Diagnosis of congenital cytomegalovirus infection in newborn dried blood spots on Guthrie cards.: A promissory technique

Laboratories play a crucial role in the diagnosis of congenital and perinatal cytomegalovirus infection, considering that other viral infections in newborn infants have similar clinical characteristics. The objectives of this work are to compare the results of the polymerase reaction in blood spots and urine as well as point out the relevance of the result in the Guthrie cards to differentiate congenital from perinatal infection. A total of 148 patients suspicious of CMVH infections were studied in the Congenital Perinatal Infections and Sexual Transmission Laboratory, at the National Institute "Carlos G. Malbran". The dry blood samples ( Guthrie cards) and urine of all patients were studied through the polymerase chain reaction. From the 148 patients, 3 presented other infections, 95 tested negative and 50 positive for cytomegalovirus: 35 had congenital infection and 15 perinatal. In the congenital cases, the polymerase reaction in dry blood was positive ( sensitivity 100%, specificity 98.9%, VPP 98% and VPN 100%). Four of them with tardive symptoms were studied retrospectively. The urine specimens from the remaining 15 patients that were taken 15 days after birth were analyzed through the same methods, showing a sensitivity of 100%, the retrospective analysis of this dry blood group yielded negative results, so the infection was considered perinatal. Thus, the dry blood polymerase reaction of the newborn infants makes it a reliable assay for diagnosing congenital cytomegalovirus infection and could be used as an alternative method to urine polymerase reaction. In addition, this test is able to reveal whether the infection is congenital or perinatal in those cases of late symptom or other cases of controversial origin.