OCCULT BACTEREMIA FROM A PEDIATRIC EMERGENCY DEPARTMENT: CURRENT PREVALENCE, TIME TO DETECTION, AND OUTCOME.

Alpern ER, et al. Pediatrics 2000 Sep;106(3):505-11.

OBJECTIVE: To evaluate selected characteristics of occult bacteremia in the post-Haemophilus influenzae type b (HIB) vaccine era.

METHODS: A retrospective cohort study was performed involving 5901 children 2 to 24 months old with fever >/=39.0 degrees C evaluated with a blood culture at an urban tertiary care children's hospital emergency department (ED) between February 1993 and June 1996. Patients were excluded if immune-suppressed, diagnosed with a focal infection, evaluated by lumbar puncture, or admitted to the hospital during initial evaluation. Prevalence of occult bacteremia, distribution of current pathogenic organisms, and time to positive culture in a continuously monitored system were determined. All patients with cultures positive for pathogenic bacteria were reevaluated and serious adverse outcomes were documented.

RESULTS: The prevalence of occult bacteremia was 1.9% (95% confidence interval: 1.5%-2.3%). Streptococcus pneumoniae accounted for 82.9% of all pathogens and H influenzae was not a causative organism in this cohort. The mean time to positive culture was significantly shorter for pathogens compared with contaminants (14.9 hours vs 31.1 hours). A culture that was positive in </=18 hours was 13.0 (6.3-26. 6) times more likely to contain a pathogen than a contaminant. The average time from positive culture notification to reevaluation in the ED was 10.6 hours and over half of the patients recalled to the ED for positive cultures were admitted to the hospital. Of patients with occult pneumococcal bacteremia, 95.7% had resolution of their bacteremia without the use of parenteral antibiotics. Two patients had serious adverse outcomes. The rate of meningitis or death was. 03% (.004%-.12%). The contamination rate of blood cultures was 2.1% (1.7%-2.5%). Most (85%) of these patients were reevaluated in the ED and more than one third were admitted to the hospital before full identification of the organism.

CONCLUSIONS: Prevalence of occult bacteremia in the post-HIB vaccine era is lower than previously reported. S pneumoniae is the most common causative organism and resolves without parenteral antibiotics in the vast majority of cases. Continuously monitoring blood culture systems allow for early identification and can aid in differentiating contaminated from true pathogenic cultures by time to positive culture. Serious adverse outcome is an uncommon result of occult bacteremia. Updated epidemiology and microbiologic technology may impact the evaluation and treatment of children at risk for occult bacteremia.

RISK OF SERIOUS BACTERIAL INFECTION IN CHILDREN WITH FEVER WITHOUT A SOURCE IN THE POST-HAEMOPHILUS INFLUENZAE ERA WHEN ANTIBIOTICS ARE RESERVED FOR CULTURE-PROVEN BACTEREMIA.

Bandyopadhyay S, et al. Arch Pediatr Adolesc Med 2002 May;156(5):512-7.

OBJECTIVE: To determine the rate of serious bacterial infection in children aged 2 to 36 months with fever without a source in the post-Haemophilus influenzae era, when antibiotic therapy is reserved until blood culture results turn positive.

DESIGN AND SETTING: Retrospective review of emergency department, urgent care center, and hospital medical records from an urban children's hospital.

PARTICIPANTS: Eligible participants were identified from hospital medical record and microbiology laboratory databases. Immunocompetent individuals aged 2 to 36 months with fever without a source were eligible for enrollment. Exclusion criteria were temperature less than 39.0 degrees C, identifiable focus of infection, current or recent antibiotic use, and hospital admission.

INTERVENTIONS AND OUTCOME MEASURES: Enrolled participants were assigned to group 1 (blood culture obtained) or group 2 (no blood culture) and did not receive empiric antibiotic treatment in the emergency department, in the urgent care center, or for home use. Demographic and outcome data were collected on all enrolled patients. RESULTS: During the study, 9241 febrile children were identified; 2641 (29%) met the enrollment criteria. Blood cultures (group 1) were performed on 1202 patients (46%), and 37 (3%) had culture-proven occult bacteremia (95% confidence interval, 2.2%-4.2%). Streptococcus pneumoniae was the most prevalent organism (84%). The mean +/- SD time for reporting a positive blood culture finding was 17.5 +/- 8.5 hours. Two patients (0.08%; 95% confidence interval, 0.009%-0.27%) developed serious bacterial infection, and both recovered completely.

CONCLUSION: Reserving antibiotic therapy for culture-proven occult bacteremia was not associated with increased risk of developing serious bacterial infection compared with previously published data.

COMMENTS: For a good article on approaching the pediatric patient with fever, see Evaluation Styles For Well-Appearing Febrile Children: Are You A "Risk-Minimizer" Or A "Test-Minimizer"? by Green, SM, et al, Ann Emerg Med 33(2):211, February 1999.