Should blood cultures be obtained in all infants 3 to 36 months presenting with significant fever?

Validation of the Hospital for Sick Children Algorithm for Discriminating Bacteremia From Contaminants in Children With a Preliminary Positive Blood Culture

STUDY OBJECTIVE

Children with positive blood cultures obtained in the emergency department (ED) prompt urgent actions due to the risk of bacteremia. This study aimed to validate the Hospital for Sick Children algorithm used for discriminating bacteremia from contaminants and identified variables associated with bacteremia in children with positive blood cultures.

METHODS

We conducted a retrospective cohort study of all children with positive blood cultures from a tertiary care, pediatric ED between 2018 and 2022. A 2-step standardized approach defined true bacteremia as the primary outcome based on 1) the bacteria involved and 2) the clinical outcome assessed by 2 reviewers. We evaluated multiple independent variables. We used multiple logistic regression to analyze the association between independent variables and outcome.

RESULTS

Among the 375,428 ED visits, 574 participants were identified, including 286 (49.8%; 95% confidence interval [CI] 45.8% to 53.9%) with bacteremia and 288 (50.2%; 95% CI 46.1% to 54.3%) with contaminants. The algorithm identified 364 children (63.4%) at high risk of bacteremia, 178 (31.0%) at medium risk, and 32 (5.6%) at low risk. The corresponding bacteremia proportions were 62%, 34%, and 0%, respectively, for a sensitivity of 100% and a specificity of 11%. Suspicion of osteoarticular infection (aOR=43.6; 95% CI 16.2 to 118), presence of internal hardware (aOR=24.9; 95% CI 7.2 to 83.5), and presence of Gram-negative bacteria or Gram-positive cocci in chains/pairs (aOR=21.7; 95% CI 11.7 to 40.3) were the most significant predictors of true bacteremia.

CONCLUSION

The Hospital for Sick Children algorithm exhibits 100% sensitivity to detect children with bacteremia but demonstrated low specificity at 11%. We identified predictors to discriminate contaminants from bacteremia.

Evaluating the Proportion of Low-Value Blood Cultures Obtained in a Pediatric Emergency Department

BACKGROUND

Existing literature suggests that for some pediatric conditions, blood cultures may be of low value in specific clinical circumstances. The goals of our study were to: 1) identify common pediatric illnesses and define criteria for low-value blood cultures in children aged from 91 days to 19 years, 2) apply these criteria retrospectively to identify the patients in our emergency department (ED) who had low-value blood cultures obtained, and 3) describe this cohort and assess the proportion of true bacteremia in low-value blood cultures.

METHOD

The study team reviewed the literature and developed consensus criteria to identify conditions in which blood cultures were of low value for our study population. The criteria were applied retrospectively to well-appearing patients aged from 91 days to 19 years, without a central venous catheter, and evaluated in our ED with a peripheral blood culture from June 2018 to April 2020. Children admitted to the intensive care/hematology-oncology/cardiology/pulmonary units, those transferred from our ED to an outside facility, who transferred to our ED due to a positive blood culture from an outside facility, and repeat visits of a patient within 30 days from a previous visit were excluded from the study. After chart review, children with fever for 7 days or more, who were unvaccinated, immunosuppressed, had implanted devices, had a complex medical history, or had provider concerns for bacteremia/sepsis were excluded.

RESULTS

The study population consisted of 1436 children. Children at risk for bacteremia (n = 718) were excluded. Four hundred twenty-four children had discharge diagnoses not included in our study. There were 294 (20.5%) patients who had low-value cultures per our study criteria. Nine children (9/294, 3.1%) had false-positive blood cultures, and three (3/294, 1.0%) had true-positive blood cultures.

CONCLUSIONS

We identified a cohort of patients in our ED with blood cultures obtained when available literature indicates they were of low value.

Prevalence of Bacteremia in Febrile Patients With Sickle Cell Disease: Meta-Analysis of Observational Studies

OBJECTIVE

Pneumococcal vaccination has decreased the bacteremia rate in both the general pediatric and sickle cell disease (SCD) populations. Despite this decrease, and an increasing concern for antibiotic resistance, it remains standard practice to obtain blood cultures and administer antibiotics in all febrile (>38.5°C) patients with SCD. We conducted a systematic review and meta-analysis of the available studies of the prevalence of bacteremia in febrile patients with SCD.

