Recovery of cytomegalovirus DNA from newborn saliva samples by different methods

Polymerase chain reaction (PCR) testing of saliva swabs has been shown to be an attractive method to screen for congenital cytomegalovirus (CMV) infection. However, few data are available regarding the impact of pre-analytic methods on CMV DNA recovery from saliva samples under various conditions.

The purpose of this study was to evaluate the impact of various transport media and transport conditions on the recovery of CMV DNA from spiked and clinical saliva samples from newborns using PCR testing.

Negative control saliva samples were spiked with known concentrations of World Health Organization CMV standards. Collection was simulated using filter paper and different types of swabs which were stored either dry or in various transport media at specified temperatures. Specimens were tested by quantitative PCR at multiple time points. Results were compared with samples taken from newborns infected with CMV using the same methods.

Nucleic acid stabilization media demonstrated superior CMV stability for up to 3 weeks. Also observed was a reduction in the quantity of spiked CMV DNA over time in swab samples stored at room temperature without media or in conventional universal transport media. Swab samples from newborns infected with CMV did not demonstrate loss of CMV DNA after a week of room temperature storage in nucleic acid stabilization media or conventional universal transport media.

Although nucleic acid preservation media appear to enhance CMV DNA recovery from spiked control samples over prolonged transport times and diverse conditions, this differential yield appears be to less significant for actual clinical samples collected from infected newborns. Further evaluation of pre-analytic conditions using actual clinical samples is warranted.