Saturday, March 25, 2023


Practice Essentials

Bacteremia is the presence of viable bacteria in the circulating blood. Most episodes of occult bacteremia spontaneously resolve, particularly those caused by Streptococcus pneumoniae and Salmonella, and serious sequelae are increasingly uncommon. However, serious bacterial infections occur, including pneumonia, septic arthritis, brain abscesses, osteomyelitis, cellulitis, meningitis, and sepsis, possibly resulting in death.

Signs and symptoms

The significance of the history in a febrile child varies according to the patient’s age. Elements of the history include the following:

Duration of fever (overall, inadequate for clinical identification of occult bacteremia)

History that indicates a specific illness

History that indicates risk for occult bacteremia (eg, Rochester criteria)

History of an underlying medical condition

History of prematurity

History of another reason for an increased temperature (eg, recent vaccinations, overbundling, or environmental exposure to heat involving a young infant)

History of gastroenteritis (suggestive of possible Salmonella bacteremia)


Risk factors for invasive pneumococcal disease

Physical examination may include the following:

Assessment of general appearance

Assessment of vital signs (temperature, pulse, respiratory rate, blood pressure) – The risk of bacteremia has consistently been found to increase with increases in temperature; however, studies have shown a variation in risk at given temperatures based on age

Assessment of response to antipyretics

Inspection for signs of focal infection of the skin, soft tissue, bone, or joints

Inspection for petechiae

Evaluation for acute otitis media or upper respiratory tract infection

Evaluation for pneumonia

Evaluation for recognizable viral infections

See Presentation for more detail.


Laboratory studies that may be helpful in the workup for possible bacteremia include the following:

White blood cell (WBC) count – At present, this is the current established standard screen for bacterial infection, though other screening tests may yield equal or superior results

Absolute neutrophil count (ANC)

Absolute band count (ABC) – This is not recommended as a screen for occult bacteremia but is used in some guidelines as part of the low-risk criteria

Erythrocyte sedimentation rate (ESR) – This is not currently recommended as a screening test for occult bacteremia

C-reactive protein (CRP) level – Although it is not currently an established standard screening test for occult bacteremia, CRP level screening of febrile children in the emergency department is a part of the established protocol at numerous medical centers

Cytokine (eg, interleukin [IL]-1, IL-6, and tumor necrosis factor-a [TNF-a]) levels – These tests have not been thoroughly investigated, have marginal clinical utility, and are of unknown cost-effectiveness; they are not recommended as routine screening laboratory studies for occult bacteremia

Procalcitonin level – This appears to be more sensitive and more specific for bacterial infection than are other laboratory values currently used as screening tests and has good results in illnesses of short duration

Urinalysis and urine culture

Stool studies for children with diarrhea (eg, for Salmonella)

Plasma clearance rate (for meningococcal bacteremia)

Lumbar puncture and cerebrospinal fluid (CSF) analysis

Blood culture

The only imaging study routinely used in infants and children with fever without source (FWS) is chest radiography to evaluate for pneumonia if the child has tachypnea or crackles are heard. Pneumonia should be considered in febrile children with no other source of infection.

See Workup for more detail.


Most infants and young children who are evaluated for occult bacteremia present with a fever. While the child is evaluated to determine a source of the fever, fever reduction with medication is reasonable and is widely accepted.

A combination of age, temperature, and screening laboratory test results is used to determine the risk for serious bacterial infection or occult bacteremia. Subsequent management depends on the level of risk, as follows:

Low-risk children are generally monitored as outpatients

Children who do not fit low-risk criteria are treated with empiric antibiotics either as inpatients or as outpatients

The choice of empiric antibiotic treatment is primarily based on the likely causes of bacteremia for a given patient (which are related to age) and the likelihood of resistance. Regimens include the following:

Neonates younger than 28 days – Ampicillin plus gentamicin; ampicillin plus cefotaxime or ceftriaxone (unless hyperbilirubinemia is present); third-generation cephalosporins are not currently recommended as single-agent therapy in this population

Infants aged 1-3 months – Ampicillin plus gentamicin; ampicillin plus cefotaxime; ceftriaxone; whether Listeria coverage is required in this population is controversial

Infants and children aged 3-36 months – Ceftriaxone (most commonly)

Treatment algorithms that have been employed include the following:

Kuppermann approach (1999)

Baraff approach (2000)

Nigrovic and Malley management guideline (2004)

Further inpatient care may include the following:

Hospitalization – This is recommended for all febrile infants younger than 28 days pending culture results; for infants aged 1-3 months who do not meet low-risk criteria; and for children aged 3-36 months if sepsis is a concern or if outpatient treatment is not feasible

Tailored antibiotic therapy

Further outpatient care may include the following:

Close observation and reevaluation in 24 hours

Antibiotic treatment at follow-up

Monitoring of blood cultures

Reevaluation if the blood cultures become positive with a known pathogen, followed by appropriate treatment

The image below illustrates a treatment approach in febrile infants younger than 3 months.

Application of low-risk criteria and approach for

Application of low-risk criteria and approach for the febrile infant: A reasonable approach for treating febrile infants younger than 3 months who have a temperature of greater than 38°C.

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See Treatment and Medication for more detail.

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