Recognizing neonatal bacterial sepsis early is one of the most difficult problems that pediatricians encounter. Only 1 in 500 to 1 in 1600 newborns have proven bacterial sepsis. Prematurely born and stressed infants exhibit sepsis more frequently than do unstressed term infants. Therefore, the general pediatrician confronts proven neonatal sepsis uncommonly and needs to be alert to the early signs of sepsis because of the great danger of this potentially treatable condition. Prior to the introduction of antibiotics, mortality from neonatal bacterial sepsis was greater than 90%. Antibiotics and supportive therapy have reduced this mortality to 13% to 50%. There remains much room for improvement. Good outcomes depend on early diagnosis, appropriate treatment, and host factors that still are being explored.
Neonatal sepsis tends to appear as either "early onset" or "late onset" syndromes, but some cases are difficult to classify. Early onset disease is seen in the first few days of life, tends to be fulminant, and is associated more often with maternal or perinatal risk factors, such as maternal fever, prolonged rupture of the membranes, and fetal distress. On the other hand, late onset disease usually occurs after 1 week of age, tends to develop more gradually, and is less likely to be associated with the previously mentioned risk factors.