Syphilis – Chancre – Direct Fluorescence

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

Testing Indications

Direct fluorescence for detection of Treponema pallidum is indicated for the diagnosis of primary or secondary syphilis from suspected chancre or lesions.

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit


Serous exudates from lesion or chancre

Prepare 1 slide as directed in kit Instructions

Direct Fluorescence Kit for Treponema pallidum; Kit order number 390047

Submission and Collection Notes


Provide clinical information, onset date and the location of the lesion on the General Test Requisition Form.


Follow instructions according to specimen type on the kit instruction sheet for Syphilis – Direct Fluorescence Kit order# 390047.


A swab received in charcoal or antibiotic transport medium is not an acceptable specimen. If smears are prepared too thick or show signs of gross contamination with blood, they are unacceptable and the sample will not be tested. Submitter will be notified by telephone.

Due to the low sensitivity of the test, a blood sample should always be submitted for syphilis serology testing when syphilis is suspected.

Storage and Transport

Label slide with the patient’s full name and date of birth. Allow slide to dry and put it in slide mailer provided with the kit and place in a biohazard bag and seal. Failure to provide this information may result in rejection or testing delay.

Special Instructions

Specimens should be stored at 2-8 °C following collection and shipped to the Public Health Ontario Laboratory for testing. Avoid extreme temperature.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Direct fluorescence for syphilis is performed 2-3 times per week. 

Turnaround time is up to 2 days from receipt by PHO laboratory.

Test Methods

Smears from lesions or chancres for syphilis are tested by direct fluorescence.

The syphilis test detects spirochetes by fluorescent microscopy, however, due to the low sensitivity of the test, a negative result does not rule out syphilis.


Results are reported to the ordering physician or health care provider as indicated on the requisition.

Specimens that are positive for syphilis are reported to the Medical Officer of Health as per Health Protection and Promotion Act

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Updated 20 July 2020