Biology Reference
In-Depth Information
approximately 2 in 1000 live births. Alarmingly, 7% to 13% of neonates
show symptoms or signs of infection and are evaluated for sepsis.
Infection is a major cause of fatality during the first month of life,
contributing to 13% to 15% of all neonatal deaths. The mortality rate in
neonatal sepsis may be as high as 50% for infants not receiving prompt
treatment.
Neonatal sepsis is categorized as early or late onset. Eighty-five percent
of newborns with early-onset sepsis have symptoms within their first
24 hours of life, with the remaining 15% of cases occurring within 5 to
6 days after birth. Early onset sepsis is connected with an infant's
acquisition of microorganisms from the mother, perhaps at delivery by
passage through a colonized birth canal. The microorganisms most
commonly associated with early onset infection include group B
Streptococcus (GBS), Escherichia coli, Haemophilus influenzae, and Listeria
monocytogenes.
Late-onset sepsis syndrome occurs between 7 and 90 days after birth and
is acquired from the caregiving environment. Organisms implicated in
causing late-onset sepsis include coagulase-negative staphylococci,
Staphylococcus aureus, E. coli, Klebsiella, Pseudomonas, Enterobacter, Candida,
GBS, Serratia, Acinetobacter, and anaerobes. The onset of sepsis is most
rapid and severe in premature infants because their immune system is
generally underdeveloped.
The clinical syndrome of sepsis is brought about by the infant's response
to the insults of the bacterial infection and has been named the systemic
inflammatory response syndrome (SIRS) by the ACCP/SCCM Consensus
Conference Committee (1992). Neonatal sepsis occurs in as many as 25%
of VLBW infants. Neonates who develop late-onset sepsis have a
mortality rate of 17% (more than twice the 7% mortality rate of
noninfected infants), as well as increased morbidity, according to
findings of the National Institute of Child Health & Human
Development Neonatal Research Network (see Bone et al. [1997] and
Stoll et al. [1996]).
Figure 6-1 shows the monitoring equipment typically utilized in the care
of premature infants. Despite the extreme efforts made by NICUs to
eliminate every possibility of bacterial contamination, risk factors for
late-onset sepsis are ever present. Each interventional device is a
potential source of infection and increases the risk of infectious illness
for the newborns. For example, the following medical interventions have
been independently associated with sepsis: intubation, umbilical
catheters, prolonged mechanical ventilation, nutrition via
venous catheters, respiratory distress syndrome, intraventricular
hemorrhage, and nasogastric and tracheal cannulae. As a result,
sepsis is common in neonates, and infected infants spend significantly
more days on the ventilator and an average of 25 more days in the
hospital.
