ARTICLE Risk of Bacteremia in Young Children With Pneumonia Treated as Outpatients Samir S. Shah, MD; Elizabeth R. Alpern, MD; Lisa Zwerling, MD, MPH; Karin L. McGowan, PhD; Louis M. Bell, MD Background: Blood cultures are often obtained as part emia was 1.6% (95% confidence interval, 0.7%-2.9%). of the evaluation of children with pneumonia. There are Streptococcus pneumoniae was the causative organism in few data regarding the risk of bacteremia with pneumo- all 9 cases. The serotype was available for 8 of 9 cases. nia in children since introduction of the Haemophilus in- Six (75%) of 8 cases of S pneumoniae bacteremia were fluenzae type b vaccine. caused by serotypes included in the current heptavalent pneumococcal conjugate vaccine, which was not avail- Objective: To evaluate the risk of bacteremia in young able at the time of this study. The contamination rate was children with pneumonia who were treated as outpa- 1.9% (95% confidence interval, 1.0%-3.4%). The tients. mean±SD time to blood culture positive for organisms in a continuously monitored system was significantly Methods: A retrospective cohort study of 580 children shorter for pathogens (13.9±1.3 hours) than for con- aged 2 to 24 months who were evaluated by blood cul- taminants (21.2±6.1 hours; P=.01). ture in a tertiary care children’s hospital emergency de- partment between February 1, 1993, and May 31, 1996, Conclusions: Children aged 2 to 24 months with pneu- and discharged with the diagnosis of pneumonia. monia who are treated as outpatients are at low risk of bacteremia. Widespread use of the pneumococcal con- Results: The mean patient age was 14.1 months; 339 jugate vaccine may further decrease the incidence of bac- patients (58.4%) were boys. Thirty-eight patients (6.6%) teremia in this population. reported the use of oral antibiotics before initial emer- gency department evaluation. The prevalence of bacter- Arch Pediatr Adolesc Med. 2003;157:389-392 LOOD CULTURES are often ob- children with pneumonia who were to be tained as part of the outpa- treated in the outpatient setting.6 tient evaluation of children Since introduction of the H influen- with pneumonia. The risk of zae type b vaccine, few data have become bacteremia with pneumo- available regarding the risk of bacteremia Bnia in this population is unclear. In the with pneumonia in children. We per- pre–Haemophilus influenzae type b vac- formed a retrospective cohort study to de- cine era, Bonadio1 noted that bacteremia termine the occurrence of bacteremia in was present in 1 (1%) of 86 children with young children with pneumonia who were pneumonia. Only 2 (1.8%) of 109 chil- treated as outpatients. dren evaluated by Ramsey et al2 had bac- 3-5 teremia. Meanwhile, other researchers METHODS found rates of bacteremia ranging from From the Divisions of General 7.7% to 9.6% in children with pneumo- STUDY DESIGN AND SETTING Pediatrics (Drs Shah, Zwerling, nia; H influenzae and Streptococcus pneu- and Bell), Infectious Diseases moniae were the most common bacterial This retrospective cohort study included chil- (Drs Shah, McGowan, and pathogens identified. These previous stud- dren aged 2 to 24 months with pneumonia who Bell), and Emergency Medicine ies included children treated as outpa- had blood cultures drawn in an urban tertiary (Drs Alpern and Bell), The tients and those requiring hospitaliza- care children’s hospital emergency depart- Children’s Hospital of ment (ED) (The Children’s Hospital of Phila- Philadelphia, Philadelphia, Pa. tion. They also included children of a wide delphia) between February 1, 1993, and May Dr Zwerling is now with the age distribution. Given the potentially high 31, 1996. A subset of this cohort of children Department of Emergency risk of bacteremia, even in children who with pneumonia is included in a previously de- Medicine, Children’s Hospital of did not require hospitalization, experts rec- scribed population of children with febrile sei- Los Angeles, Los Angeles, Calif. ommended obtaining blood cultures on zures.7 At the time of the study, the ED cared (REPRINTED) ARCH PEDIATR ADOLESC MED/ VOL 157, APR 2003 WWW.ARCHPEDIATRICS.COM 389 ©2003 American Medical Association. All rights reserved. Downloaded From: http://archpedi.jamanetwork.com/ by a University of Chicago Libraries User on 05/29/2013 for approximately 54000 children annually. The institutional tococci, Micrococcus species, Clostridium species, Corynebac- review board of The Children’s Hospital of Philadelphia approved terium species, and Neisseria species other than N meningitidis the study. or Neisseria gonorrhoeae. Time to positive culture was mea- Standard practice during the study was to obtain blood cul- sured and recorded in hours and tenths of hours. tures from children 2 to 24 months of age who had tempera- tures of 39.0°C or higher, but it did not include routine com- STATISTICAL METHODS plete blood cell counts. The decision to obtain blood cultures on children 2 to 24 months of age with