Postnatally Acquired Cytomegalovirus Infection in Extremely Premature Infants: A Prospective Observational Cohort Study.

AIM: Postnatally acquired cytomegalovirus (pCMV) infection may cause severe disease in extremely preterm infants, but its clinical significance remains uncertain. We investigated the incidence, timing, disease burden, and diagnostic performance of saliva screening. METHOD: In this prospective cohort study, infants born at < 28 weeks of gestation or with a birth weight < 1200 g to CMV-seropositive mothers and fed untreated mothers' own milk underwent weekly saliva and urine CMV polymerase chain reaction testing. Outcomes before discharge and at 2 years corrected age were compared between CMV-positive and CMV-negative infants. RESULTS: Forty-five infants were included, of whom 20 (44%) acquired pCMV. CMV was detected at a median age of 44 days in saliva, 50 days in urine, and 55 days in blood. Two (10%) infected infants developed severe disease requiring antiviral treatment. No significant differences were observed in neonatal morbidity, hospitalisation duration, mortality, or neurodevelopmental outcomes. Saliva PCR demonstrated a sensitivity of 86% and a specificity of 93%. CONCLUSION: pCMV transmission was common in extremely preterm infants receiving mothers' own milk, but clinically significant disease occurred in only a minority of infected infants. Saliva-based screening demonstrated acceptable diagnostic performance and may facilitate early recognition and targeted management of clinically significant pCMV infection.