Dry saliva swab (DSS): a potential tool for the implementation of newborn ccmv screening

BRIEF INTRODUCTION A prompt virological diagnosis of congenital CMV infection (cCMV), testing valid samples as saliva, permits a proper follow-up of infected baby, then suitable interventions to reduce/prevent possible damages. Previously we showed that nylon-flocked swabs (DSS) are able to fully collect and release CMV-DNA from titrated viral suspensions. In this preliminary study, we evaluated different methods of DNA extraction from clinical Dry Saliva Swab (DSS) for CMV infection diagnosis. MATERIALS AND METHODS Three saliva swabs were collected from 244 unselected subjects (109 newborns, 135 infants) and 8 cCMV infected children (positive controls). The first one was immersed in VTM (Classic Saliva Swab, CSS) and subjected to thermal-shock (45s at 72°C, cooling and storage at -80°C), the others were kept without medium (DSS) until DNA extraction. All samples were tested through nested-PCR (gB gene). DSS were distinguished in two groups on the basis of DNA extraction method used, respectively thermal-shock as for SS (A) and vortexing (B). CLINICAL CASES OR SUMMARY RESULTS Results were positive in 34/244 (13,9%) and 8/8 (100,0%) cases, irrespective of extraction method. Sensitivity, specificity and concordance rates of each DSS group with CSS were >99%. CONCLUSIONS The results suggest that DSS could be an alternative sample for the identification of CMV infection. Ease of collection and handling, together with no-problem storage and inexpensive DNA extraction methods, make DSS a potential tool for the implementation of newborn cCMV screening.