Detection of Viruria in Cytomegalovirus-infected Infants by Electron Microscopy

Abstract

In evaluating the electron microscopic (EM) method of diagnosing cytomegalovirus inclusion disease, each sample of urine was cultured on primary human embryonic lung cells and examined cytologically for intranuclear inclusions. When cytomegalovirus (CMV) particles were detected by electron microscopy in the urinary sediments of newborns, the sera of the infants usually had increased levels of IgM and significant titers of CMV antibody. The highest CMV complement-fixing titers were found in urines of infants excreting large concentrations of virus. Viral particles observed in urinary sediments were generally disrupted, but the core and attached portion of the outer capsule and envelope were easily distinguishable from cellular debris. Estimated numbers of viral particles in the urine specimens from several patients ranged from 106 to 1010 per ml, while infectious viral titers of urinary CMV from these cases ranged from 10 to 105 per ml. Serologic analysis showed that electron microscopy was a more sensitive method of detecting cytomegalovirus inclusion disease than either cell culture isolation or exfoliative cytology. Four cases were detected by EM, while viral isolation was successful in only two of the cases. Typical intranuclear inclusions were found in cytologic urinary smears in only one of the four cases. The diagnosis of cytomegalovirus inclusion disease by EM requires only four hours, while the times required by cell culture methods may range from four to 70 days, depending upon the amount of virus excreted in the urine. EM appears to be a rapid sensitive method for detecting viruria in cytomegalovirus inclusion disease of the newborn.