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Capillary white blood cell (WBC) counts can help identify infants with unexplained fever who may have bacteremia. Specific WBC criteria effectively distinguish high-risk infants needing blood cultures from those likely to recover without antibiotics.
Area of Science:
- Pediatric Infectious Diseases
- Clinical Pathology
- Hematology
Background:
- Unexplained febrile illness in infants and toddlers poses diagnostic challenges.
- Distinguishing bacteremia is crucial for timely antibiotic intervention and preventing complications.
- Office-based diagnostic tools are needed to guide further testing like blood cultures.
Purpose of the Study:
- To evaluate the utility of capillary white blood cell (WBC) count and differential in identifying bacteremia in febrile infants and toddlers.
- To determine specific WBC criteria predictive of bacteremia in this age group.
- To assess the ability of these criteria to differentiate infants who require blood cultures from those who do not.
Main Methods:
- Retrospective analysis of 146 infants (3-24 months) with unexplained febrile illness.
- Capillary WBC count and differential performed in office practice.
- Four criteria evaluated: WBC count ≥15,000/cu mm, segmented neutrophils ≥10,000/cu mm, band cells ≥500/cu mm, and total polymorphonuclear leukocytes ≥10,500/cu mm.
Main Results:
- Bacteremia was confirmed in 8 out of 146 infants.
- Seven of the 8 bacteremic infants met three or four of the defined WBC criteria.
- Only 10 (7.2%) of the 138 non-bacteremic infants met the same criteria (P < .001).
Conclusions:
- Capillary WBC count and differential are valuable tools for risk stratification in febrile infants.
- The established WBC criteria help identify infants with a higher likelihood of bacteremia.
- This approach can guide decisions regarding blood cultures and early bacteriologic diagnosis, potentially avoiding unnecessary antibiotic treatment in low-risk infants.
Abstract:
The capillary white blood cell count and differential, a test easily done in office practice, was used in unexplained febrile illness of infants and toddlers to help distinguish those babies most likely to have bacteremia who would benefit from blood culture and early bacteriologic diagnosis. Four criteria were used as indicators suggestive of bacterial infection: white blood cell count greater than or equal to 15,000/cu mm, total segmented neutrophils greater than or equal to 10,000/cu mm, total band cells greater than or equal to 500/cu mm, and total polymorphonuclear leukocytes (segmented neutrophils plus band cells) greater than or equal to 10,500/cu mm. These measurements were found helpful in separating a small group of bacteremic babies at high risk of complications from a large group of babies who recovered without antibiotic treatment and without complications. There were 146 febrile illnesses recorded in babies 3 to 24 months of age; bacteremia was proven in eight of these. Three or four blood cell count criteria were fulfilled in seven of the eight bacteremic babies and in only ten (7.2%) of the remaining 138 febrile illnesses (P < .001 by chi 2 test).