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Children presenting with pathogenic bacteria in a blood culture
(bacteremia) manifest a wide spectrum of clinical
signs and symptoms. The continuum from bacteremia to sepsis, severe
sepsis, and septic shock depends on a complex series of interrelated
factors that include the specific etiology, the inoculum of organisms,
strain variations or virulence factors, extracellular components
or toxin production, the site of infection, the immunologic competence
of the host, and the host response to the infection. Bacteremia
may be occult, a transient phenomenon not associated with a specific focus
of infection, or it may result from the extension of an invasive bacterial
infection originating in the genitourinary, gastrointestinal, upper
or lower respiratory tracts, or skin and soft tissues. Specific
secondary infection (meningitis, osteomyelitis, pyelonephritis,
peritonitis, intra-abdominal abscess, or facial cellulitis) may
also occur and affect management. Recurrent or persistent bacteremia
may result from established infectious foci (endocarditis, abscess, foreign-body
infection).
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Systemic inflammatory response syndrome (SIRS) was defined by
a consensus statement supported by the American College of Chest Physicians
and Society of Critical Care Medicine in 1992.1 Following
that, definitions of sepsis, severe sepsis, and septic shock were developed
for adult patients. In 2005, the International Consensus Conference
on Pediatric Sepsis defined SIRS, sepsis, severe sepsis, and septic
shock in pediatric patients.
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The diagnosis of SIRS in a pediatric patient requires either
abnormal temperature and abnormal leukocyte count, or one of the
former and one of the following: tachypnea or tachycardia (or bradycardia
if younger than 1 year) (Table 223-1). Sepsis
is defined as SIRS plus proven or probable infection. The infectious etiology
may be bacterial, viral, fungal, or rickettsial. Severe sepsis requires
sepsis criteria plus acute respiratory distress syndrome, cardiovascular
dysfunction, or multiorgan dysfunction. Septic shock is sepsis and cardiovascular
dysfunction.2
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Epidemiologic factors that influence the incidence, etiology,
morbidity, and mortality of bacteremia and sepsis in children include
the site of acquisition, immunocompetence of the host, and the presence
or absence of foreign material (central vascular, urinary, peritoneal, or
intraventricular catheters or foreign material following complex
congenital heart disease repair). As of the most recent available
national vital statistics report in 2004, sepsis was the eighth
leading cause of death in the first year of life.3
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Neonatal bacteremia typically results from colonization and subsequent
invasion of the neonate by organisms acquired from the maternal genital
tract. In term newborns, early onset sepsis occurs in approximately
1 to 10 neonates per ...