Question

A test used to identify antibodies against Treponema pallidum in a patient's serum is the

A) direct fluorescent-antibody test.
B) direct ELISA test.
C) hemagglutination-inhibition test.
D) indirect fluorescent-antibody test.
E) direct agglutination test.

Answer 1

The test used to identify antibodies against Treponema pallidum is the indirect fluorescent-antibody test (IFA). This test involves adding patient serum to T. pallidum cells on a glass slide and using a fluorescence microscope to visualize the bacteria if they have been bound by the antibodies. The option (D) is correct.

Step-by-step explanation:

The test used to identify antibodies against Treponema pallidum in a patient's serum is the indirect fluorescent-antibody test (IFA). In this test, T. pallidum cells are spread on a glass slide, and patient serum is added, which allows anti-treponemal antibodies, if present, to bind.

The slide is then washed and a secondary antibody conjugated to a fluorogen is added. The presence of T. pallidum bacteria can be visualized using a fluorescence microscope if they have been bound by the patient's antibodies. Therefore, option (D) is correct.