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An aid in diagnosing adenovirus infections
Human adenoviruses cause a variety of diseases including pneumonia, cystitis, conjunctivitis, diarrhea, hepatitis, myocarditis, and encephalitis. In humans, adenoviruses have been recovered from almost every organ system. Infections can occur at any time of the year and in all age groups. Currently, there are 51 adenovirus serotypes that have been grouped into 6 separate subgenera.
Culture is the gold standard for the diagnosis for adenovirus infection; however, it can take up to 3 weeks to achieve culture results (Mayo's shell vial culture provides more rapid results, reported at 2 and 5 days). PCR offers a rapid, specific, and sensitive means of diagnosis by detecting adenovirus DNA.
A positive result indicates the presence of adenovirus nucleic acid.
A negative result does not rule out the presence of adenoviruses because organisms may be present at levels below the detection limits of this assay.
Test results should be used as an aid in diagnosis and should not be considered diagnostic in themselves.
Although the reference range is generally considered to be "Negative" for this assay, adenovirus DNA may be detected from asymptomatic individuals in certain settings. This assay should only be used to test patients with clinical history and symptoms consistent with adenovirus disease, and is not used to screen healthy patients.
The following data support the use of this assay for clinical testing.
Accuracy/Diagnostic Sensitivity and Specificity:
A study of 715 clinical specimens compared shell vial culture and this PCR assay. Included in the study were 286 swab specimens (nasal, throat, rectal, skin), 49 eye specimens, 221 respiratory specimens (bronchial washings, sputa, bronchioalveolar lavage, tracheal secretions), 55 fresh tissue specimens, 72 stools, and 27 body fluids/other specimens. Specimens were inoculated into culture tubes and examined for cytopathic effects over a period of 14 days, and subsequently assayed with this LightCycler assay. Comparison of cell culture with LC PCR yielded the following: total specimens positive by LC PCR was 60 (stool=9; respiratory=4; tissue=4; swabs=24; eye specimens=14; urine=4) and total specimens by culture were 52 (stool= 8; respiratory=3; tissue=3; swabs=23; eye specimens=13; urine=2). Of the 60 total positive specimens, PCR produced a 13.5% increased rate of detection of adenovirus compared with culture. Analytical sensitivity was assessed by testing dilutions (in triplicate) of the plasmid control down to a level corresponding to 1 target/microliter. The limit of reproducible detection was determined to be 10 targets/microliter. Additionally, the sensitivity of plasma was known to be > or =90% at the concentration of 10 targets/microliter. This assay detected all 51 serotypes of adenovirus tested.
Supplemental Data (Spiking Studies):
To supplement the above data, 30 negative samples of various types (cerebrospinal fluid, ocular, respiratory, stool, urine, and plasma) were spiked with adenovirus positive control plasmid at the limit of detection (approximately 10 targets/microliter). The 30 spiked specimens were run in a blinded manner with 30 negative (non-spiked) specimens. 100% of the spiked specimens were positive and 100% of the non-spiked specimens were negative.
Analytical Sensitivity/Limit of Detection (LoD):
The lower limit of detection of this assay is 10 targets/microliter in specimen matrix.
No PCR signal was obtained from extracts of 150 bacterial, viral, parasitic, and fungal isolates that could cause similar disease or could be found as normal flora in sites normally tested for this organism.
Inter-assay precision was 100% and intra-assay precision was 100%.
The reference range for this assay is "Negative."
This is a qualitative assay and results are reported as negative or positive for targeted adenovirus DNA.
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