Syphilis fast latex agglutination test, a rapid confirmatory test.

Using 255 serum samples with various reactivities, we evaluated the Syphilis Fast latex agglutination test (Syphilis Fast) against the Treponema pallidum particle agglutination test (TP-PA) for confirming a diagnosis of syphilis. We found 98.8% agreement between the Syphilis Fast and the TP-PA. The Syphilis Fast, however, had a couple of advantages over the TP-PA: the test takes only 8 min to perform and produces results that are easy to read. It appears to be a good confirmatory test for syphilis, especially for point-of-care clinics such as prenatal or sexually transmitted disease clinics.

Maternal and congenital syphilis in Bolivia, 1996: prevalence and risk factors.

OBJECTIVES: The present study was carried out in seven maternity hospitals to determine the prevalence of maternal syphilis at the time of delivery and the associated risk factors, to conduct a pilot project of rapid syphilis testing in hospital laboratories, to assure the quality of syphilis testing, and to determine the rate of congenital syphilis in infants born to women with syphilis at the time of delivery--all of which would provide baseline data for a national prevention programme in Bolivia. METHODS: All women delivering either live-born or stillborn infants in the seven participating hospitals in and around La Paz, El Alto, and Cochabamba between June and November 1996 were eligible for enrolment in the study. FINDINGS: A total of 61 out of 1428 mothers (4.3%) of live-born infants and 11 out of 43 mothers (26%) of stillborn infants were found to have syphilis at delivery. Multivariate analysis showed that women with live-born infants who had less than secondary-level education, who did not watch television during the week before delivery (this was used as an indicator of socioeconomic status), who had a previous history of syphilis, or who had more than one partner during the pregnancy were at increased risk of syphilis. While 76% of the study population had received prenatal care, only 17% had syphilis testing carried out during the pregnancy; 91% of serum samples that were reactive to rapid plasma reagin (RPR) tests were also reactive to fluorescent treponemal antibody-absorption (FTA-ABS) testing. There was 96% agreement between the results from local hospital laboratories and national reference laboratories in their testing of RPR reactivity of serum samples. Congenital syphilis infection was confirmed by laboratory tests in 15% of 66 infants born to women with positive RPR and FTA-ABS testing. CONCLUSION: These results indicate that a congenital syphilis prevention programme in Bolivia could substantially reduce adverse infant outcomes due to this disease.

Comparison of the Serodia Treponema pallidum particle agglutination, Captia Syphilis-G, and SpiroTek Reagin II tests with standard test techniques for diagnosis of syphilis.

We compared the microhemagglutination assay for Treponema pallidum (MHA-TP), a treponemal test, with two other treponemal tests, the Serodia Treponema pallidum particle agglutination (TP-PA) assay and the Captia Syphilis-G enzyme immunoassay, using 390 clinical serum samples. We also compared two nontreponemal tests, the rapid plasma Reagin (RPR) card test and the SpiroTek Reagin II test. Agreements of the MHA-TP with the TP-PA test and the Syphilis-G test were 97.4 and 97.7%, respectively. There was 89.2% agreement between the RPR and Reagin II tests. The Reagin II test was more apt to be reactive if the treponemal test was also reactive. We conclude that either the Serodia TP-PA test or the Captia Syphilis-G test is an appropriate substitute for the MHA-TP and that the Spirotek Reagin II test could substitute for the RPR test as a screening test.

The use of Western blotting as the confirmatory test for syphilis in patients with rheumatic disease.

