Cytomegalovirus Detection – Real Time PCR
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This page provides diagnostic PCR testing information for Cytomegalovirus (CMV) detection at Public Health Ontario (PHO). This page also provide information on PHO referred out test for CMV antiviral resistance genotyping.
For information regarding other testing options, refer to the following PHO webpage:
Updates
- Added information for CMV antiviral resistance genotyping test
Testing Indications
The CMV qualitative PCR is indicated for the following clinical scenarios:
- Evaluation of a newborn for congenital CMV infection.
- Screening for CMV disease in immunocompromised patients or critically ill (e.g. admitted to ICU) immunocompetent patients where CMV disease is suspected. Positive qualitative PCR tests should be followed up with a quantitative CMV PCR test, which is not available at PHO’s laboratory. If available, testing these patients with a quantitative PCR test as the primary testing approach is preferred.
Resistance testing, performed by the National Microbiology Laboratory in Winnipeg (NML), is indicated for suspected anti-viral resistant HCMV (Human Cytomegalovirus), characterized by no improvement (or relapse) in CMV viremia or clinical disease during antiviral therapy (for 6 or more weeks)
Acceptance/Rejection Criteria
Blood/serum specimens will not be accepted for CMV PCR testing.
Specimen Requirements
| Test Requested | Required Requisition(s) | Specimen Type | Minimum Volume | Collection Kit |
Cytomegalovirus PCR |
Bronchoalveolar lavage (BAL)/ |
2.0 ml |
Sterile container |
|
Cytomegalovirus PCR |
Urine |
2.0 ml |
Sterile container |
|
Cytomegalovirus PCR |
CSF6 |
400 µl |
Sterile container |
|
Cytomegalovirus PCR |
Tissue (e.g. Lung) |
1.0 gram |
Sterile container |
|
HCMV antiviral resistance genotyping4 |
HCMV positive plasma, or |
1.0 ml |
Plasma Preparation Tube (PPT) or K2EDTA tube (plastic; lavender or pink top)5 |
|
Cytomegalovirus PCR Confirmation of CMV DNA detection on newborn screen test. |
Urine |
2.0 ml |
Sterile container |
Submission and Collection Notes
Complete all fields of the requisition form, including:
- Test(s) requests and indications for testing
- Patient setting/population/source
Label the specimen container(s) with the patient’s first and last name, date of collection, and one other unique identifier such as the patient’s date of birth or health card number. For additional information see: Criteria for Acceptance of Patient Specimens. Failure to provide this information may result in rejection or testing delay.
Place specimen in biohazard bag and seal.
For HCMV antiviral resistance genotyping, the specimen should be positive for HCMV DNA and results included with the requisition form.
Do not use heparin as an anti-coagulant
Cerebral Spinal Fluid (CSF) specimens have not been validated with this assay, results are reported with a disclaimer.
Storage and Transport
Specimens should be stored at 2-8°C following collection and shipped to PHO’s laboratory on ice packs. If transport is delayed for more than 72 hours, store at -80°C and ship on dry ice.
For HCMV antiviral resistance genotyping specimens: Do not freeze whole blood; store and ship refrigerated within 48h of sample collection. Plasma may be stored and shipped refrigerated to NML within 48h of sample collection or must be stored and shipped frozen. Viral cultures must be stored frozen at all times and shipped on dry ice.
All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.
Test Frequency and Turnaround Time (TAT)
Cytomegalovirus PCR is performed Monday, Tuesday and Thursday at PHO’s laboratory.
Turnaround time (TAT) for CMV real-time PCR is up to 3 business days from receipt at PHO’s laboratory.
CMV antiviral resistance genotype TAT is 10 calendar days upon specimen receipt at NML.
STAT and Critical Specimens Testing
STAT testing for CMV PCR at PHO is not available. Urgent testing under special circumstances is available for CMV antiviral resistance genotype at NML. Please contact NML for additional details.
Specimens are tested for CMV by real-time PCR (qualitative real-time PCR) using Altona RealStar® CMV PCR Kit 1.0 at PHO. This commercial assay is not Health Canada approved but has been validated at PHO’s laboratory for qualitative detection of CMV DNA in clinical specimens. The manufacturer has reported a limit of detection of 0.668 IU/ml (95% CI 0.323 to 2.258 IU/ml) using the ABI 7500 FAST SDS system.
CMV antiviral resistance genotyping is performed at the National Microbiology Laboratory (NML).
The laboratory performs genotyping and comparative genomic studies of viruses, and antiviral resistance for CMV.
Refer to NML for more information - Antiviral Resistance Genotyping – CNPHI
Interpretation
Results will be reported as DETECTED/ NOT DETECTED/ INDETERMINATE for CMV-PCR
The presence of CMV DNA in a sample does not always imply active infection; the diagnosis of CMV infection must be made using a combination of clinical suspicion, physical exam and detection of virus.
An indeterminate PCR test result may be due to a low level of target genetic material in the specimen, inadequate specimen content, or a non-specific signal. For indeterminate results, consider resubmitting another specimen if clinically indicated.
Interpret antiviral resistance genotyping results with caution as this assay is for research purposes only. Refer to NML for more information - Antiviral Resistance Genotyping – CNPHI
Reporting
Results are reported to the ordering physician, authorized health care provider (General O. Reg 45/22, s.18) or submitter as indicated on the requisition.
CSF specimens that are positive for cytomegalovirus are reported to the Medical Officer of Health as per the Ontario Health Protection and Promotion Act.
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