Which of the following does not establish a diagnosis of active congenital CMV infection in a neonate?

Congenital CMV disease is confirmed by an IgM assay from fetal blood. CMV IgG antibodies indicative of past infection. The most sensitive way to detect CMV in blood or other fluids may be by amplifying CMV DNA by polymerase chain reaction (PCR). The PCR assays are designed to detect replicating virus, not latent viral genomes. Blood and urine are most commonly tested. Isolation of CMV or detection of its antigens or DNA in appropriate clinical specimens is the preferred approach for the diagnosis. The clinical specimens commonly used are urine, saliva, blood. The hallmark of CMV infection on histologic examination is a large cell containing a large basophilic intranuclear "owl's eye" and intracytoplasmic inclusion bodies. Ref: Brooks G.F. (2013). Chapter 33. Herpesviruses. In G.F. Brooks (Ed), Jawetz, Melnick, & Adelberg's Medical Microbiology, 26e.