Cerebrospinal Fluid Treponema pallidum Particle Agglutination Assay for Neurosyphilis Diagnosis

摘要

There is no single sensitive and specific test for the diagnosis of neurosyphilis. The cerebrospinal fluid Venereal Disease Research Laboratory test (CSF-VDRL) is considered the “gold standard” test. While CSF-VDRL is specific, its sensitivity is 30 to 70% (1, 2). Conversely, CSF treponemal tests, in particular, the CSF fluorescent treponemal antibody absorption test (CSF-FTA-ABS), are more sensitive than CSF-VDRL, but they lack specificity (3). The sensitivities of CSF treponemal tests are greater than 90% when neurosyphilis is defined as a reactive CSF-VDRL and are lower when the diagnosis of neurosyphilis is based on clinical findings (3). Limited data on the use of the CSF Treponema pallidum particle agglutination assay (CSF-TPPA) for neurosyphilis diagnosis suggest that, like CSF-FTA-ABS, it may be diagnostically sensitive (4, 5). The Treponema pallidum hemagglutination assay (TPHA) is similar to TPPA, and two studies have suggested that a CSF-TPHA titer of ≥1:640 is specific for neurosyphilis diagnosis (6, 7). CSF-FTA-ABS requires a fluorescence microscope, while TPHA and TPPA are simpler flocculation tests whose results can be read by eye. The purpose of this study was to examine the sensitivity of CSF-TPPA for the diagnosis of laboratory and clinically defined neurosyphilis compared to that of CSF-FTA-ABS and to determine whether, like CSF-TPHA, a higher-titer cutoff value of the CSF-TPPA could be used to optimize the diagnostic specificity of the test. In addition, we aimed to compare the performance of CSF-TPPA in HIV-infected and -uninfected individuals with syphilis and to determine the impact of CSF red blood cell (RBC) contamination on diagnostic performance.