Neonatal sepsis may be categorized as early or late onset. Eighty-five percent of newborns with early-onset infection present within 24 hours, 5% present at 24-48 hours, and a smaller percentage of patients present within 48-72 hours. Onset is most rapid in premature neonates. Early onset sepsis syndrome is associated with acquisition of microorganisms from the mother. Transplacental infection or an ascending infection from the cervix may be caused by organisms that colonize in the mother's genitourinary tract, with acquisition of the microbe by passage through a colonized birth canal at delivery. The microorganisms most commonly associated with early-onset infection include group B Streptococcus (GBS), Escherichia coli , coagulase-negative Staphylococcus, Haemophilus influenzae , and Listeria monocytogenes.
Trends in the epidemiology of early onset sepsis show a decreasing incidence of GBS sepsis.[2 ]This article primarily focuses on bacterial infection and sepsis. Please see relevant eMedicine chapters for discussion of congenital infection, fungal infection, and viral infection of the newborn.
Trends in the epidemiology of early onset sepsis show a decreasing incidence of GBS sepsis.[2 ]This article primarily focuses on bacterial infection and sepsis. Please see relevant eMedicine chapters for discussion of congenital infection, fungal infection, and viral infection of the newborn.
Late-onset sepsis syndrome occurs at 4-90 days of life and is acquired from the caregiving environment. Organisms that have been implicated in causing late-onset sepsis syndrome include coagulase-negative staphylococci, Staphylococcus aureus , E coli, Klebsiella, Pseudomonas, Enterobacter, Candida, GBS, Serratia, Acinetobacter, and anaerobes. Trends in late-onset sepsis show an increase in coagulase-negativeStreptococcal sepsis; most of these isolates are susceptible to first-generation cephalosporins.[2 ]The infant's skin, respiratory tract, conjunctivae, GI tract, and umbilicus may become colonized from the environment, leading to the possibility of late-onset sepsis from invasive microorganisms. Vectors for such colonization may include vascular or urinary catheters, other indwelling lines, or contact from caregivers with bacterial colonization.
Pneumonia is more common in early onset sepsis, whereas meningitis and bacteremia are more common in late-onset sepsis. Premature and ill infants have an increased susceptibility to sepsis and subtle nonspecific initial presentations; therefore, they require much vigilance so that sepsis can be effectively identified and treated.
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