Determinants of Initial Antibiotic Duration in Very Low Birth Weight Neonates

Very low birth weight (VLBW) neonates (< 1500 g) are commonly exposed to prolonged antibiotic courses related to concerns for presumed early onset sepsis often with unclear indications. While antibiotics can be life-saving medications, prolonged antibiotic exposure (> 5 days) increases an infant's risk for necrotizing enterocolitis, late onset sepsis, colonization or infection with resistant organisms, and death. The aim of this study is to describe clinical and laboratory factors that influence the length of initial antibiotic courses in VLBW neonates.

Demographics, perinatal factors, and neonatal clinical and laboratory data were compared in a single-center retrospective cohort of VLBW neonates who received ≤ 3 days versus > 5 days of initial antibiotics.

A total of 121 patients were analyzed of which 117 (97%) were started on antibiotics empirically on admission, and 71 (59%) received ≤ 3 days and 50 (41%) received > 5 days of antibiotics. One (0.8%) infant had a positive blood culture (S. oralis). Demographics [gestational age (p < 0.001) and birth weight (p < 0.001)] and neonatal clinical status [Apgar score at 5 min (p = 0.001), CRIB II (p < 0.001), need for inotropes (p = 0.001), and maximum ventilator support (p < 0.001)] were significantly different between the short and prolonged course of antibiotics groups on bivariate analysis. There were no significant differences in perinatal factors or common laboratory markers of sepsis. Maximum ventilator support remained significant on multivariate analysis (p = 0.007).

In the VLBW population, the clinical status of the neonate, as represented by maximum ventilator support in this study, was the most important factor in determining the duration of initial antibiotic treatment. Laboratory values and perinatal risk factors did not significantly influence prescribing patterns.