels. For well-established treponemal antibodies positive or negative samples, the sensitivity of TRF immunoassay with 10 min incubation time was 97.4%, and of TRF immunoassay with 1 h incubation time was 98.7%, and the specificities of both the TRF immunoassays were 99.2%. For the samples with discordant results with the reference assays, both the TRF immunoassays showed better specificity than the Enzygnost syphilis enzyme immunoassay as a screening test. The two different incubation times did not have any significant effect on the signal to cutoff (S/Co) ratios obtained with the two immunoassays (p = 0.06). Our results indicate that the developed immunoassay with a short incubation time of 10 min has the potential to be used in clinical laboratories and in blood-bank settings as a screening test for treponemal antibodies.     

Characterization of the antigenic determinants and host components in immune complexes from patients with secondary syphilis

Sera from patients with secondary syphilis were evaluated for abnormal levels of circulating immune complexes (IC), immunoglobulins (Ig), and complement components. Clq-solid-phase assays (Clq-SPA) that made use of monoclonal and polyclonal antibodies directed against IgG subclasses indicated that human IC were composed primarily of IgG3 and IgG1; these findings appeared consistent with subclass profile responses of electrophoretically transferred blots (Western blots) of Treponema pallidum reacted with syphilitic sera. Complexes were isolated from reactive sera by polyethylene glycol precipitation followed by either anti-Clq column chromatography or protein A-Sepharose chromatography. Although qualitative and quantitative differences were noted, all purified materials contained a treponemal polypeptide antigen with a m.w. of approximately 87,000. Subsequent analysis of this polypeptide, which was also present in purified IC from rabbits with experimental syphilis, suggests that it may represent the fibronectin receptor of the organism. The 76,000 and 66,000 materials, earlier identified in purified rabbit IC, appeared to represent C-terminal degradation products of fibronectin presumably of host origin, rather than treponemal antigens. Although fibronectin binds avidly to Clq and could represent a co-precipitable contaminant throughout the isolation procedure, anti-fibronectin antibodies in the sera of patients detectable by radioimmunoassay and the present of antibodies to 76,000 and 66,000 dalton fibronectin fragments in the globulin fractions of disassociated complexes argues against such a conclusion.     

Two probable cases of treponemal disease of Medieval date from England

Two British Medieval skeletons are described. Paleopathological examination suggests that treponemal disease was present in each case. Radiocarbon dating indicates that one is firmly pre-Columbian, and the other of likely pre-Columbian date. The implications for our understanding of the history and geographic spread of the treponemal diseases, particularly venereal syphilis, are discussed.     

Treponema paraluis-cuniculi infection in a commercial rabbitry: epidemiology and serodiagnosis

The epidemiology of Treponema paraluis-cuniculi infection in a commercial rabbit breeding facility was described using several serologic tests. The Venereal Disease Research Laboratory, rapid plasma reagin, microhemagglutination and fluorescent treponemal antibody-absorption tests were used to detect antibodies to T paraluis-cuniculi. Young adult New Zealand white rabbits, tested prior to entry into the breeding program, were nearly always free of T paraluis-cuniculi infection. In adult females, the prevalence of T paraluis-cuniculi infection increased with parity; females para 6 or greater were usually seropositive. Most adult males seroconverted within 6 months of entering the breeding program; all males were seropositive after 12 months in the breeding program. This suggested that T paraluis-cuniculi spreads mainly by horizontal transmission during breeding in adult rabbits. Of the two nontreponemal antigen tests used, the Venereal Disease Research Laboratory test was more sensitive, whereas the rapid plasma reagin test was more specific in detecting T paraluis-cuniculi infection; the fluorescent treponemal antibody-absorption test was used as the confirmatory treponemal antigen test. However, neither nontreponemal antigen test was completely satisfactory. On the other hand, the sensitivity and specificity of the microhemagglutination test compared favorably with the fluorescent treponemal antibody-absorption test. Since the microhemagglutination test combines desirable features of both a screening and verification procedure, it should be the test of choice for detection of T paraluis-cuniculi infection.