Reevaluation of outpatients with Streptococcus pneumoniae bacteremia

High Rate of Febrile Seizures in Japanese Children With Occult Bacteremia

OBJECTIVES

Fever of 39°C or higher and a white blood cell (WBC) count of 15,000/μL or greater are known predictors of occult bacteremia (OB). However, because of a decreasing prevalence of OB, WBC counts have become poor predictors of OB in populations of routinely immunized children. Thus, we aim to evaluate the clinical characteristics of OB in Japanese children and identify potential risk factors for OB.

METHODS

We conducted an observational study of children aged 3 to 36 months old with positive blood cultures for Streptococcus pneumoniae or Haemophilus influenzae at an emergency department in a tertiary care children's hospital between April 2002 and December 2015. Patients with significant underlying diseases, a proven source of infection, or toxic appearance, were excluded.

RESULTS

Positive blood cultures were recorded in 231 patients; of these, 110 were included in the study (S. pneumoniae, n = 102; H. influenzae, n = 8). Median age was 16 (3-34) months. Patients had a high median body temperature of 39.2 (interquartile range, 38.6-39.9) °C and median WBC of 21,120 (interquartile range, 16,408-24,242)/μL. A high rate of febrile seizures (58 patients, 53%) was observed, with complex febrile seizures accounting for 43% of the episodes. Frequency of febrile seizures was positively associated with age (P = 0.001).

CONCLUSIONS

Our study revealed a high rate of children presenting with febrile seizures, especially complex seizures, among children with OB in Japan. A further study is necessary to evaluate the role of febrile seizures as a predictor for OB.

Occult bacteremia etiology following the introduction of 13-valent pneumococcal conjugate vaccine: a multicenter study in Spain

Little is known about occult bacteremia (OB) in Spain following the introduction of the 13-valent pneumococcal conjugated vaccine (PCV13). Our aim was to describe the microbiologic characteristics and management of OB among children aged 3-36 months in Spain in the era of PCV13. Data were obtained from a multicenter registry of positive blood cultures collected at 22 Spanish emergency departments (ED). Positive blood cultures performed on patients aged 3-36 months from 2011 to 2015 were retrospectively identified. Immunocompetent infants with a final diagnosis of OB were included. Non-well-appearing patients and patients with fever > 72 h were excluded. We analyzed 67 cases (median age 12.5 months [IQR 8.7-19.4]). Thirty-seven (54.4%) had received ≥ 1 dose of PCV. Overall, 47 (70.1%) were initially managed as outpatients (38.3% of them with antibiotic treatment). Phone contact was established with 43 (91.5%) of them after receiving the blood culture result and 11 (23.4%) were hospitalized with parenteral antibiotic. All patients did well. Streptococcus pneumoniae was isolated in 79.1% of the patients (42.2% of the isolated serotypes were included in the PCV13). S. pneumoniae remains the first cause of OB in patients attended in the ED, mainly with non-PCV13 serotypes. Most of the patients with OB were initially managed as outpatients with no adverse outcome.

Antibiotic duration and timing of the switch from intravenous to oral route for bacterial infections in children: systematic review and guidelines

Few studies are available to inform duration of intravenous antibiotics for children and when it is safe and appropriate to switch to oral antibiotics. We have systematically reviewed antibiotic duration and timing of intravenous to oral switch for 36 paediatric infectious diseases and developed evidence-graded recommendations on the basis of the review, guidelines, and expert consensus. We searched databases and obtained information from references identified and relevant guidelines. All eligible studies were assessed for quality. 4090 articles were identified and 170 studies were included. Evidence relating antibiotic duration to outcomes in children for some infections was supported by meta-analyses or randomised controlled trials; in other infections data were from retrospective series only. Criteria for intravenous to oral switch commonly included defervescence and clinical improvement with or without improvement in laboratory markers. Evidence suggests that intravenous to oral switch can occur earlier than previously recommended for some infections. We have synthesised recommendations for antibiotic duration and intravenous to oral switch to support clinical decision making and prospective research.

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.

[Blood cultures in the paediatric emergency department. Guidelines and recommendations on their indications, collection, processing and interpretation]

Blood culture (BC) is the gold standard when a bacteraemia is suspected, and is one of the most requested microbiological tests in paediatrics. Some changes have occurred in recent years: the introduction of new vaccines, the increasing number of patients with central vascular catheters, as well as the introduction of continuous monitoring BC systems. These changes have led to the review and update of different factors related to this technique in order to optimise its use. A practice guideline is presented with recommendations on BC, established by the Spanish Society of Paediatric Emergency Care and the Spanish Society for Paediatric Infectious Diseases. After reviewing the available scientific evidence, several recommendations for each of the following aspects are presented: BC indications in the Emergency Department, how to obtain, transport and process cultures, special situations (indications and interpretation of results in immunosuppressed patients and/or central vascular catheter carriers, indications for anaerobic BC), differentiation between bacteraemia and contamination when a BC shows bacterial growth and actions to take with a positive BC in patients with fever of unknown origin.

