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Low Risk of Bacteremia in Children With Febrile Seizures
Samir S. Shah, MD;
Elizabeth R. Alpern, MD;
Lisa Zwerling, MD, MPH;
Jennifer R. Reid, MD;
Karin L. McGowan, PhD;
Louis M. Bell, MD
Arch Pediatr Adolesc Med. 2002;156:469-472.
ABSTRACT
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Objective To evaluate the risk of bacteremia in children with febrile seizures
treated as outpatients.
Methods A retrospective cohort study was performed involving 379 children aged
2 to 24 months presenting to an urban tertiary care children's hospital emergency
department with a febrile seizure between February 1, 1993, and May 31, 1996.
Results The mean patient age was 15.9 months, and 217 (57%) were male. In 40
patients (10.6%), the use of oral antibiotics before initial emergency department
evaluation was reported. Bacteremia occurred in 8 (2.1%) of 379 children studied.
None of the children with bacteremia had received previous antibiotics. The
causative organisms were Streptococcus pneumoniae
in 7 cases and group A Streptococcus in 1 case. There
were 5 contaminated cultures (1.3%). Although 2 of the 8 children with bacteremia
ultimately required admission, there were no serious adverse outcomes. Six
of 7 episodes of S pneumoniae bacteremia were caused
by serotypes included in the pneumococcal conjugate vaccine, which was not
available at the time of this study.
Conclusions Children 2 to 24 months of age with febrile seizures are at similar
risk for occult bacteremia as those with fever alone. Widespread use of the
pneumococcal conjugate vaccine may further decrease the incidence of bacteremia
in this population.
INTRODUCTION
FEBRILE SEIZURES are a common pediatric problem, occurring in 2% to
5% of all children.1 The examination of children
who present to the emergency department (ED) with a febrile seizure is controversial.
Although numerous authors have examined the issue of whether these children
should have lumbar punctures, only a few have examined the role of blood cultures
in the evaluation of such children.2-6
In 1976, Lewin et al2 noted that bacteremia
was present in 4 (6.7%) of 61 children with febrile seizures. These findings
led to their recommendation that a complete blood cell count and blood culture
be performed on all children presenting with febrile seizures. Lewis et al3 identified a specific viral cause in 46 (63.0%) of
73 children with febrile seizures. However, 2 children (2.7%) in their study
had bacteremia associated with significant morbidity: one with Haemophilus influenzae type b meningitis and the other with Escherichia coli endocarditis. In a study by Chamberlain and Gorman,4 5 (4.3%) of 115 children with febrile seizures who
were treated in the outpatient setting had bacteremia. Streptococcus pneumoniae was identified in each case. The repeated
blood culture was negative in all 5 children, and only 3 had been treated
with antibiotics after the original culture had been obtained. In a prospective
study of children between 6 months and 5 years of age with febrile seizures,
McIntyre et al5 found bacteremia in 12 (4.3%)
of 282 children. All 12 children were younger than 2 years, and the organisms
isolated were S pneumoniae (7 cases), H influenzae type b (3 cases), Neisseria meningitidis (1 case), and Salmonella enteritidis (1 case).
These studies evaluated the incidence of bacteremia in children with febrile
seizures in the pre– H influenzae type b vaccine
era and included children beyond the age usually identified as being at risk
for occult bacteremia.
Since the introduction of the H influenzae
type b vaccine, the rates of bacteremia in febrile children have apparently
decreased.7-9 In
the first study of children with febrile seizures since the introduction of
the H influenzae type b vaccine, Teach and Geil6 studied 206 children younger than 6 years. The incidence
of bacteremia was 2.9%. Streptococcus pneumoniae
was identified in each case, and no child had meningitis. These data suggest
that not all children who present to the ED with a febrile seizure require
a blood culture. We performed a retrospective cohort study to determine the
occurrence of bacteremia in well-appearing children presenting with febrile
seizures who were treated in the outpatient setting. This study was limited
to children between 2 and 24 months of age, a population at higher risk for
occult bacteremia.
PATIENTS AND METHODS
STUDY DESIGN AND SETTING
This retrospective cohort study included children 2 to 24 months of
age with a febrile seizure who had blood cultures drawn in the ED of an urban
tertiary care children's hospital between February 1, 1993, and May 31, 1996.
A subset of this cohort was included within a larger study population previously
described.7 During the study period, the ED
saw approximately 54000 children annually.
Standard practice during the study period was to obtain blood cultures
on children 2 to 24 months of age with temperatures of 39.0°C or more
but did not include routine complete blood cell counts. The decision to obtain
blood cultures on children with febrile seizures who did not meet the previous
criteria was made by the examining physician on the basis of clinical examination.
