Late-onset sepsis (occurring after 3 days of age) is an important problem in very
low birth weight (VLBW) infants. To determine the current incidence of late-onset
sepsis, risk factors for disease, and the impact of late-onset sepsis on subsequent
hospital course, we evaluated a cohort of 7861 VLBW (401 to 1500 gm) neonates admitted
to the 12 National Institute of Child Health and Human Development (NICHD) Neonatal
Research Network centers during a 32-month period (1991 to 1993).
The NICHD Neonatal Research Network maintains a prospectively collected registry of
all VLBW neonates cared for at participating centers. Data from this registry were
analyzed retrospectively.
Of 6911 infants who survived beyond 3 days, 1696 (25%) had one or more episodes of
blood culture-proven sepsis. The vast majority of infection (73%) were caused by gram-positive
organisms, with coagulase-negative staphylococci accounting for 55% of all infections.
Rate of infection was inversely related to birth weight and gestational age. Complications
of prematurity associated with an increased rate of infection included intubation,
respiratory distress syndrome, prolonged ventilation, bronchopulmonary dysplasia,
patent ductus arteriosus, severe intraventricular hemorrhage, and necrotizing enterocolitis.
Among infants with bronchopulmonary dysplasia, those with late-onset sepsis had a
significantly longer duration of mechanical ventilation (45 vs 33 days; p <0.01).
Late-onset sepsis prolonged hospital stay: the mean number of days in the hospital
for VLBW neonates with and without late-onset sepsis was 86 and 61 days, respectively
(p <0.001). Even after adjustment for other complications of prematurity, including
intraventricular hemorrhage, necrotizing enterocolitis, and bronchopulmonary dysplasia,
infants with late-onset sepsis had a significantly longer hospitalization (p <0.001).
Moreover, neonates in whom late-onset sepsis developed were significantly more likely
to die than those who were uninfected (17% vs 7%; p <0.000 1), especially if they
were infected with gram-negative organisms (40%) or fungi (28%). Deaths attributed
to infection increased with increasing chronologic age. Whereas only 4% of deaths
in the first 3 days of life were attributed to infection, 45% of deaths after 2 weeks
were related to infection.
Late-onset sepsis is a frequent and important problem among VLBW preterm infants.
Successful strategies to decrease late-onset sepsis should decrease VLBW mortality
rates, shorten hospital stay, and reduce costs.