Modification of CMV DNA detection from dried blood spots for diagnosing congenital CMV infection.
BACKGROUND
Detection of viral DNA in dried blood spots using the Guthrie card (DBS test) is a reliable and practical method of diagnosing congenital cytomegalovirus (CMV) infection. The test lends itself to epidemiological studies to establish the prevalence of the infection, but also to neonatal screening for secondary prevention of sequelae. These applications would be facilitated if it were possible to use smaller samples and do the test on pools of individual cases.


OBJECTIVE
To ascertain whether doing the test on smaller, pooled samples still accurately identifies neonates with congenital CMV infection.


METHODS
We tested DBS from: (A) 39 laboratory reference cases; (B) 156 neonates suspected of having congenital CMV infection; (C) 119 children examined for the retrospective diagnosis of congenital CMV; (D) mock specimens prepared with known amounts of viral DNA.


RESULTS
The test using only one third of the usual amount of dried blood was 100% sensitive and specific compared to the standard DBS test (A) and to viral isolation (A and B). Pools of three single cases gave the same results as viral isolation (B) and the small-sample test (B and C). All the versions of the test gave a detection limit of 400 copies/ml.


CONCLUSIONS
The modified procedure can accurately diagnose congenital CMV infection. It achieves savings in both the patient material and the costs of testing.
Binda
Sandro
S
Istituto di Virologia, Università di Milano, Via Pascal 38, 20133 Milan, Italy.
Caroppo
Simona
S
Didò
Patrizia
P
Primache
Valeria
V
Veronesi
Licia
L
Calvario
Agata
A
Piana
Andrea
A
Barbi
Maria
M
D001800:Blood Specimen Collection / Q000379:methods*; D002675:Child, Preschool; D003587:Cytomegalovirus / Q000235:genetics / Q000302:isolation & purification*; D003586:Cytomegalovirus Infections / Q000151:congenital* / Q000175:diagnosis* / Q000821:virology; D004279:DNA, Viral / Q000097:blood*; D006801:Humans; D007223:Infant; D016133:Polymerase Chain Reaction / Q000379:methods; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity
D004279:DNA, Viral; D011933:Reagent Kits, Diagnostic