Urine is the specimen of choice for neonates suspected of congenital cytomegalovirus (CMV) infection. Other viruses recovered from urine that may be representative of a systemic infection include enteroviruses, rubella, measles, and mumps. In addition, adenovirus may be cultured from urine specimens. If no virus is requested, urine specimens will be processed for CMV only. Additional cell lines or shell vials may be required if other specific viruses are requested. Refer to Appendix XV (Isolation and Identification) to ensure that the appropriate media is inoculated. Urine for which polyomavirus (BK or JC) is requested should be sent to the Public Health Laboratory (PHL) for electron microscopy.
II. Collection and Transport
The first morning voided urine sample is best for recovery of CMV. Urine should be collected in a clean, sterile container. If a delay in transport or processing is anticipated, keep the sample at 4oC.
A. Processing of Specimens:
Do not freeze the urine before processing. Urine can be left at 4º C for no more than 48 hours before inoculation. A fresh specimen should be requested from patients for which a urine is received that cannot be set up within this time frame (i.e. Friday evening, long weekends).
a) Gently mix and transfer 2 mL of urine to a sterile freezer vial. Add 4 drops gentamicin and 2 drops of fungizone to a final concentration of 100 µg/mL and 10 µg/ml respectively.
b) Allow to stand at room temperature for 10 minutes before inoculating
B. Direct Examination:
C. Isolation and Identification:
Incubation at 36oC
aMRC-5 = Human diploid fibroblast cells
b CMV-IE= Monoclonal antibody IFA stain for CMV immediate early antigen
Refer to Appendix II for Shell Vial staining and interpretation.
IV. Reporting Results
Shell Vial: Negative Report: “Negative for Cytomegalovirus.”
Positive Report*: “POSITIVE for Cytomegalovirus.”
1. Gleaves, Curt A. et al. Cumitech 15A “Lab Diagnosis of Viral Infections”.
American Society for Microbiology, August 1994