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Study shows saliva can be used for CMV screening in newborns
Boppana S. N Engl J Med. 2011;364:2111-2118.
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Saliva correctly identified every baby born with cytomegalovirus infection when liquid samples were used and 97.4% of babies when the samples were dried, according to research published online today.
The multicenter research project, led by University of Alabama at Birmingham (UAB) researcher Suresh Boppana, MD, and colleagues, aimed to find the most effective screening test for cytomegalovirus (CMV) infection in newborns. In an earlier study, the researchers concluded that a dried blood spot, such as that taken using the common heel stick technique, detected only 30% to 40% of babies with CMV infection and, therefore, was not an effective screening tool.
Nearly 35,000 infants in the well-baby nurseries of seven US hospitals were enrolled in the study between June 2008 and November 2009. Mouth swabs were taken when the infants were roughly 1 day old; the swabs were sent to UAB for testing. For the initial phase of the trial, the saliva samples were stored in solution; for the second phase, the swabs were air-dried.
Of the infants enrolled in phase 1, 85 infants were found to have CMV infection through both rapid culture method and polymerase chain reaction (PCR) detection; therefore, the sensitivity of PCR liquid samples was 100%. Of those newborns in phase 2, saliva rapid culture identified CMV infection in 76 infants, 74 of whom were identified with the saliva PCR; therefore, sensitivity of PCR dried samples was 97.4%. The researchers said the dry samples may be the best option for wide-scale screening because this method has high sensitivity, plus it is more efficient in terms of sample collection, storage and transport.
Sixteen additional samples were found to test positive for the saliva PCR samples but not for the saliva rapid culture. Follow-up testing revealed that three of these samples were indeed positive, leading the researchers to conclude that PCR may be a superior method to rapid culture for CMV screening. As for the remaining 13 samples, the researchers said CMV may have been present in the mother’s breast milk or secretions in the birth canal, which showed up in the baby’s mouth swab. For this reason, they said all positive screenings should be confirmed with follow-up testing within the first 3 weeks of age.
“We now know that we have a test with saliva that works,” Boppana said in a press release about the study. “The challenge is, unlike the dried blood spot, which is already used for newborn screening in hospitals across the country, we don't have a system in place for the collection of saliva. But we’ve shown that if you wanted to test a lot of babies for congenital CMV infection, it can be done.”
The researchers are now looking into how much congenital CMV infection contributes to overall hearing loss at birth and between the ages of 3.5 and 4 years. For this reason, infants who tested positive for CMV infection in the study are being enrolled in a follow-up program to monitor their hearing every 6 months until they are 4 years of age.
Disclosure: The research was funded by the National Institute on Deafness and Other Communication Disorders, part of the NIH. Dr. Boppana reports receiving consulting fees from GlaxoSmithKline.
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This is a very significant study that one day could lead to universal screening of newborns for congenital CMV infection. Approximately 40,000 neonates are born each year with congenital CMV infection, 8,000 of whom will develop sequelae (mostly hearing loss). Most of these babies do not have outwardly apparent symptoms at delivery, so screening for CMV is the only way to detect them. The CHIMES group has now developed a tool that can be used toward that effort. While significant programmatic issues remain before a screening program could or should be implemented, this critical first step has now been accomplished.
David Kimberlin, MD
Infectious Diseases in
Children Editorial Board member
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