[Plasmatic levels of interleukin-1beta and interleukin-6 in newborn infants with fever].

OBJECTIVE: To study plasma levels of IL-1beta and IL-6 in order to distinguish the presence of bacterial infection in newborn infants with fever. METHODS: A cohort of 117 newborn infants with postnatal age equal to or less than 5 days, with no previous use of antibiotic therapy, and with clinical suspicion of bacterial infection was studied from July 1995 through August 1996. Those with definite criteria for sepsis were considered infected. Fever was defined as axillar temperature > 37.5 degrees C in three independent measurements. The patients were classified in four different groups: Group 1: infected with fever; Group 2: infected without fever; Group 3: not infected with fever; Group 4: not infected without fever. Complete blood count, platelet count, blood or other fluid cultures, and plasmatic levels of IL-1beta and IL-6 were collected before the beginning of antibiotic therapy. RESULTS: Of the 117 newborn infants studied were 66 infected and 51 not infected. Fever was present in 45 (38.46%). The median values of IL-1beta and IL-6 were significantly higher in newborn infants with fever than in those with no fever. There were significant differences between groups 1 and 2, 1 and 4, and 2 and 3 for IL-1beta. There were no significant differences between groups 2 and 4, and 1 and 3 for IL-1beta. Eight (72%) newborn infants with no infection and no fever had environment heating, and 3 had dehydration. There were no differences in median IL-6 levels between groups 1 and 2, and 3 and 4. There were significant differences in the median IL-6 levels between groups 1 and 3, and 1 and 4. CONCLUSIONS: IL- 6 is a marker of early neonatal sepsis. IL-1beta is related to neonatal fever response independently of the presence of bacterial infection.