pneumonia and tem- Continuous variables are described using mean±SD and 95% peratures less than 39.0°C was made at the discretion of the confidence intervals (CIs). Discrete variables are described us- attending physician. During a subset of the study that ac- ing counts and percentages, with binomial exact 95% CIs. Con- counts for one third of the enrollment time, 82% of children tinuous variables were analyzed using the Wilcoxon 2-sample with temperatures of 39.0°C or higher were documented to have test. Categorical variables were analyzed using the ␹2 test or blood cultures obtained.8 Blood cultures were obtained by ED Fisher exact test. Relative risks with exact 95% CIs were cal- nurses using sterile techniques and were inoculated into pedi- culated. Statistical significance was determined a priori as PϽ.05. atric blood culture bottles (Pedi-Bac T; bioMe´rieux, Durham, NC). A single bottle containing supplemented brain heart in- RESULTS fusion broth with 0.02% sodium polyanethol sulfonate was in- oculated for each blood culture ordered. Standard procedure in the ED was to inoculate 0.5 to 1.0 mL. Through a pneu- Blood cultures were obtained in 667 children diagnosed matic tube delivery system, blood cultures were routinely re- as having pneumonia and discharged from the ED after ceived in the laboratory within an hour of when they were ob- evaluation. A chest radiograph was not performed in 76 tained and were immediately loaded into the blood culture children (11.4%), and these children were excluded from instrument. The microbiology laboratory used a microbial de- further analysis. None of the 76 children excluded from tection system (BacT/Alert; bioMe´rieux) to process all blood further study had bacteremia. Eleven (1.6%) of the 667 cultures. The BacT/Alert system monitored carbon dioxide pro- children had underlying conditions, including congen- duction within each bottle every 10 minutes, 24 hours per day. ital heart disease (n=4), static encephalopathy (n=3), hy- Bottles identified as positive were immediately removed from drocephalus with ventriculoperitoneal shunt (n=2), cys- the instrument, 24 hours per day, and an aliquot was taken for tic fibrosis (n=1), and tuberculosis (n=1), and were also gram stain and subculture. The ED was notified immediately excluded from further analysis. Of the remaining 580 chil- of the positive culture result and was given information from the gram stain. Bacterial isolates were identified by conven- dren, 339 (58.4%) were boys. The mean patient age was tional procedures. Only information from the gram stain, how- 14.1±5.1 months (median, 14.0 months; range, 2-24 ever, was available at the time of the initial report of positive months). Most children were 6 months or older (96.9%). culture results to the ED. Routine protocol included contact- The mean temperature was 39.9°C±0.8°C, and 524 pa- ing families of all children with positive blood culture find- tients (90.3%) had a temperature of 39.0°C or higher at ings for reevaluation. initial evaluation. Thirty-eight patients (6.6%) reported the use of oral antibiotics before initial ED evaluation. PARTICIPANTS Concurrent acute otitis media was diagnosed during the initial ED visit in 169 children with pneumonia (29.1%). Potential study participants were identified using microbiol- After being diagnosed as having pneumonia, 571 (98.4%) ogy laboratory data from the BacT/Alert system. Patients 2 to 24 months of age were included if they were diagnosed as hav- of the 580 children were documented to have been pre- ing pneumonia confirmed by chest radiography, had a blood scribed antibiotics. culture obtained during the initial ED evaluation, and were dis- The prevalence of bacteremia was 1.6% (95% CI, charged after evaluation. The diagnosis of pneumonia was de- 0.7%-2.9%); S pneumoniae was the causative organism in termined by documentation of attending pediatric emergency all 9 cases. The serotype was available for 8 of 9 cases medicine physician evaluation of the chest radiograph on the (Table). Six (75%) of 8 cases of S pneumoniae bacter- ED chart or by attending pediatric radiologist report of infil- emia were caused by serotypes included in the current trate on the chest radiograph. Patients were excluded if dur- heptavalent pneumococcal conjugate vaccine, which was ing initial ED evaluation they (1) were known to have an un- not available at the time of this study. All S pneumoniae derlying condition that predisposed them to bacteremia (eg, isolates were sensitive to penicillin exposure. The rate sickle cell anemia, oncologic disease, immunodeficiency, or in- dwelling central catheter), (2) underwent lumbar puncture (used of contamination was 1.9% (95% CI, 1.0%-3.4%). Cul- as a proxy for clinical suspicion of meningitis, sepsis, or clini- tures with pathogenic bacteria became positive in less time cally evident bacteremia), or (3) had an illness requiring hos- (13.9±1.3 hours) than contaminated cultures (21.2±6.1 pitalization.