Markers of past syphilis in HIV infection comparing Captia Syphilis G anti-treponemal IgG enzyme immunoassay with other treponemal antigen tests.

The sensitivity of the Captia Syphilis G anti-treponemal IgG enzyme immunoassay (EIA-IgG) was compared with the Treponema pallidum haemagglutination assay (TPHA) and the Fluorescent Treponemal Antibody Absorbed (FTA-Abs) test as a marker for past syphilis in 28 HIV-infected and 31 HIV-negative patients with a past history of syphilis. The specificity of EIA-IgG was compared in 89 patients without a history of syphilis who were known to be HIV antibody positive with a control group of 89 patients who had tested HIV negative. In patients with a past history of syphilis each treponemal test (EIA-IgG, TPHA and FTA-Abs) gave a lower sensitivity (82%, 86%, 79%) in the HIV-positive group than in the HIV-negative group (97%) but the difference was significant only in the case of the FTA-Abs test (P < 0.05). In the HIV-positive patients 11% (3/28) were negative in all 3 treponemal tests while 25% (7/28) were negative in at least one treponemal test. In patients without a past history of syphilis the EIA-IgG antibody index in the HIV-positive group (0.436) was significantly higher than in the HIV-negative group (0.378): the specificity, however, was similar in the HIV-positive (100%) and HIV-negative group (99%). We conclude that the Captia Syphilis G anti-treponemal IgG enzyme immunoassay is of similar specificity in HIV-positive and HIV-negative patients and is of similar sensitivity to the TPHA and FTA-Abs as a marker of past syphilis in HIV-infected patients.(ABSTRACT TRUNCATED AT 250 WORDS)