OBJECTIVE: As a direct or indirect result of antiphospholipid antibody production, subjective laboratory interpretation, and false positive results, the common serologic tests for syphilis have been inherently inaccurate diagnostic tests in patients with systemic lupus erythematosus (SLE) and other autoimmune diseases. We assessed the diagnostic accuracy of syphilis testing in patients with SLE and other autoimmune diseases using the treponemal Western blot (TWB) as the gold standard. METHODS: A prospective cohort study carried out at a tertiary care medical center. We studied 107 patients with autoimmune disease, 50 with at least one positive serologic test for syphilis and 57 disease matched controls. Prior to enrollment all eligible patients underwent a clinical assessment performed by at least 2 rheumatologists to confirm a diagnosis of rheumatic disease. All subjects underwent serologic testing, in blinded fashion, for syphilis using the rapid plasma reagin test (RPR), Venereal Disease Research Laboratory test (VDRL), fluorescent treponemal antibody absorption test (FTA-ABS), and the TWB. RESULTS: Eighty-seven percent of the patients studied were female, the mean age was 46.5 years, and the most common diagnosis at the time of enrollment was SLE. Using the TWB as the gold standard diagnostic test for syphilis, the sensitivity, specificity, and positive predictive values for each syphilis test were calculated. The sensitivity and specificity for the RPR in patients with rheumatic disease was 62.5% (95% confidence interval 24.5 to 91.5%) and 91.9% (95% CI 84.2 to 96.2%), respectively. The sensitivity and specificity for the VDRL were 37.5% (95% CI 8.5 to 75.5%) and 89.9% (95% CI 81.8 to 94.8%), respectively. Confirmatory syphilis testing using the FTA-ABS showed a sensitivity of 100% (95% CI 68.6 to 100%) and a specificity of 67.7% (95% CI 57.4 to 76.5%). Eight patients tested positive for syphilis by Western blotting. For the FTA-ABS test, there was a significantly higher number of false positive results (n = 32) compared to false negative results (n = 0), p < 0.0005. CONCLUSION: The FTA-ABS is not an accurate confirmatory test for syphilis in patients with SLE and other autoimmune diseases. While a negative FTA-ABS may exclude syphilis infection in the majority of cases, a positive FTA-ABS test result cannot assuredly confirm syphilis infection in this population. Western blotting is an accurate confirmatory test for syphilis and may be necessary to unequivocally discern the immunological response of syphilis from that of an underlying autoimmune disease.

Congenital syphilis in a newborn: an immunopathologic study.

A 3-week-old girl presented to the emergency room with respiratory distress and generalized maculopapular rash. The newborn was hospitalized with a presumptive diagnosis of congenital syphilis, but she died after 2 days of therapy. Tissue from the gastrointestinal tract, brain, liver, spleen, and lung was studied by using direct fluorescent antibody and immunohistochemical analysis (IHC) for Treponema pallidum. The inflammatory infiltrate was characterized by using IHC against CD3, CD20, CD68, and smooth muscle actin. The diagnosis of congenital syphilis was confirmed by demonstrating spirochetes in tissues with IHC and direct fluorescent antibody examination. IHC showed abundant treponemes in the small intestine and liver and occasional spirochetes in the meninges. Bacteria were seen as intact spirochetes, granular staining, or large extracellular collections of antigen. A constant pathologic feature throughout the tissues was concentric macrophage (CD68-positive) infiltrate around vessels, giving an onion-skin appearance. IHC identified the macrophages as the prime immune response in congenital syphilis.

An analysis of the value of some antigen-antibody interactions used as diagnostic indicators in a treponemal Western blot (TWB) test for syphilis.

Densiometric quantitation and spreadsheet normalization were used to refine the parameters defining a treponemal Western blot (TWB) test for syphilis. Initially using 84 defined reactive and 105 defined non-reactive sera, we determined that the immune response to the 17 kDa antigen was the most critical of the following three candidate test determinants: the 47 kDa, 17 kDa and 15.5 kDa bands. In a second study using 124 cases of clinically diagnosed syphilis and 354 "normal" donors, a diluted serum sample was included as a minimal reactive control for the 17-kDa immune response. Reactivity to all three test determinants was obligatory for a test result to be interpreted as positive. Of the 124 cases of syphilis, 7 were nonreactive by TWB (sensitivity = 94%); of the 354 normal donors, 7 tested reactive (specificity = 98%). Forty (11%) normal serum samples had detectable but less than minimal reactivity to the 17 kDa band. Frequencies of immune response to a larger group of 12 antigens were tallied for the 124 clinically diagnosed cases of syphilis and an equal subset (124) of the normal group. In the normal subset, 72% and 52% of the samples had detectable reactivity to the 47 and 15.5 kDa antigens, respectively, while 10%, 5% and 3% reacted with the 17, 24 and 44.5 kDa antigens, respectively. Follow-up TWB testing of the clinically diagnosed cases revealed that previously untreated patients with primary or secondary syphilis were more likely to a show decrease in TWB reactivity than patients with latent symptoms who had been treated previously. As a diagnostic indicator of syphilis, the 17-kDa antigen was found to have the best combined attributes of sensitivity and specificity. Although, the highly specific 44.5 kDal and 24 kDal bands were often redundant as diagnostic indicators they are useful for the interpretation of borderline results. In addition, absence of the highly sensitive 47 and 15.5 kDa indicators should be useful in resolving some problem diagnoses.

