This summary discusses bacterial sepsis in neonates. Bacterial sepsis in adults and children is addressed separately.

Bacterial sepsis is a major problem in the neonatal intensive care unit: 10% of admitted neonates are treated with antibiotics for presumed sepsis, but a bacterial cause is defined in less than 10% (2/1000 live births) of these treated infants. The highest rates of bacterial sepsis are in preterm infants, particularly those of very low birth weight (less than 1500 g). Also at higher risk are those with decreased respiratory function at birth and those with maternal risk factors such as prolonged (greater than 24 hours) rupture of membranes, bleeding complications, precipitous delivery, toxemia, and maternal infection. Risk is higher in males, Black newborns, and newborns with congenital malformations, particularly of the genitourinary tract.

In developing countries, reported rates of neonatal sepsis are 3-20 times higher than in industrialized countries, presumably due to poor intra- and post-partum infection control practices. Neonatal deaths in developing countries total 1.6 million a year, most from sepsis.

Neonatal sepsis is classified as either early (< 7 days of life) or late (> 7 days) onset. Some define the cutoff at 5 days between early and late onset. Early onset is due to acquisition of organisms from the mother; 85% of cases occur in the first 24 hours after birth and 5% in the next 24 hours. Organisms most often associated are group B Streptococcus, Escherichia coli, Haemophilus influenzae, and Listeria monocytogenes. Other possible agents are Neisseria meningitides and Neisseria gonorrhoeae, Klebsiella, Enterococcus spp, and other streptococci.

Late-onset sepsis is acquired from the environment. Staphylococci are the most common cause (30%-50%), particularly coagulase-negative strains, and are associated with indwelling catheters and lines. The child's skin, umbilicus, respiratory and gastrointestinal tracts, and conjunctivae may become colonized from the environment. Other common organisms are E coli, Klebsiella, Pseudomonas, Enterobacter, Serratia, Acinetobacter, Streptococcus, anaerobes, and Candida. Nosocomial infections in the ICU may be due to multiple-drug resistant organisms. Some viral organisms may present with signs indistinguishable from bacterial sepsis (eg, enterovirus, adenovirus, respiratory syncytial virus, and herpes simplex virus [HSV]).

Complications from sepsis include pneumonia (particularly in early-onset sepsis) and meningitis (more often seen with late-onset sepsis). Other systemic signs of sepsis may include the following: diminished spontaneous activity, decreased sucking vigor, apnea, bradycardia, shock, temperature instability, jaundice, diarrhea, vomiting, and abdominal distention. Site-specific signs of infection include edema, erythema and warmth, coma, seizures, opisthotonos, and a bulging fontanelle.

The overall mortality of early-onset sepsis is 15%-50%, and late-onset sepsis mortality is 10%-20%. The fatality rate is 2-4 times higher in low-birth-weight infants.

Residual neurologic damage occurs in 15%-30% of neonates with septic meningitis.