Lumbar puncture was performed on the basis of clinical assessment by the examining
physician and was not part of a standard protocol for children with febrile
seizures within this age range.
Blood cultures were obtained by ED nurses using sterile techniques and
inoculated into pediatric blood culture bottles (Pedi-BacT; Organon Teknika
Corp, Durham, NC). A single bottle containing supplemented brain-heart infusion
broth with 0.02% sodium polyanethol sulfonate was inoculated for each blood
culture ordered. Standard procedure in the ED was to inoculate 0.5 to 1.0
mL. Through a pneumatic tube delivery system, blood cultures were routinely
received in the laboratory within an hour of when they were taken and were
immediately loaded into the blood culture instrument. The microbiology laboratory
used a microbial detection system (BacT/Alert; Organon Teknika Corp) to process
all blood cultures. The system monitored carbon dioxide production within
each bottle every 10 minutes, 24 hours per day. Bottles identified as positive
were immediately removed from the instrument, 24 hours per day, and an aliquot
was taken for gram stain and subculture. The ED was notified immediately of
the positive culture and given information from the gram stain. Bacterial
isolates were identified by conventional procedures. Only information from
the gram stain, however, was available at the time of initial report of positive
culture to the ED. Routine protocol included contacting families of all children
with positive blood cultures for reevaluation.
PARTICIPANTS
Patients were included if they were diagnosed as having a simple or
complex febrile seizure, had a blood culture obtained during the initial ED
evaluation, and were discharged to home after evaluation. Patients were excluded
if during initial ED evaluation they (1) were diagnosed as having a central
nervous system disorder that predisposed them to seizures (eg, meningitis,
static encephalopathy, seizure disorder); (2) were known to have an underlying
condition that predisposed them to bacteremia (eg, sickle cell anemia, oncologic
disease, immunodeficiency, indwelling central catheter); (3) underwent lumbar
puncture; (4) had an illness requiring hospitalization; or (5) died during
initial ED evaluation.
MEASURED OUTCOMES AND PROTOCOL
Bacteremia was defined as a blood culture obtained from a patient at
initial ED presentation that was positive for pathogenic bacteria. Bacteria
that were considered pathogenic included the following: S pneumoniae, Staphylococcus aureus, group
A Streptococcus, Enterococcus species, N meningitidis, Enterobacteriaceae, Salmonella
species, Moraxella catarrhalis, Pseudomonas species, H influenzae, Campylobacter species, and Escherichia coli.
Bacteria that were considered contaminants included coagulase-negative Staphylococcus species,  -hemolytic Streptococcus, Micrococcus species, Clostridium species, Corynebacterium species, and Neisseria species other than N meningitidis or Neisseria gonorrhoeae. Time to positive culture was measured in hours and tenths of hours.
Serious adverse outcome was defined as meningitis or death within 2 weeks
of the date that the blood culture was obtained.
All children with blood cultures obtained during the study months were
identified by means of microbiology laboratory data from the microbial detection
system. These data indicated the patient's name, medical record number, and
final result of blood culture. Additional information collected included age
of the patient, date of blood culture collection, disposition (admission or
discharge), and time in hours to positive culture and identification of bacteria.
The medical records of patients were abstracted for medical history, previous
antibiotic use, ED discharge diagnoses, maximum fever documented in the ED,
and antibiotic treatment or prescription. Charts of patients with blood cultures
positive for pathogenic or contaminant bacteria were abstracted for additional
data, including follow-up visit site, date, and time; diagnosis and disposition
at follow-up visit; maximum temperature documented at follow-up visit; results
of repeated blood culture, complete blood cell count, chest x-ray, spinal
fluid assessment, urinalysis, and urine culture; and antibiotic treatment
or prescription.
STATISTICAL METHODS
Continuous variables were described with means, SDs, and 95% confidence
intervals (CIs). Discrete variables were described with counts and percentages,
with binomial exact 95% CIs. Continuous variables were analyzed with the Wilcoxon
2-sample test. Categorical variables were analyzed with the  2
test or Fisher exact test. Relative risks with exact 95% CIs were calculated.
Statistical significance was determined a priori as P<.05.
RESULTS
Blood cultures were obtained in 379 children with febrile seizures examined
and discharged from the ED. The mean age was 15.9 ± 4.7 months (median,
16.0 months; range, 2-24 months). Most patients were older than 12 months
(76.0%), and only 8 (2.1%) were younger than 6 months. The majority of patients
were male (57.3%). The mean temperature was 39.9 ± 0.8°C, and 38
(10.0%) of 379 children had a maximum temperature of less than 39.0°C
recorded in the ED. Forty patients (10.6%) reported the use of oral antibiotics
before initial ED evaluation. Seventy-three percent of the patients were given
an associated discharge diagnosis from the ED. The most common associated
discharge diagnoses from the initial ED visit included acute otitis media
(64.1%), viral syndrome or upper respiratory tract infection (23.2%), and
pneumonia (6.2%) (Table 1).
