Question

Question #3: What is the purpose of absorbing the Pt serum with Reiter organisms first prior to testing?

Question #4: What specimen is used to test for neurosyphilis?

Answer 1

3). Produce increased sensitivity and specificity in the FTA test :

were made by two methods:

The absorption method,

consisting of using intact Reiter treponemes to

remove non-specific antibodies from the test serum;

and the blocking technique:

making use of rabbit Reiter treponemal antibody for binding or inac- tivation of T.pallidum common antigen receptor sites.

By absorption and blocking techniques,

removal of non-specific reactivity from the original

1: 5 FTA test established this non-specific reac-

tivity to be due to related treponemal antibodies.

This information to devel-oping an improved FTA test, the FTA-Absorption (FTA-ABS) test. (FTA-ABS Fluorescent treponemal antibody absorption test)

This new procedure is more than twice as sensitive as the FTA-200 test.

The absorbent for this test was prepared by disrupting Reiter trepo- nemes in a sonic oscillator and removing the coarse material by centrifugation.

The antigen for the FTA-ABS test is whole bacteria. The bacteria cannot be cultured on laboratory media, so the organisms used are a lyophilized suspension of T. pallidum extracted from rabbit testicular tissue.

This is spread over and fixed to a slide. Patient serum is mixed with an absorbent (the "ABS" part of the test) containing an extract of a non-pathogenic treponeme, Treponema phagedenis biotype Rieter.

The purpose of the absorbent is to remove anti-treponemal antibodies that are not specific for the syphilis bacteria.

The pre-adsorbed patient serum is then added to the slide; if the patient has been infected by syphilis, their antibodies will bind to the bacteria.

4).The VDRL test performed on cerebrospinal fluid (CSF) can be used to diagnose neurosyphilis in patients with a prior history of syphilis infection.

The presence of neurosyphilis in untreated patients can be detected by the presence of pleocytosis, elevated protein, and a positive VDRL.

The diagnosis of neurosyphilis depends on a combination of cerebrospinal fluid (CSF) tests (CSF cell count or protein and a reactive CSF-VDRL) in the presence of reactive serologic test results and neurologic signs and symptoms.