Treponema pallidum: Diagnosis


Diagnosis of Treponema Pallidum

  • Dark-field microscopy 
    • visualize motile spirochetes, which are too small to be seen on light microscopy
  • Labs
    • Nonspecific serologic screening
      • Both tests look for self-antibody that reacts with cardiolipin
        • Cardiolipin is released by cellular destruction by T. pallidum
      • Both tests are non-specific
        • falsely positive in SLE (anti-cardiolipin) and other conditions (pregnancy, rheumatic fever, etc.)
        • Used to screen due to cheap costs
      • VDRL (Venereal Disease Research Laboratory)
      • RPR (rapid plasma reagent)
    • Specific serologic confirmation
      • FTA-ABS (fluorescent treponemal antibody-absorption)  
      • Treponema pallidum enzyme immunoassay (TP-EIA)
    • Diagnosis of neurosyphilis: test CSF for VDRL, FTA-ABS, and PCR