High Rate of Febrile Seizures in Japanese Children With Occult Bacteremia.

Objectives: Fever of 39°C or higher and a white blood cell (WBC) count of 15,000/μL or greater are known predictors of occult bacteremia (OB). However, because of a decreasing prevalence of OB, WBC counts have become poor predictors of OB in populations of routinely immunized children. Thus, we aim to evaluate the clinical characteristics of OB in Japanese children and identify potential risk factors for OB.

Methods: We conducted an observational study of children aged 3 to 36 months old with positive blood cultures for Streptococcus pneumoniae or Haemophilus influenzae at an emergency department in a tertiary care children's hospital between April 2002 and December 2015. Patients with significant underlying diseases, a proven source of infection, or toxic appearance, were excluded.

Results: Positive blood cultures were recorded in 231 patients; of these, 110 were included in the study (S. pneumoniae, n = 102; H. influenzae, n = 8). Median age was 16 (3-34) months. Patients had a high median body temperature of 39.2 (interquartile range, 38.6-39.9) °C and median WBC of 21,120 (interquartile range, 16,408-24,242)/μL. A high rate of febrile seizures (58 patients, 53%) was observed, with complex febrile seizures accounting for 43% of the episodes. Frequency of febrile seizures was positively associated with age (P = 0.001).

Conclusions: Our study revealed a high rate of children presenting with febrile seizures, especially complex seizures, among children with OB in Japan. A further study is necessary to evaluate the role of febrile seizures as a predictor for OB.