METHODS

We searched the medical literature up to November 2018 in PUBMED, EMBASE, and Web of Science with terms epidemiology, prevalence, bacteremia, and sickle cell anemia. We only included studies with patients after 2000, when the pneumococcal 7-valent conjugate (PCV7) vaccine became widely available. The prevalence of bacteremia [95% confidence interval (CI)] was calculated by dividing the number of positive blood cultures by the number of febrile episodes. The I2 statistic measured heterogeneity between prevalence estimates. Bias in our studies was quantified by the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

Our search identified 228 citations with 10 studies meeting our inclusion/exclusion criteria. The weighted prevalence of bacteremia across all studies was 1.9% (95% CI, 1.22%-2.73%), and for Streptococcus pneumoniae bacteremia, it was 0.31% (95% CI, 0.16%-0.50%). Risks for bacteremia except central lines could not be determined because of the low prevalence of the outcome.

CONCLUSIONS

There appears to be a need to develop a risk stratification strategy to guide physicians to manage febrile patients with SCD based on factors including, but not limited to, history and clinical examination, vaccination status, use of prophylactic antibiotics, laboratory values, likely source of infection, and accessibility to health care.

True Versus False Bacteremia in Infants and Children Less Than 3 Years of Age

OBJECTIVE

The objective of this study was to examine patient history as well as clinical and laboratory features associated with true bacteremia versus false bacteremia in previously healthy febrile children ages 0 to 36 months in the era of polyvalent conjugate pneumococcal immunization.

METHODS

Using retrospective chart review, we examined history, physical examination, and laboratory characteristics associated with true and false bacteremia. We included subjects under 3 years old, with a positive blood culture obtained in the emergency department or clinic from July 2011 to July 2013, and fever defined as a temperature of greater than or equal to 100.4°F by history or examination. We excluded those with a previously known underlying disease process that could increase the risk for positive blood culture, for example, immunodeficiency, cancer, cystic fibrosis, or significant skin disorders such as severe eczema, as well as patients with any indwelling central line, shunt, or other implanted device, or recent hospitalization for a febrile illness.

RESULTS

Thirty subjects (24%) had true bacteremia, and 97 (76%) had false bacteremia. In the multivariable logistic regression analysis, exposure to sick contacts (odds ratio, 0.1; 95% confidence interval, 0.01-0.6; P = 0.01) and increased hours to positive blood culture (odds ratio, 0.8; 95% confidence interval, 0.8-0.9; P < 0.001) remained significant factors associated with false bacteremia. Age, maximum reported temperature, and reported days of fever were not associated with true bacteremia.

CONCLUSIONS

We found that previously healthy children with true bacteremia are more likely to grow bacteria faster on blood culture and lack exposure to sick contacts than children with false bacteremia.

Association of Bacteremia with Vaccination Status in Children Aged 2 to 36 Months

OBJECTIVE

To determine the association between bacteremia and vaccination status in children aged 2-36 months presenting to a pediatric emergency department.

STUDY DESIGN

Retrospective cohort study of children aged 2-36 months with blood cultures obtained in the pediatric emergency department between January 2013 and December 2017. The exposure of interest was immunization status, defined as number of Haemophilus influenzae type B (Hib) and Streptococcus pneumoniae vaccinations, and the main outcome positive blood culture. Subjects with high-risk medical conditions were excluded.

RESULTS

Of 5534 encounters, 4742 met inclusion criteria. The incidence of bacteremia was 1.5%. The incidence of contaminated blood culture was 5.0%. The relative risk of bacteremia was 0.79 (95% CI 0.39-1.59) for unvaccinated and 1.20 (95% CI 0.52-2.75) for undervaccinated children relative to those who had received age-appropriate vaccines. Five children were found to have S pneumoniae bacteremia and 1 child had Hib bacteremia; all of these subjects had at least 3 sets of vaccinations. No vaccine preventable pathogens were isolated from blood cultures of unvaccinated children. We found no S pneumoniae or Hib in children 2-6 months of age who were not fully vaccinated due to age (95% CI 0-0.13%) and the contamination rate in this group was high compared with children 7-36 months (6.6% vs 3.7%).

