Chlamydia trachomatis – Lymphogranuloma venereum (LGV) PCR

Testing Indications

All LGV requests are first tested for Chlamydia trachomatis (CT) by either culture or Nucleic Acid Amplification Testing (NAAT), depending on the kit type received. Specimens that are negative for CT will not be sent for further testing. LGV PCR should not be used for CT screening.

Rectal bacterial sexually transmitted infections, including CT and NG (Neisseria gonorrhoeae), have been associated with increased risk of HIV infection in gay, bisexual, and other men who have sex with men, and transgender women.  Screening for HIV is highly recommended in these individuals. Details about HIV serology testing at PHO can be found on the HIV Serology Test Information Sheet. Consider initiation of Pre-Exposure Prophylaxis (PrEP) for HIV-negative individuals. For more information on PrEP, refer to ontarioprep.ca.

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.

Specimens for CT culture should be stored at 2-8°C after collection and shipped on ice as soon as possible. Specimens should be received at PHO’s laboratory within 48 hours of collection. If transportation will be delayed, specimens should be frozen at -70°C and transported on dry ice. Do not freeze samples at -20°C.

Specimens collected in the Roche cobas^® PCR Media for NAAT must be stored and transported to PHO’s laboratory at 2-30°C. Specimens in the Roche cobas^® PCR Media are stable within 12 months of collection.

Special Instructions

Complete all fields of the General Test Requisition Form. Include, the patient’s full name, date of birth, Health Card Number (must match the specimen label), enter the name of the test requested under test description, source of specimen, date of onset, date of collection, physician name and address, and clinical diagnosis. LGV must be indicated on the requisition for testing to be performed.

Kits (order using the Requisition for Containers and Supplies):

• CHL(C) kit/Chlamydia trachomatis culture kit order #390083 (female) or #390084 (male)
• Chlamydia trachomatis & Neisseria gonorrhoeae Roche cobas® PCR Media Dual Swab Sample Kit order #300317
• Chlamydia trachomatis & Neisseria gonorrhoeae Roche cobas® Urine Collection Kit order #300316

Test Frequency and Turnaround Time (TAT)

After initial testing at PHO’s laboratory, positive CT specimens requesting LGV testing are shipped every Wednesday to the National Microbiology Laboratory (NML) for testing.

Turnaround time is up to 28 days from receipt by PHO’s laboratory.

LGV PCR is referred to the National Microbiology Laboratory (NML) in Winnipeg. Detection of LGV is performed using multiplex real-time PCR. The serovar is confirmed by amplification and sequencing of the ompA gene and the pmpH gene.

For more information, refer to: Chlamydia trachomatis – Lymphogranuloma venereum (LGV) PCR Molecular Detection and Genotyping.

Algorithm

Only CT-positive specimens are referred to the NML for LGV testing. Specimens submitted for LGV are screened by PHO’s laboratory by culture or NAAT, depending on the specimen type/kit received.

• Culture: specimens are tested using standard cell culture (refer to the CT - Culture Test Information Sheet). Negative cultures will be resulted after 48 hours and LGV testing will not be performed. 
• NAAT: specimens submitted in Roche cobas^® PCR Media are tested using the Roche cobas^® CT/NG NAAT (refer to the CT/NG NAAT Test Information Sheet). LGV testing will not be performed on CT-negative specimens.

All NML LGV results will be sent as a reference attachment to the PHO report.

Interpretation

LGV genotype will be reported.

Reporting

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

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

Preliminary positive LGV results will be reported when received from the NML. Results are only faxed if client is registered for auto fax. A final report will be sent upon completion of the genotyping testing performed at NML.

References

LAB-SD-005, Chlamydia trachomatis and Neisseria gonorrhoeae - Nucleic Acid Amplification Testing