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

CONTEXT

Fever without source (FWS) in children 3-36 months is a common presenting complaint. Because of changes in immunization practices and their effects on rates of bacteremia, older guidelines may no longer be applicable. We reviewed the literature regarding the necessity of obtaining a blood culture in non-toxic children in this age group with FWS.

DATA SOURCES

We conducted a MEDLINE search on the topic of bacteremia in febrile children 3-36 months from 2004-present.

RESULTS

Eight studies were included. Although the studies varied in terms of approach and analysis, all suggested a rate of bacteremia in a non-toxic, febrile child 3-36 months of age to be less than 1%.

CONCLUSIONS

Strong consideration should be given for foregoing blood culture in a non-toxic child 3-36 months of age with FWS.

Occult pneumococcal bacteremia: a review

Occult bacteremia is primarily caused by Streptococcus pneumoniae and has been an intense clinical controversy in pediatric emergency medicine, with passionate opinions rendered from inside and outside the field. Vaccine development and widespread immunization have rapidly affected the changing epidemiology of this disease. There is a growing consensus that the reduction in incidence of occult bacteremia and the significant problem of antibiotic resistance are tipping the balance in favor of no testing and no treatment for well-appearing febrile children between 6 and 36 months of age who are immunized with Haemophilus influenzae B vaccination and PCV-7 (pneumococcal conjugate vaccine). This review of occult pneumococcal bacteremia will not only elaborate on current knowledge and clinical practice, but will also provide historical context to this fascinating phenomenon.

The evolving approach to the young child who has fever and no obvious source

Fever is a common complaint of young children who seek care in the emergency department. Recent advances, such as universal vaccination with the pneumococcal conjugate vaccine, require the review of traditional approaches to these patients. This article discusses newer strategies in the evaluation and management of the young child with fever, incorporating changes based on the shifting epidemiology of bacterial infection.

Factors associated with antimicrobial resistance and mortality in pneumococcal bacteremia

We conducted a multicenter, retrospective cohort study of patients with Streptococcus pneumoniae bacteremia to determine factors associated with antibiotic resistance and mortality. Risk factors were identified using multivariate logistic regression. There were 1574 patients at 34 sites enrolled. Compared to isolates from patients not receiving an antibiotic before the index blood culture, patients receiving an antibiotic were less likely to harbor an antibiotic susceptible organism. Susceptibility to penicillin decreased from 78% (95% confidence interval [CI] 75-80) to 49% (95% CI 39-59); to cefotaxime/ceftriaxone, from 92% (95% CI 90-93) to 82% (95% CI 72-89); and to macrolide, from 84% (95% CI 82-87) to 55% (95% CI 41-68). Factors associated with macrolide non-susceptibility include: > 24 h of antibiotic therapy at time of the index culture (odds ratio [OR] 4.0), residing in southern U.S. (OR 1.7), and having an antibiotic allergy (OR 1.7). Harboring an antibiotic non-susceptible strain (OR 1.4) and male sex (OR 1.4) were associated with increased risk of mortality, whereas black race (OR 0.6) and evidence of focal infection (OR 0.6) were associated with decreased risk.

An analysis of pediatric blood cultures in the postpneumococcal conjugate vaccine era in a community hospital emergency department

OBJECTIVE

Blood cultures are commonly included in the evaluation of febrile children younger than 3 years without focal source of infection. Clinicians treat patients with a positive blood culture before final identification of the organism. Their treatment might include reevaluation in the emergency department (ED), additional tests, parenteral antibiotics, and hospital admission even for children who ultimately have false-positive (FP) blood cultures. The advent of pneumococcal conjugate vaccine (PCV) has made occult bacteremia less common, decreasing the likelihood that a positive blood culture result before final organism identification will be a true pathogen. This study will identify the characteristics of patients with FP blood cultures in the post-PCV era.

METHODS

Charts were reviewed of all children ages 1 to 36 months with a temperature of at least 38.08 degrees C who had a blood culture obtained in our community hospital ED from January 1997 to January 2005.

