Usefulness of Cytomegalovirus (CMV) DNA Detection in Dried Urine and Saliva Samples for Neonatal Screening of Congenital CMV Infection

Background: CMV is the leading cause of congenital infection in humans, occnrring in 0.2 to 2.5% of all livebirths. Congenitally infected infants, both symptomatic and asymptomatic at birth, may develop sequelae, particularly hearing loss and brain damage. Therefore, universal newborn screening for CMV should be recommended to detect sequclae as caliy as possible. Aim: Te evaluate the usefulness of dried urine samples (DUS, Dried Urine Spot test) and dried saliva samples (DSS, Dried Saliva Samplc test) for detecting CMV by nested PCR, compared with the use of liquid urine and of saliva in medium, for a neonata! screening. Design/Methods: Phase 1: both DUS and DSS tests were validated in our laboratory, using negative and positive controls. Positive controls were prepared from negative specimens artificially infected with a CMV Towne strain. Phase 2: we studied all the infants born at our hospital during the study period, whose parents gave informed consent. Liquid and dried urine and saliva samples were collected within the first 2 wks of life. Dried urine was obtained using filter papers placed in the diaper, dried saliva was collected using a swab transfcrred to a sterile tube without medium. All the liquid specimens were tested for CMV by "shell-vial" culture (SVC) and by nested PCR, all the dried specimens were tested by nested PCR. In a group of infants CMV-DNA PCR was also performed on Guthrie card (DBS, Dried Blood Spot test). Results: We enrolled 338 neonates: mean GA 36.4 wks, mean 13W 2676 g. We examined 1652 samples in total. CMV was detected in liquid urine by SVC in 8/338 (2.3%) neonates, and those were diagnosed as congenitally infected. 4/8 (50%) infected infants were symptomatic at birth. ln all infants with congenita! infection, viral DNA was detected in urine and saliva samples, both liquid and dried, by nested PCR. DBS test, performed in 4/8 neonates, confirmed the diagnosis of congenital infection. Conclusions: According to our results, a test based on detection of viral DNA by PCR in dried urine and saliva samples appears a reliable method for the diagnosis of congenita! CMV infection.