Objective: This study was undertaken to evaluate the discriminatory power of the peripheral white blood cell (WBC) count to identify bacterial infections in a cohort of febrile neonates ((28 days of age) presenting to an emergency department. Methods: Retrospective medical record review using descriptive statistics and a receiver operating characteristic (ROC) curve. Neonates who presented to a tertiary care paediatric emergency department between 1 January 1999 and 22 August 2002, had a temperature >38˚C, underwent lumbar puncture, and had a WBC count obtained were included. They were divided according to microbiological and radiographic findings into four groups: bacterial infections, viral infections, pneumonia, and negative sepsis evaluations. Results: A total of 69 febrile neonates met the inclusion criteria. The number of neonates in each group was as follows: 8 with bacterial infections, 10 with viral infections, 3 with pneumonias, and 48 with negative sepsis evaluations. There was substantial overlap in WBC counts among the groups. The area under the ROC curve was 0.7231 (95% CI 0.5665 to 0.8797). Conclusion: In a cohort of febrile neonates evaluated in the emergency department, the WBC count had modest discriminatory power in identifying neonates with bacterial infections and demonstrated substantial overlap among groups. The present data suggest against the use of any WBC count threshold to identify bacterial infections in febrile neonates presenting to the emergency department.

Objective: Our objective was to describe clinically significant infections in a cohort of afebrile neonates who underwent an emergency department (ED) septic workup because of the history of a measured fever at home. Methods: Retrospective medical record review of all infants ≤28 days of age who presented to our tertiary care pediatric ED between Jan. 1, 1999, and Aug. 22, 2002, underwent lumbar puncture in the ED, had a reported temperature at home of ≥38°C, and an ED triage temperature of <38°C. Laboratory and radiographic results were tabulated. Results: During the study period, 206 neonates underwent lumbar puncture in our ED. Of these, 108 were excluded because their home temperature was not documented, and 71 were excluded because they were still febrile on presentation to the ED. The study group consisted of the remaining 27 subjects, 4 of whom had received acetaminophen prior to ED arrival. Infections were confirmed in 10 (37%) subjects (3 urinary tract infections, 2 aseptic meningitis, 1 enterovirus meningitis, 1 respiratory syncytial virus bronchiolitis, 1 rotavirus enteritis and 2 pneumonias). Conclusions: Clinically important infections are not uncommon among afebrile neonates undergoing ED septic workup because of a measured fever at home. Some diagnostic testing is warranted in this group, although the clinical utility and indications for specific test modalities remain unclear. RÉSUMÉObjectif : Notre objectif était de décrire les infections cliniquement significatives au sein d'une cohorte de nouveau-nés afébriles ayant subi un bilan septique au département d'urgence (DU) en raison d'antécédents de fièvre mesurée à la maison. Méthodes : Une revue rétrospective fut effectuée des dossiers médicaux de tous les nouveau-nés ≤ 28 jours reçus au DU de notre hôpital pédiatrique de soins tertiaires entre le 1 er janvier 1999 et le 22 août 2002 et qui subirent une ponction lombaire au DU, avaient une fièvre de ≥ 38°C à la maison et une température de triage au DU < 38°C. Les résultats des radiographies et de laboratoire furent totalisés. Résultats : Au cours de la période à l'étude, 206 nouveau-nés subirent une ponction lombaire à notre DU. Parmi ceux-ci, 108 furent exclus parce que leur température à la maison n'avait pas été notée et 71 furent exclus parce qu'ils étaient encore fébriles au DU. Le groupe à l'étude se composait de 27 sujets, dont quatre avaient reçu de l'acétaminophène avant leur arrivée au DU. Des in-

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