Test: virus cultures
Viruses that grow in culture include: adenovirus, cytomegalovirus, herpes simplex virus, enterovirus, varicella zoster virus, influenza virus, parainfluenza virus, respiratory syncytial virus, rhinovirus, mumps virus.
What needs to be on the label?
The specimen container must be labeled with the patient name, MSP number, specimen type and date and time of collection
What happens if the specimen is unlabeled?
An unlabelled specimen will not be processed, unless it is a specimen which is difficult or impossible to collect again, in which case a discussion will be had with the referring doctor
What needs to be on the requisition?
Each specimen must be accompanied by a requisition slip containing the same information as on the specimen, the clinical diagnosis, date of onset of illness and, for serology requests, information about previous blood transfusions. The more detailed information on the requisition, the easier it is to narrow the tests performed and to interpret the test results. For specific queries regarding specimen collection and transport please call the virus laboratory at 604-875-2345 ext. 7463. For prompt reporting, please include telephone/fax number of referring doctor/clinic.
What type of specimen do I collect?
Blood, cerebrospinal fluid, skin scraping, eye swab, genital swab, mucosal swab, oral swab, rectal swab, nasopharyngeal washing, stool, tissue, urine, biopsy. For specific information about the best specimen to collect for a specific virus, please call the virus laboratory at 604-875-2345 ext.7463
When do I collect the specimen?
If in hospital, collect the specimens fresh early in the morning and bring straight to the laboratory.
What volume is required? N/A
Is there a minimum volume? No
How do I collect the specimen?
Always consult the laboratory for specific details prior to collecting specimen for biopsy. For biopsies, please notify the laboratory in advance. Specimen should be collected during the acute phase of the illness as follows:
- Nasopharyngeal washing: Insert a baby feeding catheter (attached to a syringe containing 1 ml sterile saline, .5 ml for babies) into one nostril. Express the saline and draw it back into the syringe. Transfer specimen to sterile container and deliver immediately to the virus laboratory. Specimens arriving with a mucous trap attached will not be accepted. Ideally the specimen should be collected early in the morning and arrive early in the laboratory.
- Throat swab: Only appropriate for herpes virus culture. Carefully rub the postural wall of the nasopharynx with a dry, sterile swab. Avoid touching the tongue or buccal mucosa. Specimens are to be collected into virus transport media (available in a kit from the virus laboratory)
- Blood: Collect 5 ml whole blood into heparinized tube. Consult laboratory as to which specimen will be sent for specific recommendations.
- Stool: Collect 4 - 8 grams of stool (about the size of thumbnail) and place in a clean leak-proof container. Do not dilute the specimen (into virus transport medium) or use preservatives.
- Rectal swab: Insert a sterile swab two to four inches into the rectum and rub the mucosa. Swab may be placed into cold virus transport medium available in a kit from the virus laboratory.
- Cerebrospinal fluid: Collect 1 ml of CSF aseptically into a sterile dry screw-cap vial.
- Vesicular skin lesions: Open the vesicle and swab the lesion, put swab into virus culture medium. Or, if enough vesicle fluid is available, aspirate the fluid with a fine gauge needle and tuberculin syringe and place the fluid into cold viral transport medium. De-roof the vesicle and vigorously scrape the base of freshly exposed lesion with a scalpel blade to obtain cells that contain viruses. Smear the scraped material onto a immunofluorescence slide, which is available from the virus laboratory. If collection kit is available from the virus laboratory, a fixative is included, if you have time, use the fixative. Otherwise send the slide unfixed to the laboratory. If you do not have access to appropriate slides, it is possible to use ordinary glass slides (do not have to be sterile), and just smear out in a very small area about the size of a penny. Send to virus laboratory.
- Urine: collect clean catch, mid-stream urine in a leak-proof sterile plastic container. A urine specimen is appropriate when you wish to detect mumps virus, adenovirus or cytomegalovirus.
- Tissue: use a fresh set of sterile instruments to collect each tissue. Place each specimen in its own dry, sterile non-toxic leak-proof container. Identify each tissue with patient's name, type of tissue and date collected.
- Eye swab or scraping: Use a swab to collect conjunctival material or take conjunctival scrapings with a fine sterile spatula and transfer the scraping to a vial transport medium.
- Biopsy: Swab in virus transport medium; biopsy in sterile containers.
Is a special transport medium required?
- Viral transport medium (available from virus laboratory)
- Swabs, sterile screw cap tube or container for fluids, stool, nasal washings, urine, or biopsy (without preservative)
- Green top tube for blood, bone marrow and occult blood
How do I transport and store the specimen?
Transport specimen to the laboratory immediately. If this is not possible, keep specimen cold and moist. Do not freeze specimens at -20oC; if necessary store them at 40oC - 60oC or if possible at -700C. Causes for rejection: dry specimen, specimen not in proper viral transport medium, specimen not refrigerated during transport, specimen not received in sterile, excessive delay in transport, mislabeled and unlabeled specimens, leaking specimens.
When will I have a result?
The presence of viruses in culture is usually suggested by the characteristic cytopathic effect (CPE) they cause when they infect cell cultures. CPE (and therefore, positive results) can be observed as soon as one day and as late as six weeks post-inoculation of the cell culture. It is important for the appropriate interpretation to inform the laboratory about specific virus suspected, specific site of specimen, age and sex of patient and relevant vaccinations and clinical history.
If you need to refer the specimen, where does it go and when will I have the result?
In rare instances, specimens have to be referred to the provincial laboratory for virus culture. This is the case for rubella and measles, for example. The turnaround time will vary depending upon the specific virus being cultured. Rubella culture takes 14-16 days and measles culture takes between 20-22 days.
What are the limitations of this test?
Not all viruses grow in culture, the results may be delayed due to the time it takes for detection and if inappropriate transportation occurs virus may not grow at all. Please contact the microbiologist is you have any specific questions
Who do I call if I have questions? The microbiology laboratory (7460), the virology laboratory (7463) or page the microbiologist on call through the switchboard.
