Molecular Assay Compared to Urinary Culture for Congenital Infection

A real-time polymerase chain reaction (rt-PCR) assay has been evaluated to diagnose Cytomegalovirus (CMV) infection in the urine of neonates.

The real-time CMV PCR was compared with shell vial culture of neonatal urine, which is referred to as the gold standard in the diagnosis of congenital CMV infection.

A team of microbiologists at the Leiden University Medical Center (The Netherlands) analyzed a series of 340 neonatal urines received for congenital CMV diagnostics and routinely assessed with shell vial CMV culture, was retrospectively tested by real-time CMV PCR. All 25 CMV culture positive samples and a large random selection of 315 CMV culture negative urine samples dating from 2001 to 2011 were included in the analysis, irrespective of clinical characteristics of the newborns.

DNA extraction was performed on the MagnaPure LC station using the Total Nucleic Acid Isolation Kit – High Performance Kit Roche Diagnostics, (Almere, The Netherlands) and the PCR was carried out using a CFX96 TM real-time PCR detection system (BioRad; Veenendaal, The Netherlands). The proportion of newborns found to be congenitally infected by real-time CMV PCR was 8.2% (28/340), and 7.4% (25/340) by rapid culture. When considering rapid culture as reference, real-time PCR was highly sensitive (100%), whereas sensitivity of rapid culture was 89.3% when considering real-time PCR as reference.

The authors concluded that supported by analytical and clinical data on CMV DNA detection in neonatal urine, their results suggest enhanced sensitivity of recent PCR techniques when compared to viral culture. There is considerable rationale to favor real-time CMV PCR as a gold standard in the diagnosis of congenital CMV infection. A large-scale study combining both laboratory and clinical data is required to determine the exact time frame for sampling of neonatal urine when using real-time PCR. The study was published in the February 2012 issue of the Journal of Clinical Virology.

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Leiden University Medical Center
Roche Diagnostics
BioRad