Comparison of conventional, immunological and molecular techniques for the diagnosis of symptomatic congenital human cytomegalovirus infection in neonates and infants.

PURPOSE

Human cytomegalovirus (HCMV) is the commonest pathogen causing congenital infection globally. The diagnosis of congenital infection is based either on viral isolation (in cell culture) or demonstration of HCMV DNA from the urine. Saliva is also being used as an alternative sample to urine for the same. The objective of this study was to compare the following assays-polymerase chain reaction (PCR) from urine, saliva and blood, serology (anti-HCMV IgM) and antigen detection (HCMV pp65 antigenaemia) for the diagnosis of congenital HCMV infection.

MATERIALS AND METHODS

Urine and blood samples were collected from 31 infants (median age: 13 weeks) with suspected HCMV infection. For 18 infants, additional saliva samples were collected and all the above assays were compared.

RESULTS

PCR for HCMV DNA from urine and anti-HCMV IgM were performed for all 31 infants. Of these, 22 (70.9%) were positive for both assays. In 18 (of the 22) infants positive by both assays, PCR for HCMV DNA from saliva was positive in all 18 (100%), PCR from blood in 7/18 (38.8%) and HCMV pp65 antigenaemia only in 1/18 (5.5%) of the infants.

CONCLUSION

Detection of HCMV DNA in urine combined with anti-HCMV IgM are suitable assays to diagnose HCMV infection in infants. Both PCR from the blood and HCMV pp65 antigenaemia lack sensitivity in infants. Salivary PCR combines convenience with high sensitivity and can substitute PCR from urine, especially in the outpatient and field settings. To the best of our knowledge, this is the first study from India to evaluate salivary PCR for the diagnosis of congenital HCMV infection.