Syphilis (Part 3)

Written by: Solaris Diagnostics

Treponemal Tests and Reverse Sequence Algorithm

Most patients who have reactive treponemal tests will have reactive tests for the remainder of their lives, regardless of adequate treatment or disease activity. However, 15%–25% of patients treated during the primary stage revert to being serologically nonreactive after 2–3 years (570). Treponemal antibody titers do not predict treatment response and therefore should not be used for this purpose.

Clinical laboratories sometimes screen syphilis serologic samples by using automated treponemal immunoassays, typically by EIA or CIA. This reverse sequence algorithm for syphilis testing can identify persons previously treated for syphilis, those with untreated or incompletely treated syphilis, and those with false-positive results that can occur with a low likelihood of infection. Persons with a positive treponemal screening test should have a standard quantitative nontreponemal test with titer performed reflexively by the laboratory to guide patient management decisions. If the nontreponemal test is negative, the laboratory should perform a treponemal test different from the one used for initial testing, preferably TP-PA or treponemal assay based on different antigens than the original test, to adjudicate the results of the initial test.

The improved Solaris Diagnostics laboratory Syphilis Screening approach is provided in Figure 2 which provides the following advantages. 

  • Treponemal IgG screening tests are highly sensitive and specific. 
  • Fewer false negatives than non-treponemal assays, presumably due to detection of latent syphilis. 
  • Increased testing volume while reducing manual labor.  
  • More effective for diagnosis of secondary, latent, and late syphilis as they are not subject to prozone reactions, which have been reported as a rare occurrence in nontreponemal (RPR) assays. The high antibody titer which interferes with formation of antigen-antibody lattice needed to visualize a positive flocculation or clumping test. Prozone effect is most often associated with secondary syphilis, HIV co-infection and pregnancy.


Share this Article

Recent Articles

Haemophilus Influenzae

  Haemophilus influenzae is the name for any illnesses caused by the bacteria H. influenzae, the most common type of Haemophilus influenzae is Haemophilus influenzae

Read More »

Coxiella Burnetii

  Coxiella burnetii is a bacterium isolated from ticks. It is a gram-negative bacterium which causes an infection called Q fever that infects the respiratory

Read More »

Fungal Nail Infections

Fungal nail infections are common infections caused by the overgrowth of fungi which disrupt the environment of the toenail or fingernail through small cracks in

Read More »

Chlamydia Trachomatis

  Chlamydia Trachomatis is one of the more common sexually transmitted infections. The bacterial infection has a higher prevalence in populations aged 15-24, with women

Read More »


Antibiotic resistance is a serious topic in the medical community, as new drugs are developed and used for the treatment of infections these bacteria have

Read More »

Need a Reliable Diagnostic Partner?

At Solaris Diagnostics, we make it easy!

Our Results Portal allows you access patient reports quickly and securely online.

To request access to the Providers Results Portal, please complete our Provider Registration form.

Scroll to Top