To determine the prevalence of serious bacterial infection in infants younger than 3 months with fever ≥40°C.
We retrospectively identified all infants younger than 3 months with fever who presented to a pediatric emergency department. The medical records were reviewed. The prevalence of serious bacterial infection (SBI) among those patients with hyperpyrexia was compared with febrile infants with lower fever.
5279 infants younger than 3 months with fever were reviewed. Ninety-eight patients (1.7%) had triage temperature ≥40°C rectally. Median age, temperature, and white blood count for those with hyperpyrexia were 58 days (interquartile range [IQR] 36-78 days), 40.2°C (IQR, 40.0-40.4°C), and 10,800/mm3 (IQR, 7900-14,600/mm3), respectively. Diagnostic studies included blood culture (100%), urine culture (100%), lumbar puncture (100%), chest radiographs (34%), and stool cultures (11%). SBI was found in 38% infants with hyperpyrexia: urinary tract infection was the most common SBI (71%). Among patients with hyperpyrexia, patients with SBI had similar mean white blood cell counts (14,000 vs. 10,200 cells/mm3) and age (54 vs. 53 days) as those with hyperpyrexia but no SBI. The prevalence of SBI among febrile infants with temperatures ≥40.0°C was 38% (95% CI 27-48%) compared with those with fever ≤40°C: 8.8% (95% CI 8.1-9.5%).
Hyperpyrexia is rare among febrile infants younger than 3 months. One-third of infants with temperature ≥40.0°C had SBI. Future management algorithms might include hyperpyrexia as a risk factor for serious infection.