CONCLUSIONS

Bacteremia in young children is an uncommon event. Contaminated blood cultures were more common than pathogens. Bacteremia from S pneumoniae or Hib is uncommon and, in this cohort, was independent of vaccine status.

United States' Emergency Department Visits for Fever by Young Children 2007-2017

Introduction

Our goal in this study was to estimate rates of emergency department (ED) visits for fever by children <2 years of age, and evaluate frequencies of testing and treatment during these visits.

Methods

We performed a cross-sectional study of ED encounters from 2007–2017 using the National Hospital Ambulatory Medical Care Survey, a cross-sectional, multi-stage probability sample survey of visits to nonfederal United States EDs. We included encounters with a visit reason of “fever” or recorded fever in the ED. We report demographics and management strategies in two groups: infants ≤90 days in age; and children 91 days to <2 years old. For patients 91 days to <2 years, we compared testing and treatment strategies between general and pediatric EDs using chi-squared tests.

Results

Of 1.5 billion encounters over 11 years, 2.1% (95% confidence interval [CI], 1.9–2.2%) were by children <2 years old with fever. Two million encounters (95% CI, 1.7–2.4 million) were by infants ≤90 days, and 28.4 million (95% CI, 25.5–31.4 million) were by children 91 days to <2 years. Among infants ≤90 days, 27.6% (95% CI, 21.1–34.1%) had blood and 21.3% (95% CI, 13.6–29.1%) had urine cultures; 26.8% (95% CI, 20.9–32.7%) were given antibiotics, and 21.1% (95% CI, 15.3–26.9%) were admitted or transferred. Among patients 91 days to <2 years in age, 6.8% (95% CI, 5.8–7.8%) had blood and 7.7% (95% CI 6.1–9.4%) had urine cultures; 40.5% (95% CI, 40.5–40.5%) were given antibiotics, and 4.4% (95% CI, 3.5–5.3%) were admitted or transferred. Patients 91 days to <2 years who were evaluated in general EDs had higher rates of radiography (27.1% vs 15.2%; P<0.01) and antibiotic utilization (42.3% vs 34.2%; P<0.01), but lower rates of urine culture testing (6.4% vs 11.6%, p = 0.03), compared with patients evaluated in pediatric EDs.

Conclusion

Approximately 180,000 patients ≤90 days old and 2.6 million patients 91 days to <2 years in age with fever present to US EDs annually. Given existing guidelines, blood and urine culture performance was low for infants ≤90 days old. For children 91 days to <2 years, rates of radiography and antibiotic use were higher in general EDs compared to pediatric EDs. These findings suggest opportunities to improve care among febrile young children in the ED.

Current management of occult bacteremia in infants

OBJECTIVES

To summarize the main clinical entities associated with fever without source (FWS) in infants, as well as the clinical management of children with occult bacteremia, emphasizing laboratory tests and empirical antibiotics.

SOURCES

A non-systematic review was conducted in the following databases--PubMed, EMBASE, and SciELO, between 2006 and 2015.

SUMMARY OF THE FINDINGS

The prevalence of occult bacteremia has been decreasing dramatically in the past few years, due to conjugated vaccination against Streptococcus pneumoniae and Neisseria meningitidis. Additionally, fewer requests for complete blood count and blood cultures have been made for children older than 3 months presenting with FWS. Urinary tract infection is the most prevalent bacterial infection in children with FWS. Some known algorithms, such as Boston and Rochester, can guide the initial risk stratification for occult bacteremia in febrile infants younger than 3 months.

CONCLUSIONS

There is no single algorithm to estimate the risk of occult bacteremia in febrile infants, but pediatricians should strongly consider outpatient management in fully vaccinated infants older than 3 months with FWS and good general status. Updated data about the incidence of occult bacteremia in this environment after conjugated vaccination are needed.