Evaluation of the Treponema pallidum particle agglutination technique (TP.PA) in the diagnosis of neurosyphilis.

The Treponema pallidum particle agglutination technique (TP.PA) was evaluated, in comparison with the Venereal Disease Research Laboratory (VDRL) test, microhemagglutination assay for Treponema pallidum antibodies (MHA-TP), and fluorescent treponemal antibody-ABS (FTA-Abs) test for the diagnosis of neurosyphilis. We have studied 198 cerebrospinal fluid (CSF) samples from patients with syphilis, including neurosyphilis, treated syphilis, and with other neurological manifestations than neurosyphilis. All tests were nonreactive in these last group of patients. In the neurosyphilis patients, sensitivity of the TP.PA was 100%. The performance of this test in CSF from patients with primary syphilis was as good as that of the other tests. In secondary and latent syphilis, the TP.PA results (27 reactive samples/73) were similar to those of the MHA-TP (25 reactive samples/73). In the individuals treated for syphilis, the TP.PA, FTA-Abs, and MHA-TP tests were found to be reactive in eight, six, and eight samples, respectively. In conclusion, it seems that the TP.PA can be used in CSF to diagnose neurosyphilis, although as for other serological tests, interpretation of results should be done in conjunction with other neurosyphilis parameters.

Evaluation of an enzyme immunoassay technique for detection of antibodies against Treponema pallidum.

In the present study, the performance of an enzyme-linked immunosorbent assay (ELISA) technique (Eti-syphilis-G and Eti-syphilis-M; DiaSorin) for detection of Treponema pallidum immunoglobulin M (IgM) and IgG antibodies for the laboratory diagnosis of syphilis was evaluated. Four hundred forty-one samples were studied. The sensitivity and specificity of the ELISA were 100 and 93%, respectively, compared with the results of a microhemagglutination assay for Treponema pallidum (MHA-TP) and 99.4 and 100%, respectively, compared with the results of the fluorescent treponemal antibody absorption (FTA-Abs) test. The results of the ELISA technique were concordant with those of MHA-TP for 98% of the samples tested, while the rate of concordance with the FTA-Abs test was 99.5%. The sensitivities of the rapid plasma reagin (RPR) test, MHA-TP, and the ELISA in the different phases of syphilis compared with the results of the FTA-Abs test were 92, 88, and 100%, respectively, for patients with primary syphilis; 100% for all tests evaluated for patients with secondary syphilis; 97.2, 99.4, and 100%, respectively, for patients with latent syphilis; and 57.9, 92.6, and 97.9%, respectively, for patients with past treated syphilis. The RPR test was reactive with 12 samples that were negative by all the specific tests. IgM antibodies were most frequently detected by the ELISA for IgM antibodies (32.8%) than by the FTA-Abs for IgM antibodies (28.4%). Detection of these antibodies by the FTA-Abs test and the ELISA for IgM antibodies decreased with the stage of disease (72 and 88%, respectively, for patients with primary syphilis to 17 and 19%, respectively, for patients with early latent syphilis). The high sensitivity and specificity of this ELISA technique during all stages of syphilis, together with the fact that it is a simple, objective, and easily automated method, lead us to believe that it could be used as a screening test for syphilis.