Electron microscopy in the routine screening of newborns with congenital cytomegalovirus infection

The pseudoreplica method of electron microscopy (EM) was evaluated as a rapid screening technique for the detection of cytomegaloviruria in 3056 neonates in a predominantly lower socioeconomic population. Virus isolation methods detected 49 (1.6%) CMV-positive individuals. When pools of three to five urines were tested, 26 (54%) of the culture-positive neonates were identified by EM; however, testing of individual urines increased EM detection to 33 (67%). Almost all of these urines, as well as urine or oral specimens obtained on follow-up visits, which had infectivity titers greater than or equal to 10(4)/ml were EM-positive, whereas only half of the specimens with titers less than 10(4)/ml were EM-positive. All the symptomatic neonates were detected by EM, suggesting that electron microscopy would be most valuable as a diagnostic aid in this group of CMV-infected neonates.