Neonatal Sepsis

Invasive bacterial infection which occurs in the first 4 week of life. Bacterial infection are the primary cause in 10% to 20% of neonatal deaths., low weight infants develop serious bacterial infection 5 times more often than normal weight babies. An infant may be predisposed to neonatal sepsis by obstetric complications, such as premature rupture of the membranes, toxemia, precipitous delivery, maternal infection. When the infants history includes a perinatal complication, neonatal sepsis is usually diagnosed in the first 5 days of life. By contrast, sepsis develops at about 2 weeks of age in infant without a history of predisposing factors, this group includes those who acquire nosocomial infections.

The clustering of neonatal bacterial infections in the perinatal period suggests that pathogens usually are acquired during labor and delivery. Hematogenous and transplacental dissemination of maternal infection occurs in the transmission viral, protozoal and treponemal agents. A few uncommon bacterial pathogens reach the fetus transplacentally, but most are acquired by the ascending route, in utero or as the fetus passes through the birth canal. Organisms may also invade the fetal circulation by contamination of superficial chorionic vessels or, more commonly, by fetal aspiration or swallowing of contaminated amniotic fluid.

The Low weight birth (LBW) infants has a lower level of IgG than does the normal infant, the level decreases in direct proportion to the degree of immaturity. IgM provides activity against gram-negative enteric bacilli, but does not cross the placenta. The consequent immunoglobulin deficiency may play a role in diminishing the amount of heat-stable opsonin (antibody) available to the neonate. Gestational age related defects in opsonization appear to be largely responsible for rendering the LBW infant at particular risk to bacterial infection. Most of the opsonizing power of newborn serum resides in the heat-labile fraction.

Because the newborn can respond to perinatal insults in only a few ways, the early signs of neonatal sepsis are nonspesific and may be subtle, such as diminished spontaneous activity or less vigorous sucking. Hyper or hypothermia, respiratory distress, neurologic signs, jaundice, vomiting, diarrhea, and abdominal distention all occur with varying frequency, but none of these signs is specific for sepsis. Specific signs that characterize of an affected organ may pinpoint the source of metastatic site. Routine examination of the ears, preferably with pneumatic otoscopy, identifies otitis media. Because infection prevents obliteration of the umbilical vessels, umbilical erythema, discharge or bleeding suggests omphalitis.