Chlamydia trachomatis – Culture
Submission and Collection Notes
Unsuitable specimens: Urine and seminal fluid are not acceptable specimen sites for Chlamydia trachomatis culture. Dry swabs and swabs in bacteriological transport media (gel) are not acceptable collection kits for Chlamydia trachomatis culture and testing will not be performed.
Do not use expired kits.
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
Specimens should be stored at 2-8°C after collection and shipped on ice. Transport to the laboratory as soon as possible.
Specimens should be received at the testing laboratory within 48 hours of collection; this is especially important for neonatal and paediatric specimens. In situations of delayed transportation, specimens should be frozen at -70°C and transported on dry ice. Do not freeze sample at -20°C.
Test Frequency and Turnaround Time (TAT)
Chlamydia trachomatis specimens are tested 3 times per week.
Turnaround time is up to 7 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 (results from body fluids/aspirates, tissues, CSF or specimens from pregnant patients, infants, 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 are reported to the Medical Officer of Health as per the Health Protection and Promotion Act.
Specimens are tested using standard cell culture technique.
Interpretation
Results may be interpreted as positive, negative or toxic.
Toxicity may occur for various reasons including antibiotic therapy or high specimen pH and retesting may be required.
Additional Information
Medico-legal specimens
Culture is the specimen of choice for all potentially medico-legal specimens, i.e. pre-pubertal children, sexual abuse in peri-pubertal and pre-pubertal children, sexual assault and legal cases. Legal specimens should be transported to the laboratory under legal seal; contact the Medical Microbiologist prior to specimen collection.
Test of Cure (TOC)
Test of Cure for Chlamydia trachomatis/Neisseria gonorrhoeae is not routinely indicated. Repeat testing is recommended in the following scenarios:
- when compliance is difficult to ensure (e.g. failure to take or finish medication),
- if an alternative treatment has been used,
- in all pre-pubertal children,
- in all pregnant women, and
- in all cases of pharyngeal gonorrhea.
The optimal specimen for test of cure is culture and should be performed at 1 - 2 weeks after completion of treatment. If culture is not available, test of cure by NAAT will also be accepted and should be collected 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.
LGV testing
Male rectal specimens positive for Chlamydia trachomatis will be routinely forwarded to the National Microbiology Laboratory (NML) in Winnipeg for Lymphogranuloma venereum (LGV) testing. Specimens positive for Chlamydia trachomatis from other sources will only be sent if LGV testing is specifically requested.
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