What is the emergent workup for children 2-24 months old with fever?

Updated: Jul 23, 2019
  • Author: Hina Z Ghory, MD; Chief Editor: Russell W Steele, MD  more...
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In children who have been immunized against pneumococcal disease, the routine use of CBC and blood culture are no longer recommended. [53, 54, 55] If a CBC is obtained, interpretation of the total WBC remains controversial. Distinguishing between a high total WBC count versus a very high WBC count may leave the physicians with even more questions about the relevance of this laboratory result. [53, 56, 57]

The rates of bacteremia and invasive pneumococcal disease have dramatically declined since the licensing of the 7-valent pneumococcal vaccine (PCV7) vaccine in 2000. [13, 58, 59, 60, 61, 62, 63] This vaccine protects against the 7 pneumococcal serotypes that cause 85% of invasive pneumococcal disease in children, including nearly all of the serotypes that are highly penicillin resistant.

Prior to routine use of the pneumococcal vaccine, occult bacteremia occurred with an incidence of 3-5% in children younger than 24 months with fever. Studies in the 1980s-1990s showed the rate of occult bacteremia was as high as 5%. In the 21st century, studies show a decline in the rates to as low as 0.5-1%. [64] This change is most likely due to the increasing rates of pneumococcal vaccinations. [65]

Before widespread PCV7 use, approximately 60-70% of all cases of occult bacteremia were caused by Streptococcus pneumoniae. S pneumoniae is the most prevalent and certainly the most significant cause of morbidity and mortality related to occult bacteremia.

In 2010, the US Food and Drug Administration (FDA) licensed a 13-valent pneumococcal vaccine (PCV13), which includes protection against additional strains of pneumococcus, including serotype 19A. This PCV13 vaccination will supplant the PCV7 vaccination, presumptively causing a further decline in invasive pneumococcal disease. [66, 67] The routine use of pneumococcal vaccine has essentially made rates of occult bacteremia a classic historical discussion. [63]

Before routine use of the HIB vaccine, HIB accounted for 20% of occult illness, but this cause also decreased in frequency after the vaccination became routine in the 1990s. [68, 69]

An increase in the total band count or erythrocyte sedimentation rate (ESR) is not more predictive of occult pneumococcal bacteremia than an elevated WBC count alone. Before the routine use of the pneumococcal vaccine, a WBC count above 15,000/mm3 had been reported to be 70% sensitive for predicting occult bacteremia from pneumococcus. [70]

Children in this age group who present with a higher temperature (>102.9°F [>39.4°C]) may be at risk for occult bacteremia, especially if they are underimmunized or immunosuppressed. By definition, occult means that the patient exhibits no other signs or symptoms suggesting the etiology of the temperature elevation.

Other less common etiologic agents are Neisseria meningitides and (especially in patients with sickle cell disease) Salmonella species. [58] Herpes and community-acquired methicillin-resistant Streptococcus aureus (MRSA) are now emerging as more common pathogens in neonates. [71, 72, 73, 74, 75, 76, 77, 78]

Children younger than 24 months presenting with the clinical syndrome of bronchiolitis are at a lower risk of bacteremia and UTIs. Therefore, routine urine and blood culturing in previously healthy children presenting with fever and bronchiolitis is usually not indicated; extreme fever or ill appearance may be indications to obtain a blood culture. Testing of the nasal secretions for a viral etiology such as respiratory syncytial viral (RSV) or influenza A/B may be helpful. [79]

Rates of UTI may be lower in patients with bronchiolitis than those without any fever source. [80]

Viral infections are the most common cause of fever in young children aged 2-24 months. Well-appearing children with unremarkable histories and physical examinations may be discharged home without laboratory testing or presumptive use of antibiotics. An LP should be considered for those who are irritable, lethargic, inconsolable, or toxic appearing.

During summer months, children with fever and no other signs may have an enterovirus infection. Some studies report the incidence as high as 50% in febrile children in the ED. Enteroviral infection is a clinical diagnosis for the emergency physician. No specific laboratory testing is indicated.

Diarrhea most commonly has a viral etiology in this age group. The presence of diarrhea with blood or mucus or recent use of antibiotics may be indications for ordering stool cultures to assess for a bacterial etiology.

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