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.

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Viperidae snakes containing various venomous proteins also have several anti-toxic proteins in their sera. However, the physiological function of serum protein has been elucidated incompletely. Small serum protein (SSP)-1 is a major component of the SSPs isolated from the serum of a Japanese viper, the habu snake (Trimeresurus flavoviridis). It exists in the blood as a binary complex with habu serum factor (HSF), a snake venom metalloproteinase inhibitor. Affinity chromatography of the venom on an SSP-1-immobilized column identified HV1, an apoptosis-inducing metalloproteinase, as the target protein of SSP-1. Biacore measurements revealed that SSP-1 was bound to HV1 with a dissociation constant of 8.2 × 10⁻⁸ M. However, SSP-1 did not inhibit the peptidase activity of HV1. Although HSF alone showed no inhibitory activity or binding affinity to HV1, the SSP-1-HSF binary complex bound to HV1 formed a ternary complex that non-competitively inhibited the peptidase activity of HV1 with a inhibition constant of 5.1 ± 1.3 × 10⁻⁹ M. The SSP-1-HSF complex also effectively suppressed the apoptosis of vascular endothelial cells and caspase 3 activation induced by HV1. Thus, SSP-1 is a unique protein that non-covalently attaches to HV1 and changes its susceptibility to HSF.

Anchoring bias is one of the most common diagnostic biases that may lead to closed-minded thinking and could result in unnecessary tests, inappropriate patient management and even misdiagnosis. A 4-year-old boy was brought to the emergency department because of shaking chills. On the basis of bilateral swollen preauricular areas, high level of serum amylase and the prevalence of mumps, he initially received a diagnosis of mumps in spite of the shaking chills. However, blood culture turned out to be positive for two different kinds of bacteria. The patient finally received a diagnosis of polymicrobial bacteraemia resulting from suppurative appendicitis. We must consider and rule out bacteraemia in the differential diagnosis for patients who present with shaking chills, even in the presence of symptoms or information consistent with a more common viral infection such as mumps. In addition, intra-abdominal infection should be ruled out in the presence of polymicrobial enterobacteriaceae bacteraemia.

Background Febrile children 3–36 months old, who had a body temperature >39°C and white blood cell (WBC) count >15 000/mm3 were known to be at risk for occult pneumococcal bacteremia (OPB) in the pre‐pneumococcal conjugate vaccine (PCV) era. The positive predictive value of these criteria, however, decreased dramatically after the introduction of PCV, indicating a need for alternative criteria. A high rate of febrile seizures has been noted in children with OPB, suggesting that screening may still be practical in this population. We performed a retrospective analysis to evaluate factors that predict OPB in patients visiting the emergency department (ED) with febrile seizures. Methods Children 3–36 months old who visited the ED for febrile seizures and had blood cultures taken were included. Patients with underlying diseases were excluded from analysis. We performed statistical analyses comparing patient demographics according to the presence or absence of OPB. Results One thousand and eighty‐two patients visited the ED with febrile seizure, and blood cultures were taken in 397, of whom 87% had received more than three doses of PCV. Of the nine patients with OPB, eight (89%) met the risk criteria. In contrast, only 12% (48/388) of those without OPB met the criteria. In this population, those who fulfilled the risk criteria were more likely to have OPB than those who did not (14.3% vs 0.3%; likelihood ratio, 7.17). Conclusions High WBC count and fever may effectively predict OPB in pediatric patients with febrile seizure in the post‐PCV era.