RESULTS

Bacteria grew in 106 (3.5%) out of 2971 blood cultures. True positives (TPs), defined as true pathogens, had a prevalence of 0.7%, representing 19.8% of positives. FPs, defined as contaminants, occurred in 2.8% of cultures, representing 80.2% of positives. Patients with FP cultures had lower mean white blood cell (WBC) counts (10.51 x 10(9)/L vs. 16.95 x 10(9)/L; P = 0.0001) and lower mean presenting temperatures (38.8 degrees C vs. 39.4 degrees C; P = 0.005). FPs had longer time to positivity (34.6 vs. 17.7 hours; P = 0.001) than TPs. A culture with a Gram stain suggestive of a contaminant, time to positivity greater than 24 hours and a WBC of less than 15 x 10(9)/L had a PPV for an FP of 97%. When analysis was restricted to well-appearing children age 2 to 36 months with temperature of more than 39 degrees C without focal source of infection who were discharged from the ED, these three criteria had a PPV for an FP of 100%. In these highly febrile children, the FPs had significantly lower WBCs (9.14 x 10(9)/L vs. 22.84 x 10(9)/L; P = 0.0001) and longer time topositivity (33.4 vs. 19.8 hours; P = 0.007) than TPs. The likelihood of obtaining FP cultures increased after the introduction of PCV from 62.5% to 87.8% odds ratio, 4.3; 95%confidence internal, 1.44-13.38).

CONCLUSIONS

In the post-PCV era, the majority of blood culture results will be FPs. FP cultures are predictable in febrile children with WBC counts less than 15.00 x 10(9)/L, time to positivity of more than 24 hours, and a Gram stain result suggestive of a contaminant. Prospective studies applying these criteria to the at-risk population for occult bacteremia are indicated.

Changing epidemiology of outpatient bacteremia in 3- to 36-month-old children after the introduction of the heptavalent-conjugated pneumococcal vaccine

BACKGROUND

The introduction of routine vaccination with heptavalent conjugated pneumococcal vaccine has changed the overall incidence of bacteremia in children 3 months-3 years old.

OBJECTIVE

To describe the changing incidence and etiology of bacteremia in previously healthy toddlers presenting to outpatient clinical settings.

METHODS

Retrospective case series of all blood cultures obtained between September 1998 and August 2003 in Kaiser Permanente Northern California outpatient clinics and emergency departments from previously healthy children 3 months-3 years old.

RESULTS

Implementation of routine vaccination with the conjugated pneumococcal vaccine resulted in an 84% reduction of Streptococcus pneumoniae bacteremia (1.3-0.2%) and a 67% reduction in overall bacteremia (1.6-0.7%) in the study population. The rate of blood culture isolation of contaminating organisms remained unchanged at 1.8%; therefore, by the end of the study, >70% of organisms identified in blood cultures were contaminants. During the 5 study years, total blood cultures drawn decreased by 35% in outpatient pediatric clinics but remained unchanged in emergency departments. By 2003, one-third of all pathogenic organisms isolated from blood cultures were Escherichia coli, one-third were non-vaccine serotype S. pneumoniae, the majority of the remaining one-third were Staphylococcus aureus, Salmonella spp., Neisseria meningitidis and Streptococcus pyogenes. In our population of children routinely immunized with the conjugated pneumococcal vaccine, a white blood cell count >15,000 by itself is a poor predictor of bacteremia in the febrile toddler (sensitivity, 74.0%; specificity, 54.5%; positive predictive value, 1.5%; negative predictive value, 99.5%).

CONCLUSION

In the United States, routine vaccinations with Haemophilus influenzae type b and S. pneumoniae vaccines have made bacteremia in the previously healthy toddler a rare event. As the incidence of pneumococcal bacteremia has decreased, E. coli, Salmonella spp. and Staphylococcus aureus have increased in relative importance. The use of the white blood cell count alone to guide the empiric use of antibiotics is not indicated. New guidelines are needed to approach the previously healthy febrile toddler in the outpatient setting.

Fever without source in children 0 to 36 months of age

Although fever in the young child (0-36 months) is a common clinical problem, the evaluation and treatment of febrile children remain controversial. Furthermore, universal vaccination with the heptavalent pneumococcal conjugate vaccine (PCV7) has changed the epidemiology of invasive bacterial disease in young children. This article addresses the approach to febrile neonates (0-28 days old), young infants (1-3 months old), and older infants and toddlers (3-36 months old) in the PCV7 era.

