Cytomegalovirus (CMV), Molecular Detection, PCR
Rapid qualitative detection of cytomegalovirus DNA
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Infection with cytomegalovirus (CMV) is a significant cause of morbidity and mortality in transplant recipients and other immunocompromised hosts, as well as neonates. Infection may involve multiple organs including the brain, lung, liver, and gastrointestinal tract.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Detection of cytomegalovirus (CMV) DNA in a specimen supports the clinical diagnosis of infection due to this virus.
Studies indicate that CMV DNA is not detected by PCR in cerebrospinal fluid from patients without central nervous system disease caused by this virus.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
A negative result does not eliminate the possibility of cytomegalovirus (CMV) infection.
This assay is only to be used for patients with a clinical history and symptoms consistent with CMV infection, and must be interpreted in the context of the clinical picture. This test should not be used to screen asymptomatic patients.
The following validation data support the use of this assay for clinical testing.
Accuracy and Diagnostic Sensitivity and Specificity:
LightCycler PCR (primers and probes directed to UL54 fragment of cytomegalovirus; CMV) was compared with shell vial cell cultures for the detection of CMV from 155 urine specimens. 142 specimens had concordant results between the 2 methods. Twelve specimens were positive for CMV by LightCycler PCR only and were confirmed by another PCR assay as true positives. Only 1 specimen was detected by the shell vial assay and not the LightCycler PCR.
In addition, 328 plasma specimens were tested by both the real-time LightCycler PCR assay targeting UL54 and a real-time PCR assay targeting the Hind IIIX region. Both detected 30 positive specimens and 296 negative specimens. The 2 discordant specimens were negative by the UL54 assay and positive by the Hind IIIX assay. These 2 specimens were positive by the UL54 assay on repeat testing, providing 100% concordance.
Fifty cerebrospinal fluid (CSF) specimens were tested by both conventional PCR and by real-time LightCycler PCR. CMV DNA was detected in 10 specimens by both amplification methods, and 40 specimens were negative for CMV DNA by both techniques (100% concordance).
Supplemental Data (Spiking Studies):
To supplement the above data, 30 negative specimens of all types acceptable for testing with this assay (urine, CSF, body fluids, dermal, tissue, respiratory; 180 total specimens) were spiked with CMV DNA plasmid control at the limit of detection (10-20 targets/mcL). The 30 spiked specimens from each group were run in a blinded manner along with 30 negative (nonspiked) specimens; 93% to 100% of the spiked specimens were positive and 100% of the nonspiked specimens were negative.
Analytical Sensitivity/Limit of Detection (LoD):
The lower limit of detection in this assay is <1,000 targets/mL (whole virus in specimen matrix).
No PCR signal was obtained from extracts of 44 bacterial and viral isolates including Epstein-Barr virus (EBV), herpes simplex virus (HSV), varicella-zoster virus (VZV), human herpes virus-6 (HHV6), HHV7, HHV8, and parvovirus.
Interassay precision was 100% and intraassay precision was 97%.
This is a qualitative assay and the results are reported as either negative or positive for targeted CMV DNA.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
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