CDC Reverse Sequence Algorithm: Treponemal test first, then non-treponemal. Discordant results require confirmatory TPPA.
Step 1: Treponemal Test (EIA/CIA)
Guidelines & Evidence
Clinical Details
Section 1
CDC Algorithm
Step 1: Treponemal Test (EIA/CIA)
Reactive → Proceed to Step 2. Non-reactive → Syphilis unlikely (unless very early primary).
Step 2: Non-treponemal Test (RPR/VDRL)
Reactive → Syphilis confirmed. (Evaluate for stage and treatment history).
Step 3: Discrepancy (Step 1+/Step 2-)
["Perform a different treponemal test (TPPA).","TPPA(+): Past treated syphilis OR late latent/tertiary syphilis.","TPPA(-): False positive EIA/CIA; Syphilis unlikely."]
Section 2
Management Triage
Primary/Secondary/Early Latent (<1y)
Benzathine Penicillin G (Bicillin L-A) 2.4 million units IM x 1.
Late Latent (>1y or Unknown)
Benzathine Penicillin G 2.4 million units IM weekly x 3 weeks.
Neurosyphilis
Aqueous Crystalline Penicillin G 18–24 million units/day IV (3-4 million units q4h) for 10–14 days.