Unexplained fever in young children: how to manage severe bacterial infection

Fever with no clear source of infection in children under 3 years old carries a small but important risk of sepsis and meningitis. This review describes the bacterial causes of such infection and the appropriate management in different age groups

Fever in children less than 36 months of age--questions and strategies for management in the emergency department

Fever is a common pediatric complaint in the Emergency Department. Emergency Physicians often must be conservative in their management of febrile children, as patient follow-up is not always available. A unified approach for the management of febrile infants will be discussed in this article.

Clinical aspects and cost of invasive Streptococcus pneumoniae infections in children: resistant vs. susceptible strains

Invasive Streptococcus pneumoniae infections in children are associated with serious consequences in terms of morbidity and mortality. The main objective of the study was to determine if invasive infections caused by penicillin-resistant Streptococcus pneumoniae (PRSP) differed in clinical presentation, outcome, risk factors, or cost from those caused by penicillin-susceptible strains (PSSP) in children. All patients aged 18 or less with invasive Streptococcus pneumoniae infections admitted to two teaching hospitals in Montreal between 1989 and 1998 were included in the study. We present a case-control study in which for each index case of PRSP, 3 controls with PSSP infections were matched for age, sex, and site of infection. One hundred and forty-four patients were included in the analysis (36 cases, 108 controls). There was no difference between the two groups in terms of initial clinical presentation (vital signs, laboratory results) or total length of stay. Mortality was 2.7% in both groups. Hospital antibiotic cost was higher in the PRSP group (211 Canadian dollars (CAD) vs. 74 CAD; P=0.02). Antibiotic consumption in the preceding month was significantly associated with PRSP infection. Underlying diseases or day-care attendance were not shown to be significant risk factors for acquiring invasive PRSP infection. There were no differences between invasive infections caused by PRSP and PSSP in terms of clinical presentation, morbidity or mortality in a paediatric population.

Revising the decision analysis for febrile children at risk for occult bacteremia in a future era of widespread pneumococcal immunization

Previous decision analyses (DA), which have attempted to determine a superior management option for febrile children at risk for occult bacteremia, have come to different conclusions based on their underlying assumptions. Most DAs have recommended a laboratory evaluation with antibiotic treatment or have concluded that all management options are roughly the same. The purpose of this revised DA is to determine which management strategy will be superior in an anticipated era of widespread pneumococcal immunization. Decision analysis methodology comparing the following 3 management options: Obs: observation, no tests, no antibiotics; CBC+: Complete blood count (CBC) first; if the white blood cell count (WBC) >15,000, then blood culture (BC) plus antibiotics (Abx); BC+Abx: BC+Abx for all patients. Assumptions include a current bacteremia rate of 2% to 4%, and 95% of this bacteremia is caused by S. pneumococcus (which has a 15% persistent bacteremia rate) with the remainder caused by virulent bacteria (which has a 100% persistent bacteremia rate), and other assumptions made by previous decision analysis publications. Pneumococcal vaccine efficacy rates of 0%, 50%, 75%, and 100% in preventing pneumococcal bacteremia were analyzed. Overall death and neurologic sequelae rates are lower with efficacious pneumococcal vaccine. The Obs strategy is superior for all efficacy rates (including 0%) if the negative consequences of treatment are high. If the negative consequences of treatment are low, the CBC+ strategy is superior at pneumococcal vaccine efficacy rates of 50% or greater. The absolute differences between the outcomes of the 3 strategies are small, making them similar. This decision analysis indicates that widespread efficacious pneumococcal vaccine will reduce the overall morbidity and mortality associated with pneumococcal bacteremia. This favors the Obs strategy, but the superior management strategy is still dependent on an assumption of the negative consequences of treatment. Since the outcome measures for each of the management strategies are similar numerically, the strategy chosen in clinical practice may consider other factors associated with the clinical encounter such as those described.

Sequential antibiotic therapy

Antimicrobials are an important source of hospital expenditure. Traditionally, severe bacterial infections have been treated initially with intravenous antibiotics, followed by physician-directed switch to oral therapy. Unfortunately this approach results in unnecessary prolongation of intravenous treatment, with all its inherent disadvantages. Sequential antibiotic therapy, however, ensures an early switch to the oral route when the patient is clinically stable. This increasingly employed strategy is safe and results in improved quality and cost-effectiveness of health care. To ensure timely and appropriate switch, such programmes need to be underpinned by clear guidelines and supported by a multidisciplinary team. In the future, key questions, such as what is the optimal time of switch for specific infections, and can conditions such as osteomyelitis and endocarditis be efficaciously treated with oral therapy, need to be answered. Only then will clinicians be able to practise evidence-based infection management incorporating sequential antimicrobial therapy.