Chapter 76 Systemic Bacterial Infection
PATHOPHYSIOLOGY
Infants and toddlers with a systemic bacterial infection often present with few, nonspecific signs of illness. The younger the child, the more difficult it is to recognize a bacterial infection by history. If a systemic bacterial infection is suspected, urgent investigation is performed, which is called a septic workup, and immediate intravenous antibiotic therapy is administered to prevent the illness from becoming life-threatening.
The risk of a systemic bacterial illness is generally believed to be higher in febrile infants under 3 months of age than in older febrile infants. The types of systemic bacterial infections are septicemia, occult bacteremia, and meningitis. Septicemia is the presence of microorganisms in the blood, with a localized or systemic diseaase in an ill-appearing child. Occult bacteremia is a bacteremia with a benign appearance and no other apparent source of serious infection. Factors increasing the risk of bacteremia are young age, premature birth, previous serious illness, chronic illness, ill appearance, fever, elevated white blood cell (WBC) count, and elevated absolute neutrophil count. Meningitis is an acute inflammation of the meninges and cerebrospinal fluid from a bacterial pathogen.
The most common serious bacterial infections in children older than 3 months of age are meningitis, bacteremia, urinary tract infection, pneumonia, soft-tissue infections, and enteric infections. The occurrence of a child having an acute episode of fever with a systemic illness is greater in children older than 3 months of age. Conversely, owing to an infant’s immature immune system, infants younger than 1 month of age rarely become febrile, and more often hypothermia is seen with systemic bacterial infections. However, most febrile young children have self-limited viral infections.
INCIDENCE
1. In febrile infants under 3 months of age with a rectal temperature of 100.4° F (38.0° C) or higher, the prevalence of serious bacterial illness is approximately 8% to 10%.
2. The risk of occult bacteremia in children 3 to 36 months of age with fever but without localizing signs is approximately 2% to 10%.
3. Group B Streptococcus (GBS) now accounts for most bacterial infections in infants younger than 3 months of age.
4. Streptococcus pneumoniae is the most prevalent bacterial infection in healthy children older than 3 months of age.
5. Fever in children from 3 to 36 months of age is seen more often between November and March.
6. Approximately 10% of children with bacteremia will develop a systemic bacterial infection.
7. Hearing impairment is the most common sequela from meningitis.
