Study population All neonates who were admitted to the neonatal intensive care unit with a rectal temperature of ≥38°C (documented at the time of medical evaluation) were eligible for the participation in this study. The exclusion criteria were gestational age less than 35 weeks, who refused to participate in the study, chromosome abnormality (e.g., trisomy 21, 18), the presence of a chronic disease, congenital malformations (cyanotic heart disease, meningomyelocele), admission to pediatric surgery, started on antibiotics before admission, and incomplete records. A complete history was obtained from the parents of infants, and a specialist in neonatology carried out a physical examination for localizing the source of the fever in all infants.