Syphilis – Serology

*Uncontrolled print copy. Valid only on day of print: 22 March 2023.

Testing Indications

Syphilis serology testing is indicated for routine diagnosis of suspected syphilis cases, monitoring of treatment of diagnosed syphilis, and as part of prenatal screening, and donor screening.

If ordering as part of a Prenatal Serology work-up, see Prenatal – Serology.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
Syphilis	General Test Requisition	Serum	2.0 ml	Blood, clotted-Vacutainer tubes (SST)

Submission and Collection Notes

For initial syphilis testing on newborns, it is recommended that maternal serum also be submitted with a separate requisition.

Two FULL red top or serum separator tubes (SST) are sufficient for testing all Hepatitis markers, HIV, HTLV, Syphilis and Rubella.

Do NOT submit glass tubes.

Limitations

Heat-inactivated, haemolysed, icteric, lipemic or microbial contaminated serum is not recommended for testing.
The screen test may be falsely negative in early infection.
Liquid anticoagulants may have a dilution effect resulting in lower concentrations for individual patient specimens.

Storage and Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay. Centrifuge if using SST. Place specimen in biohazard bag and seal. Specimens should be stored at 2-8°C following collection.

Specimens more than 7 days post collection will not be tested.

Special Instructions

Instructions for using SST tubes are found in the document titled: LAB-SD-008, Blood Collection using Serum Separator Tubes.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Syphilis screening is performed daily Monday to Friday.

Syphilis Confirmatory testing is performed daily Monday to Friday.

Turnaround time is up to 3 days from receipt by PHO laboratory for non-reactive samples and up to 6 days for Reactive samples.

Test Methods

All serum specimens submitted for syphilis testing are initially screened by CMIA (Chemiluminescent Microparticle Immunoassay). The CMIA test detects both IgG and IgM antibodies to Treponema pallidum.

If the CMIA is non reactive, the sample is reported as syphilis antibodies not detected.
If the CMIA is reactive, specimens will be tested for Rapid Plasma Reagin (RPR)
- If the RPR screen is reactive, the quantitative value will be provided, and no further testing is performed.
- If the RPR screen is non reactive, the Treponema pallidum Particle Agglutination (TPPA) test is performed unless performed previously

RPR is a quantitative non-Treponemal Flocculation Test that detects antibodies to cardiolipin-lecithin- cholesterol. The RPR titer decreases with treatment and/or time, and is most useful for assessing acute disease, monitoring treatment and identifying reinfection.

TPPA is a qualitative gelatin particle agglutination assay that is used for the detection and confirmation of Treponema pallidum antibodies (IgG and IgM) as an aid in the diagnosis of syphilis.