Patient and prescriber factors and the prolongation of antibiotics after birth in infants less than 29 weeks.

Objective: The objective of this study is to delineate whether patient-related or prescriber-related factors account for the prolongation of antibiotic therapy beyond 48h in premature infants whose initial blood cultures are negative.Methods: Retrospective review of infants born <29weeks born between January 2011 and December 2012. Infants who had positive blood cultures or who died in the first 48h were excluded from analysis. Antibiotic courses were categorized as prolonged if antibiotics were continued for greater than 48h and not prolonged if antibiotics were stopped by 48h. Neonatologists were classified as high prescribers if they prolonged antibiotics for more than the median rate for the overall group.Results: Seventeen of 59 (29%) infants had empiric antibiotics continued for greater than 48h despite negative blood cultures. Both patient-related factors and the neonatologist at 48h of life were significantly associated with prolongation of antibiotics. Patient-related factors associated with prolongation of empiric antibiotics were positive maternal Group B streptococcus (GBS) status (5/17 versus 4/42); p=.054), white blood count >25,000 (7/17 versus 1/42); p<.001), rupture of membranes (ROM) duration (187253h versus 47 +/- 89h; p=.015). Increased number of risk factors was associated with increased likelihood of prolongation. Risk factors for sepsis were similar between high and low prescribing neonatologists with high prescribers prolonging antibiotics with a lower number of risk factors.Conclusions: The decision to prolong empiric antibiotics in culture negative preterm infants is related both to patient and prescriber-related factors.