Medicine & USMLE

Treponema pallidum: Diagnosis

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Bacteria - Gram Negative
  1. Neisseria spp: Overview
  2. Neisseria gonorrhoeae
  3. Neisseria meningitidis
  4. Haemophilus influenzae
  5. Bordetella pertussis
  6. Brucella
  7. Legionella pneumophila
  8. Pseudomonas aeruginosa: Overview
  9. Pseudomonas aeruginosa: Disease
  10. Salmonella Overview
  11. Salmonella typhi
  12. Salmonella enteritidis
  13. Shigella
  14. Yersinia enterocolitica
  15. Escherichia coli: Overview
  16. Enterohemorrhagic E. Coli (EHEC)
  17. Enterotoxigenic E. Coli (ETEC)
  18. Klebsiella pneumoniae
  19. Campylobacter jejuni
  20. Vibrio spp.
  21. Helicobacter pylori
  22. Borrelia burgdorferi (Lyme Disease)
  23. Leptospira interrogans
  24. Treponema pallidum: Overview
  25. Treponema pallidum: Diagnosis
  26. Congenital syphilis
  27. Chlamydia: Overview
  28. Chlamydia trachomatis
  29. Chlamydia pneumoniae vs. psittaci
  30. Rickettsia rickettsii
  31. Rickettsia typhi vs. prowazekii
  32. Anaplasma vs. Ehrlichia
  33. Coxiella burnetii (Q fever)

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