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Table 1. Associated Diagnoses in Patients 2 to 24 Months Old With Febrile
Seizures
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The prevalence of bacteremia was 2.1% (95% CI, 0.9%-4.1%). Streptococcus pneumoniae was the pathogen in 7 cases and group A Streptococcus in 1 case. Six (85.7%) of 7 cases of S pneumoniae bacteremia were caused by serotypes currently
included in the pneumococcal conjugate vaccine, which was not available at
the time of the study. The rate of contamination was 1.3% (95% CI, 0.4%-3.0%).
Chest radiographs were obtained more frequently in patients who were later
identified to have bacteremia (62.5%) than in those with negative or contaminated
cultures (28.3%), but this difference did not reach statistical significance
(relative risk, 0.97; 95% CI, 0.92-1.01). No patient with bacteremia was diagnosed
as having pneumonia. There were no statistically significant differences in
age, sex, temperature, or receipt of oral antibiotics before ED visit between
patients who were later identified to have bacteremia and those with negative
or contaminated cultures (Table 2).
A complete blood cell count was obtained in 36.1% of patients. There was no
statistically significant difference in white blood cell count between patients
who were later identified to have bacteremia (14.3 x 103
± 5.9 x 103/µL) and those with negative or contaminated
cultures (18.6 x 103 ± 8.9 x 103/µL; P = .32). Although cultures with pathogenic bacteria became
positive in less time (13.4 ± 1.3 hours) than contaminated cultures
(16.5 ± 5.4 hours), this difference did not reach statistical significance
(P = .27).
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Table 2. Characteristics of Patients With Febrile Seizures With and
Without Bacteremia
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All 8 patients with pathogenic bacteria isolated from blood cultures
had documented follow-up in the ED (Table
3). Six of these patients were afebrile and were discharged after
reevaluation. Five of the 6 patients underwent second blood cultures, all
of which were negative. No other studies were performed in those patients.
Patients 1 and 4 were still febrile and were hospitalized after reevaluation.
The white blood cell counts at the time of reevaluation were 13.0 x
103/µL and 30.5 x 103/µL, respectively.
Blood cultures were repeated in both patients and were negative. Patient 4
also underwent lumbar puncture when reexamined, and the results were unremarkable.
None of the patients were diagnosed as having meningitis or had other serious
adverse outcome.
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Table 3. Characteristics of Patients With Febrile Seizures and Bacteremia*
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COMMENT
Occult bacteremia is defined as the presence of pathogenic bacteria
in the blood of a well-appearing febrile child without an identifiable focus
of infection. Previous studies have identified age 2 to 24 months as a risk
factor for occult bacteremia.7-8
In the post–H influenzae type b era, the prevalence
of occult bacteremia in this age group is 1.6% to 2.6%.7-9
The risk of bacteremia in children presenting with febrile seizures has been
less well defined.
McIntyre et al5 noted bacteremia in 4.3%
of children with febrile seizures; however, the majority of those patients
were hospitalized. Outpatient studies of children with febrile seizures report
rates of bacteremia ranging from 2.7% to 6.7%, but these studies include children
up to 7 years of age, a population at low risk of bacteremia.2-4,6
The prevalence of bacteremia in this study, while lower than that reported
in other studies of children with febrile seizures, is similar to recent reports
of the prevalence of occult bacteremia by Alpern et al7
(1.9%; 95% CI, 1.5%-2.3%) and Lee and Harper9
(1.6%; 95% CI, 1.3%-1.8%).
There was no difference in the frequency with which chest radiographs
were obtained; however, 17 patients with negative or contaminated cultures
and no patients with bacteremia were diagnosed as having pneumonia. Variables
found to be associated with occult bacteremia in other studies, such as temperature
and white blood cell count,8-9
were not significantly different between patients with and without bacteremia
in this study. The low rate of bacteremia and, thus, small sample size may
underestimate potential differences between these 2 groups.
Approximately 10% of children in this study received antibiotics before
ED evaluation. If children who received antibiotics before evaluation are
at lower risk of bacteremia, the overall risk of bacteremia may have been
underestimated. In addition, the American Academy of Pediatrics practice parameter
urges clinicians to "strongly consider" a lumbar puncture in the child younger
than 12 months who presents with febrile seizures.1
Since children undergoing lumbar puncture were excluded from this study, these
younger children may be underrepresented in our population. However, the population
presented in this study most accurately represents children who a practitioner
may most worry are at risk for occult bacteremia and, therefore, consider
examining with a blood culture alone.
