Chlamydia trachomatis/Neisseria gonorrhoeae (CT/GC) – Nucleic Acid Amplification Testing (NAAT) – Urine

Testing Indications

Urine specimens are the specimen of choice for males. In women who have had a hysterectomy, collect a first void urine for NAAT or a vaginal swab for culture or NAAT. 

For females in general, urine is a second-line option, because it is less sensitive than cervical and vaginal swabs for CT/GC NAAT. For  swab submissions,  refer to the test information sheet Chlamydia trachomatis/Neisseria gonorrhoeae (CT/GC) – Nucleic Acid Amplification Testing – Swabs for specimen collection and testing information.

 

Specimen Collection and Handling

Urine specimens are the specimen of choice for males and post-hysterectomy female patients.

For females in general, urine is a second-line option, because it is less sensitive than cervical swabs for CT/GC NAAT. For testing non-post-hysterectomy female patients, please refer to the test information sheet Chlamydia trachomatis/Neisseria gonorrhoeae (CT/GC) – Nucleic Acid Amplification Testing – Swabs for specimen collection and testing information.

Specimen Requirements

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

Chlamydia trachomatis/ Neisseria gonorrhoeae (CT/GC) NAAT or Chlamydia trachomatis (CT) NAAT

Urine (first catch) transferred to a Hologic® Aptima® Urine Transport tube

Transfer 2 ml of first catch urine from a sterile container to the Hologic® Aptima® Urine Transport tube between the black fill lines using the disposable pipette within 24 hours of collection.

PHO Chlamydia trachomatis & Neisseria gonorrhoeae Urine collection kit Kit order # 300209

Submission and Collection Notes

1

Collect 20-30 ml of urine (first catch) in a sterile container, then transfer 2 ml of urine from the sterile container to the Hologic® Aptima® Urine Transport tube between the black fill lines using the disposable pipette within 24 hours of collection. For details on specimen collection refer to the instructions located on the Hologic® Aptima® Urine Specimen Collection kit packaging. 

2

The Hologic® Aptima® Urine Transport tube Urine collection kits contain a preservative; the transferred urine must be between the black fill lines for accurate testing. 

3

Neat urines, and urine submitted in a kit other than the Hologic® Aptima® kit will be rejected. The Hologic® Aptima® Urine Specimen Collection kit is the only acceptable collection kit for testing.

4

The patient’s date of birth must be indicated on the General Test Requisition Form in order for the specimen to be processed for testing.

Limitations

NAA testing has not been validated for adolescents (less than 16 years), and medico-legal specimens (pre-pubertal children, sexual abuse in peri-pubertal and pre-pubertal children, sexual assault and legal cases). Culture for Chlamydia trachomatis and/or Neisseria gonorrhoeae from clinically appropriate sites is the method of choice in these cases – refer to the appropriate Test Information Sheet for culture.

Preparation Prior to 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.

Special Instructions

After collection, the urine must be stored and transported to the lab at 2-30°C within 30 days of collection.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Chlamydia trachomatis/Neisseria gonorrhoeae (CT/GC) NAAT urine specimens are tested daily, Monday to Saturday. 

Turnaround time is up to 3 days from receipt by PHO laboratory.

Reporting

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

Critical positive reports (specimens from pregnant patients, pre-pubertal children, i.e. ≤ 12 years and medico-legal specimens, i.e. pre-pubertal children, sexual abuse in peri-pubertal and pre-pubertal children, sexual assault and legal cases) are phoned and faxed if the client is registered for auto fax. 

Other positives are only faxed if client is registered for auto fax.

Specimens that are positive for Chlamydia trachomatis or Neisseria gonorrhoeae are reported to the Medical Officer of Health as per the Ontario Health Protection and Promotion Act.

Test Methods

NAA testing is available for Chlamydia trachomatis (CT) alone, or for duplex testing of Chlamydia trachomatis and Neisseria gonorrhoeae (CT/GC) simultaneously from one collection kit. Testing for Neisseria gonorrhoeae (GC) as a single test by Nucleic Acid Amplification is not performed and requests will be tested with the CT/GC combo assay.

Interpretation

NAAT results are interpreted as Detected or Not detected.

Data and Analysis

Additional Information

Test of Cure (TOC)

Test of Cure for CT/GC is not routinely indicated.  Repeat testing is recommended in the following scenarios: 

  1. when compliance is difficult to ensure (e.g. failure to take or finish medication), or suspected treatment failures,
  2. if an alternative treatment has been used, 
  3. in all pre-pubertal children, 
  4. in all pregnant women, and 
  5. in all cases of pharyngeal gonorrhea. 

The optimal specimen for test of cure is culture and should be performed 3-7 days after completion of treatment.   If culture is not available, test of cure by NAAT will also be accepted.  Test of cure by NAAT for GC should be performed 2 - 3 weeks after completion of treatment and for CT should be performed 3 - 4 weeks after completion of treatment. Chlamydia genetic material may persist for longer than 4 weeks and therefore must be considered when interpreting positive test of cure results.

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Contact Laboratory Customer Service

Laboratory Services

customerservicecentre@oahpp.ca

Updated 18 Jan 2019