Treponemal serologic tests

Definition

Treponemal serologic tests are blood tests used to detect antibodies specific to Treponema pallidum, the bacterium responsible for syphilis. These tests confirm the diagnosis of syphilis following a positive non-treponemal test.

5 Must Know Facts For Your Next Test

1. Treponemal serologic tests include the Fluorescent Treponemal Antibody Absorption (FTA-ABS) and the T. pallidum particle agglutination (TP-PA) tests.
2. These tests remain positive for life even after successful treatment of syphilis.
3. Treponemal tests are more specific than non-treponemal tests but may be less effective in distinguishing between active and past infections.
4. A positive treponemal test alone does not confirm an active infection; it must be interpreted with clinical findings and other diagnostic results.
5. The combination of a non-treponemal test (e.g., RPR or VDRL) followed by a treponemal test is the standard approach for syphilis diagnosis.

Review Questions

• What are two commonly used treponemal serologic tests?
• Why do treponemal serologic tests remain positive even after successful treatment?
• How should a positive treponemal serologic test result be interpreted?

Related terms

Non-Treponemal Tests: Screening blood tests like RPR and VDRL that measure reagin antibodies produced in response to cellular damage caused by syphilis.

Syphilis: A sexually transmitted infection caused by the bacterium Treponema pallidum.

Fluorescent Treponemal Antibody Absorption (FTA-ABS): A specific treponemal antibody test used to confirm a diagnosis of syphilis.