Since our study was a retrospective evaluation of a cohort of patients
with febrile seizures evaluated by blood culture, we might expect that physicians
would have obtained blood cultures on those children they considered to be
at highest risk for bacteremia. This may have led to a prevalence rate that
overestimated that of all-comers but closely estimates that in clinical practice.
The detection of bacteremia and prevention of serious complications
are important goals in the examination of febrile young children. The data
in this study indicate that children 2 to 24 months of age with febrile seizures
and without clinical indication for lumbar puncture are at similar risk of
occult bacteremia as those with fever alone. Since most cases of bacteremia
in this study were due to S pneumoniae, widespread
use of the pneumococcal conjugate vaccine may decrease the incidence of occult
bacteremia in this population even further.
| What This Study Adds
In the post–H influenzae type b era,
the prevalence of occult bacteremia in febrile children aged 2 to 24 months
is 1.6% to 2.6%. The risk of bacteremia in children presenting with febrile
seizures is less well defined.
The data in this study suggest that well-appearing children 2 to 24
months of age with febrile seizures are at similar risk for occult bacteremia
as those with fever alone. Furthermore, the majority of cases of bacteremia
in this study were due to S pneumoniae, and there
were no serious adverse outcomes. The widespread use of the pneumococcal conjugate
vaccine may decrease the rate of bacteremia even further.
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AUTHOR INFORMATION
Accepted for publication January 11, 2002.
Corresponding author and reprints: Samir S. Shah, MD, Division of
General Pediatrics, The Children's Hospital of Philadelphia, 34th Street and
Civic Center Boulevard, Philadelphia, PA 19104 (e-mail: shahs{at}email.chop.edu).
From the Divisions of General Pediatrics (Drs Shah, Zwerling, Reid,
and Bell), Immunologic and Infectious Diseases (Drs Shah, McGowan, and Bell),
and Emergency Medicine (Drs Alpern and Bell), The Children's Hospital of Philadelphia,
Philadelphia, Pa. Dr Zwerling is now with the Department of Emergency Medicine,
Children's Hospital of Los Angeles, Los Angeles, Calif; Dr Reid is now with
the Division of Emergency Medicine, Children's Hospital and Regional Medical
Center, Seattle, Wash.
REFERENCES
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1. Provisional Committee on Quality Improvement, Subcommittee on Febrile
Seizures. Practice parameter: the neurodiagnostic evaluation of the child with
a first simple febrile seizure. Pediatrics. 1996;97:769-772.
FREE FULL TEXT
2. Lewin GA, Nakasato C, Overturf GD, Wingert W. Bacteremia in outpatients [abstract]. Clin Res. 1976;24:176A.
3. Lewis HM, Parry JV, Parry RP, et al. Role of viruses in febrile convulsions. Arch Dis Child. 1979;54:869-876.
FREE FULL TEXT
4. Chamberlain JM, Gorman RL. Occult bacteremia in children with simple febrile seizures. AJDC. 1988;142:1073-1076.
5. McIntyre PB, Gray SV, Vance JC. Unsuspected bacterial infections in febrile convulsions. Med J Aust. 1990;152:183-186.
ISI
| PUBMED
6. Teach SJ, Geil PA. Incidence of bacteremia, urinary tract infections, and unsuspected
bacterial meningitis in children with febrile seizures. Pediatr Emerg Care. 1999;15:9-12.
ISI
| PUBMED
7. Alpern ER, Alessandrini EA, Bell LM, Shaw KN, McGowan KL. Occult bacteremia from a pediatric emergency department: current prevalence,
time to detection, and outcome. Pediatrics. 2000;106:505-511.
FREE FULL TEXT
8. Kuppermann N, Fleisher GR, Jaffe DM. Predictors of occult pneumococcal bacteremia in young febrile children. Ann Emerg Med. 1998;31:679-687.
FULL TEXT
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ISI
| PUBMED
9. Lee GM, Harper MB. Risk of bacteremia for febrile young children in the post-Haemophilus influenzae type b era. Arch Pediatr Adolesc Med. 1998;152:624-628.
FREE FULL TEXT
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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
Risk of Bacteremia in Young Children With Pneumonia Treated as Outpatients
Shah et al.
Arch Pediatr Adolesc Med 2003;157:389-392.
ABSTRACT
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Seizures Don't Increase Risk for Bacteremia in Febrile Young Children
JWatch General 2002;2002:5-5.
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