Author: admin, 03.09.2014Discharges are characterized by color (clear, white,green, gray, yellow), consistency (thin, thick, curdlike), andamount (more or less than usual). 1°-papule which ulcerates, then lymph nodes2°-6-20 weeks, maculopapular symmetrical rash on palms and soles. Condyloma Lata (flat warts) 3°-Tabes dorsalis. Serologic testing is by definition an indirect method of diagnosis since it relies upon a humoral immune response to infection. In order for this test to be useful, it must be performed by someone experienced in the identification of T. This test requires a fluorescence microscope and a trained and experienced technologist; it is not widely available in most clinics seeing patients with STDs. There are two types of serologic tests for syphilis: nontreponemal tests such as the Venereal Disease Research Laboratory (VDRL) test and the Rapid Plasma Reagin (RPR) test, and treponemal tests such as the fluorescent treponemal antibody absorption (FTA-ABS) test, the microhemagglutination test for antibodies to Treponema pallidum (MHA-TP), and the Treponema pallidum particle agglutination assay (TPPA).
These tests measure IgG and IgM antibodies and are used as the screening test for syphilis in most settings. Positive tests are usually reported as a titer of antibody, and they can be used to follow the response to treatment in many patients. The task force recommended against routine screening of asymptomatic persons who are not at increased risk of syphilis, since most positive tests in this setting represent false positive and can lead to unnecessary anxiety for patients as well as increased costs and potential harm from inappropriate antibiotic use.
The use of a single serologic test to diagnose syphilis is generally inadequate because of the potential for false-positive results . It is highly unlikely that any one patient will have false positive tests using both reagin and treponemal techniques.
Thus, the usual testing algorithm is to screen with a nontreponemal test such as the VDRL; a reactive specimen is then confirmed as a true positive with a treponemal test such as the FTA-ABS. An understanding of the proper interpretation of these tests is essential to their effective use. In addition to false positive tests, false negative results may also complicate serologic diagnosis.
Probably the most common cause of a false negative syphilis serologic test is performance prior to the development of diagnostic antibodies (show figure 2). Twenty to 30 percent of patients presenting with a chancre will not yet have developed a reactive serologic test for syphilis . This phenomenon affects nontreponemal tests and occurs in less than 2 percent of samples, almost always during secondary syphilis when antibody titers are the highest. Laboratory technologists may suspect its presence when an apparent nonreactive test exhibits a rough or granular appearance .
It is important that the same testing method (eg, RPR or VDRL) be used for all follow-up examinations since titers may vary by 1 to 2 dilutions if different tests are used.
Several factors may influence the rate at which titers decline following therapy, including prior episodes of syphilis, the duration of infection prior to therapy, and the pretreatment antibody titer [1,15]. Up to 25 percent of patients with late neurosyphilis have nonreactive serum reagin antibody tests, presumably due to a loss of the antibody response to T.
Current Centers for Disease Control and Prevention (CDC) recommendations suggest that CSF examination should be performed in persons with latent syphilis and any of the following (show table 2) : Ophthalmic signs or symptoms Evidence of active tertiary syphilis Treatment failure (including failure of nontreponemal tests to fall appropriately) HIV infection with late latent syphilis or syphilis of unknown duration The optimal approach in patients with none of these findings is uncertain.
Treponemal tests are not usually recommended for CSF samples, although they may be useful in ruling out neurosyphilis.
However, some patients with very late stage HIV infection have delayed or absent serologic responses to syphilis (ie, false negative tests) [23,24] or are more likely to lose their reactivity after appropriate therapy [25,26].
Presumably due to HIV-induced abnormalities in B-cell function, HIV-infected individuals who do not have syphilis have a greater incidence of falsely reactive nontreponemal tests than those without HIV infection [27-29]. Interestingly, subsequent analysis of some of the HIV-infected persons with apparent false positive nontreponemal tests suggested that a proportion of such cases actually were due to failure of the treponemal test (FTA-ABS) to detect true infection . In one series of 35 patients who had at least one positive RPR test with a nonreactive FTA-ABS, five converted to a reactive FTA-ABS test; in addition, some patients who remained nonreactive by FTA-ABS had antibodies to T. Thus, patients may represent false negative FTA-ABS reactions in HIV-infected patients with latent syphilis rather than biologically false positive nontreponemal tests in persons who do not have syphilis. In contrast to these findings, a prospective trial of therapy in 525 patients with syphilis found that the presence of HIV infection did not influence the performance of treponemal tests . The conflicting data illustrate the difficulty of having to rely upon serologic tests for the diagnosis of any infectious disease.
While clinicians should remain vigilant for exceptional cases, the management strategies outlined in published guidelines appear to be reasonable and appropriate for all patients .
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