Pathology of the umbilical cord in congenital syphilis: analysis of 25 specimens using histochemistry and immunofluorescent antibody to Treponema pallidum.

Identification of Treponema pallidum in the placenta is important for diagnosis of congenital syphilis; however, spirochetes are difficult to observe in chorionic villi. To determine the sensitivity of umbilical cord examination for T pallidum, and the association of spirochetes with cord pathology, placentas were prospectively obtained from 25 women with untreated syphilis. The most common finding using hematoxylin-eosin staining was a normal-appearing umbilical cord (48%); necrotizing funisitis was the most frequent pathological lesion (36%). Spirochetes were detected using silver and immunofluorescent staining in 89% of cords, including 92% of histologically normal and 84% of abnormal cords. Three specimens showed subamnionic aggregates of spirochetes, consistent with amniotic fluid infection. Necrotizing funisitis was strongly associated with umbilical artery infection by spirochetes (P = .008). There was a 100% correlation between results of silver and immunofluorescent staining. The umbilical cord is a sensitive site for morphological confirmation of T pallidum; it is significant for the pathologist that spirochetes may often be detected in the absence of overt tissue inflammation or necrosis.

Flow cytometric analysis of peripheral blood lymphocyte immunophenotypes in persons infected with Treponema pallidum.

To characterize the human immune response to syphilis, we determined the effect of infection with Treponema pallidum on the percentage of the various lymphocyte subpopulations in the peripheral blood of infected and uninfected persons. Monoclonal antibodies labeled with either fluorescein isothiocyanate or phycoerythrin were used to perform dual color analysis on a FACScan with the following markers: CD3 for total T cells, CD4 for T helper cells, CD8 for T suppressor cells, CD19 for B cells, and CD16 plus CD56 for natural killer cells. Lymphocyte immunophenotype results were analyzed by the stage of untreated syphilis and by gender. Although they were within the ranges of the normal distribution of immunophenotypes, the percentages of CD4+ cells were significantly lower (P < 0.001) and those of CD8+ cells were higher (P = 0.03) in patients with syphilis than in the uninfected population. For infected versus uninfected subjects, both women and men, the differences in the mean percentages of CD3+ and CD4+ cells were significant (P < or = 0.05). Significant differences were noted between the sexes in secondary syphilis only in the mean percentages of cells positive for CD3, CD4, CD8, and CD16 plus CD56. Gender had no effect on lymphocyte subpopulations in subjects with primary or latent syphilis. In the control population, significant differences due to gender were observed in the percentages of cells positive for CD3, CD4, and CD16 plus CD56.

Stability of immunofluorescence reactions produced by polyclonal and monoclonal antibody conjugates for rabies virus.

We investigated two consumer complaints that described fading of immunofluorescence reactions associated with the use of a commercial antirabies, fluorescein-labeled, monoclonal antibody conjugate. We compared the performance of this product with that of two polyclonal antibody antirabies conjugates and observed significant diminution of fluorescence with the monoclonal antibody conjugate only. Furthermore, the fading occurred only on tissue impressions that had been mounted but not exposed to UV light excitation, thereby essentially eliminating the photobleaching associated with fluorescence microscopy as a causative factor. Our observations suggest that mounting medium pH and the holding temperature of stained slides may be critical factors in maintaining optimal immunofluorescence reactions with this monoclonal antibody conjugate. We discuss some probable mechanisms that could produce the type of fading observed and also suggest certain precautionary measures for use with this monoclonal antibody conjugate.

Effect of adjuvant vaccines on dengue virus type 2 immune ascitic fluid production.

In a comparison of dengue type 2 immune mouse ascitic fluid immunization schedules, a schedule in which adjuvant vaccines were not used produced neutralizing antibody titers that were specific and a mouse mortality rate that was lower, resulting in a greater yield of ascitic fluids. In the schedules in which emulsified adjuvant vaccines were used, the quality of the emulsion had little effect on antibody titer produced.

Heated histoplasmin as a control for non-specificity in the complement fixation test for histoplasmosis.

We present data in support of the use of a heated histoplasmin control for the complement fixation (CF) test for histoplasmosis to assist in the detection of the presence of h or m antibody.