Abstract
OBJECTIVE: To examine whether preterm very low birth weight (VLBW) infants have an increased risk of late-onset sepsis (LOS) following early-onset sepsis (EOS). STUDY DESIGN: Retrospective analysis of VLBW infants (401-1500 g) born September 1998 through December 2009 who survived >72 hours and were cared for within the National Institute of Child Health and Human Development Neonatal Research Network. Sepsis was defined by growth of bacteria or fungi in a blood culture obtained ≤ 72 hours of birth (EOS) or >72 hours (LOS) and antimicrobial therapy for ≥ 5 days or death <5 days while receiving therapy. Regression models were used to assess risk of death or LOS by 120 days and LOS by 120 days among survivors to discharge or 120 days, adjusting for gestational age and other covariates. RESULTS: Of 34,396 infants studied, 504 (1.5%) had EOS. After adjustment, risk of death or LOS by 120 days did not differ overall for infants with EOS compared with those without EOS [risk ratio (RR): 0.99 (0.89-1.09)] but was reduced in infants born at <25 weeks gestation [RR: 0.87 (0.76-0.99), P = .048]. Among survivors, no difference in LOS risk was found overall for infants with versus without EOS [RR: 0.88 (0.75-1.02)], but LOS risk was reduced in infants with birth weight 401-750 g who had EOS [RR: 0.80 (0.64-0.99), P = .047]. CONCLUSIONS: Risk of LOS after EOS was not increased in VLBW infants. Surprisingly, risk of LOS following EOS appeared to be reduced in the smallest, most premature infants, underscoring the need for age-specific analyses of immune function.