antitreponemal

Antitreponemal refers to antibodies or immune responses directed against Treponema pallidum, the bacterium that causes syphilis. In a clinical context, antitreponemal antibodies are detected by treponemal-type serologic tests, including fluorescent treponemal antibody absorption (FTA-ABS), treponemal particle agglutination assays (TP-PA/TPPA), treponemal enzyme immunoassays (EIA), and chemiluminescent immunoassays. These tests are used to indicate exposure to T. pallidum and are distinct from non-treponemal tests that detect antibodies to cardiolipin, such as the rapid plasma reagin (RPR) and the Venereal Disease Research Laboratory (VDRL) test.

In diagnostic practice for syphilis, treponemal (antitreponemal) tests are typically used to confirm infection after an initial non-treponemal screening or as part of a reverse sequence algorithm where a treponemal test is used first. A reactive antitreponemal test suggests current or past infection with T. pallidum. Because treponemal tests often remain reactive for life, they are not reliable measures of ongoing disease activity or cure after treatment; non-treponemal test titers, which usually decline with successful therapy, are employed to monitor response.

Limitations of antitreponemal testing include occasional false-positive results in certain autoimmune conditions or other infections and the need to interpret results in the clinical and epidemiological context. Overall, antitreponemal testing remains a cornerstone for confirming exposure to Treponema pallidum in the diagnosis of syphilis.